WHEN the sexes differ in beauty
or in the power of singing, or
in producing what I have called
instrumental music, it is almost
invariably the male who surpasses
the female. These qualities,
as we have just seen, are evidently
of high importance to the male.
When they are gained for only
a part of the year it is always
before the breeding-season. It
is the male alone who elaborately
displays his varied attractions,
and often performs strange antics
on the ground or in the air,
in the presence of the female.
Each male drives away, or if
he can, kills his rivals. Hence
we may conclude that it is the
object of the male to induce
the female to pair with him,
and for this purpose he tries
to excite or charm her in various
ways; and this is the opinion
of all those who have carefully
studied the habits of living
birds. But there remains a question
which has an all important bearing
on sexual selection, namely,
does every male of the same species
excite and attract the female
equally? Or does she exert a
choice, and prefer certain males?
This latter question can be answered
in the affirmative by much direct
and indirect evidence. It is
far more difficult to decide
what qualities determine the
choice of the females; but here
again we have some direct and
indirect evidence that it is
to a large extent the external
attractions of the male; though
no doubt his vigour, courage,
and other mental qualities come
into play. We will begin with
the indirect evidence.
Length of Courtship.-
The lengthened period during
which both sexes
of certain birds meet day after
day at an appointed place probably
depends partly on the courtship
being a prolonged affair, and
partly on reiteration in the
act of pairing. Thus in Germany
and Scandinavia the balzen or
leks of the black-cocks last
from the middle of March, all
through April into May. As many
as forty or fifty, or even more
birds congregate at the leks;
and the same place is often frequented
during successive years. The
lek of the capercailzie lasts
from the end of March to the
middle or even end of May. In
North America "the partridge
dances" of the Tetrao phasianellus "last
for a month or more." Other kinds
of grouse, both in North America
and Eastern Siberia,* follow
nearly the same habits. The fowlers
discover the hillocks where the
ruffs congregate by the grass
being trampled bare, and this
shews that the same spot is long
frequented. The Indians of Guiana
are well acquainted with the
cleared arenas, where they expect
to find the beautiful cocks of
the rock; and the natives of
New Guinea know the trees where
from ten to twenty male birds
of paradise in full plumage congregate.
In this latter case it is not
expressly stated that the females
meet on the same trees, but the
hunters, if not specially asked,
would probably not mention their
presence, as their skins are
valueless. Small parties of an
African weaver (Ploceus) congregate,
during the breeding-season, and
perform for hours their graceful
evolutions. Large numbers of
the solitary snipe (Scolopax
major) assemble during dusk in
a morass; and the same place
is frequented for the same purpose
during successive years; here
they may be seen running about "like
so many rats," puffing out their
feathers, flapping their wings,
and uttering the strangest cries.*(2)
* Nordman describes (Bull. Soc.
Imp. des Nat. Moscou, 1861, tom.
xxxiv., p. 264) the balzen of
Tetrao urogalloides in Amur Land.
He estimated the number of birds
assembled at above a hundred,
not counting the females, which
lie hid in the surrounding bushes.
The noises uttered differ from
those of T. urogallus.
*(2) With respect to the assemblages
of the above-named grouse, see
Brehm, Thierleben, B. iv., s.
350; also L. Lloyd, Game Birds
of Sweden, 1867, pp. 19, 78.
Richardson, Fauna Bor. Americana:
Birds, p. 362. References in
regard to the assemblages of
other birds have already been
given. On Paradisea, see Wallace,
in Annals and Mag. of Nat. Hist.,
vol. xx., 1857, p. 412. On the
snipe, Lloyd, ibid., p. 221.
Some of the
above birds,- the black-cock,
capercailzie, pheasant-grouse,
ruff, solitary snipe, and perhaps
others,- are, as is believed,
polygamists. With such birds
it might have been thought that
the stronger males would simply
have driven away the weaker,
and then at once have taken possession
of as many females as possible;
but if it be indispensable for
the male to excite or please
the female, we can understand
the length of the courtship and
the congregation of so many individuals
of both sexes at the same spot.
Certain strictly monogamous species
likewise hold nuptial assemblages;
this seems to be the case in
Scandinavia with one of the ptarmigans,
and their leks last from the
middle of March to the middle
of May. In Australia the lyre-bird
(Menura superba) forms "small
round hillocks," and the M. Alberti
scratches for itself shallow
holes, or, as they are called
by the natives, corroborying
places, where it is believed
both sexes assemble. The meetings
of the M. superba are sometimes
very large; and an account has
lately been published* by a traveller,
who heard in a valley beneath
him, thickly covered with scrub, "a
din which completely astonished" him;
on crawling onwards he beheld,
to his amazement, about one hundred
and fifty of the magnificent
lyre-cocks, "ranged in order
of battle, and fighting with
indescribable fury." The bowers
of the bower-birds are the resort
of both sexes during the breeding-season;
and "here the males meet and
contend with each other for the
favours of the female, and here
the latter assemble and coquet
with the males." With two of
the genera, the same bower is
resorted to during many years.*(2)
* Quoted by Mr. T. W. Wood,
in The Student, April, 1870,
p. 125.
*(2) Gould, Handbook of the
Birds of Australia, vol. i.,
pp. 300, 308, 448, 451. On the
ptarmigan, above alluded to,
see Lloyd, ibid., p. 129.
The common magpie
(Corvus pica, Linn.), as I
have been informed
by the Rev. W. Darwin Fox, used
to assemble from all parts of
Delamere Forest, in order to
celebrate the great magpie marriage." Some
years ago these birds abounded
in extraordinary numbers, so
that a gamekeeper killed in one
morning nineteen males, and another
killed by a single shot seven
birds at roost together. They
then had the habit of assembling
very early in the spring at particular
spots, where they could be seen
in flocks, chattering, sometimes
fighting, bustling and flying
about the trees. The whole affair
was evidently considered by the
birds as one of the highest importance.
Shortly after the meeting they
all separated, and were then
observed by Mr. Fox and others
to be paired for the season.
In any district in which a species
does not exist in large numbers,
great assemblages cannot, of
course, be held, and the same
species may have different habits
in different countries. For instance,
I have heard of only one instance,
from Mr. Wedderburn, of a regular
assemblage of black game in Scotland,
yet these assemblages are so
well known in Germany and Scandinavia
that they have received special
names.
Unpaired Birds.-
From the facts now given, we
may conclude that
the courtship of birds belonging
to widely different groups, is
often a prolonged, delicate,
and troublesome affair. There
is even reason to suspect, improbable
as this will at first appear,
that some males and females of
the same species, inhabiting
the same district, do not always
please each other, and consequently
do not pair. Many accounts have
been published of either the
male or female of a pair having
been shot, and quickly replaced
by another. This has been observed
more frequently with the magpie
than with any other bird, owing
perhaps to its conspicuous appearance
and nest. The illustrious Jenner
states that in Wiltshire one
of a pair was daily shot no less
than seven times successively, "but
all to no purpose, for the remaining
magpie soon found another mate";
and the last pair reared their
young. A new partner is generally
found on the succeeding day;
but Mr. Thompson gives the case
of one being replaced on the
evening of the same day. Even
after the eggs are hatched, if
one of the old birds is destroyed
a mate will often be found; this
occurred after an interval of
two days, in a case recently
observed by one of Sir J. Lubbock's
keepers.* The first and most
obvious conjecture is that male
magpies must be much more numerous
than females; and that in the
above cases, as well as in many
others which could be given,
the males alone had been killed.
This apparently holds good in
some instances, for the gamekeepers
in Delamere Forest assured Mr.
Fox that the magpies and carrion-crows
which they formerly killed in
succession in large numbers near
their nests, were all males;
and they accounted for this fact
by the males being easily killed
whilst bringing food to the sitting
females. Macgillivray, however,
gives, on the authority of an
excellent observer, an instance
of three magpies successively
killed on the same nest, which
were all females; and another
case of six magpies successively
killed whilst sitting on the
same eggs, which renders it probable
that most of them were females;
though, as I hear from Mr. Fox,
the male will sit on the eggs
when the female is killed.
* On magpies, Jenner, in Philosophical
Transactions, 1824, p. 21. Macgillivray,
Hist. British Birds, vol. i.,
p. 570. Thompson, in Annals and
Magazine of Natural History,
vol. viii., 1842, p. 494.
Sir J. Lubbock's
gamekeeper has repeatedly shot,
but how
often he could not say, one of
a pair of jays (Garrulus glandarius),
and has never failed shortly
afterwards to find the survivor
re-matched. Mr. Fox, Mr. F. Bond,
and others have shot one of a
pair of carrion-crows (Corvus
corone), but the nest was soon
again tenanted by a pair. These
birds are rather common; but
the peregrine-falcon (Falco peregrinus)
is rare, yet Mr. Thompson states
that in Ireland "if either an
old male or female be killed
in the breeding-season (not an
uncommon circumstance), another
mate is found within a very few
days, so that the eyries, notwithstanding
such casualties, are sure to
turn out their complement of
young." Mr. Jenner Weir has known
the same thing with the peregrine-falcons
at Beachy Head. The same observer
informs me that three kestrels
(Falco tinnunculus), all males,
were killed one after the other
whilst attending the same nest;
two of these were in mature plumage,
but the third was in the plumage
of the previous year. Even with
the rare golden eagle (Aquila
chrysaetos), Mr. Birkbeck was
assured by a trustworthy gamekeeper
in Scotland, that if one is killed,
another is soon found. So with
the white owl (Strix flammea), "the
survivor readily found a mate,
and the mischief went on."
White of Selborne,
who gives the case of the owl,
adds that
he knew a man, who from believing
that partridges when paired were
disturbed by the males fighting,
used to shoot them; and though
he had widowed the same female
several times, she always soon
found a fresh partner. This same
naturalist ordered the sparrows,
which deprived the house-martins
of their nests, to be shot; but
the one which was left, "be it
cock or hen, presently procured
a mate, and so for several times
following." I could add analogous
cases relating to the chaffinch,
nightingale, and redstart. With
respect to the latter bird (Phoenicura
ruticilla), a writer expresses
much surprise how the sitting
female could so soon have given
effectual notice that she was
a widow, for the species was
not common in the neighbourhood.
Mr. Jenner Weir has mentioned
to me a nearly similar case;
at Blackheath he never sees or
hears the note of the wild bullfinch,
yet when one of his caged males
has died, a wild one in the course
of a few days has generally come
and perched near the widowed
female, whose call-note is not
loud. I will give only one other
fact, on the authority of this
same observer; one of a pair
of starlings (Sturnus vulgaris)
was shot in the morning; by noon
a new mate was found; this was
again shot, but before night
the pair was complete; so that
the disconsolate widow or widower
was thrice consoled during the
same day. Mr. Engleheart also
informs me that he used during
several years to shoot one of
a pair of starlings which built
in a hole in a house at Blackheath;
but the loss was always immediately
repaired. During one season he
kept an account, and found that
he had shot thirty-five birds
from the same nest; these consisted
of both males and females, but
in what proportion he could not
say: nevertheless, after all
this destruction, a brood was
reared.*
* On the peregrine falcon, see
Thompson, Nat. Hist. of Ireland:
Birds, vol. i., 1849, p. 39.
On owls, sparrows, and partridges,
see White, Nat. Hist. of Selborne,
ed. of 1825, vol. i., p. 139.
On the Phoenicura, see Loudon's
Mag. of Nat. Hist., vol. vii.,
1834, p. 245. Brehm (Thierleben,
B. iv., s. 991) also alludes
to cases of birds thrice mated
during the same day.
These facts well deserve attention.
How is it that there are birds
enough ready to replace immediately
a lost mate of either sex? Magpies,
jays, carrion-crows, partridges,
and some other birds, are always
seen during the spring in pairs,
and never by themselves; and
these offer at first sight the
most perplexing cases. But birds
of the same sex, although of
course not truly paired, sometimes
live in pairs or in small parties,
as is known to be the case with
pigeons and partridges. Birds
also sometimes live in triplets,
as has been observed with starlings,
carrion-crows, parrots, and partridges.
With partridges two females have
been known to live with one male,
and two males with one female.
In all such cases it is probable
that the union would be easily
broken; and one of the three
would readily pair with a widow
or widower. The males of certain
birds may occasionally be heard
pouring forth their love-song
long after the proper time, shewing
that they have either lost or
never gained a mate. Death from
accident or disease of one of
a pair would leave the other
free and single; and there is
reason to believe that female
birds during the breeding-season
are especially liable to premature
death. Again, birds which have
had their nests destroyed, or
barren pairs, or retarded individuals,
would easily be induced to desert
their mates, and would probably
be glad to take what share they
could of the pleasures and duties
of rearing offspring although
not their own.* Such contingencies
as these probably explain most
of the foregoing cases.*(2) Nevertheless,
it is a strange fact that within
the same district, during the
height of the breeding-season,
there should be so many males
and females always ready to repair
the loss of a mated bird. Why
do not such spare birds immediately
pair together? Have we not some
reason to suspect, and the suspicion
has occurred to Mr. Jenner Weir,
that as the courtship of birds
appears to be in many cases prolonged
and tedious, so it occasionally
happens that certain males and
females do not succeed, during
the proper season, in exciting
each other's love, and consequently
do not pair? This suspicion will
appear somewhat less improbable
after we have seen what strong
antipathies and preferences female
birds occasionally evince towards
particular males.
* See White (Nat. Hist. of Selborne,
1825, vol. i., p. 140) on the
existence, early in the season,
of small coveys of male partridges,
of which fact I have heard other
instances. See Jenner, on the
retarded state of the generative
organs in certain birds, in Phil.
Transact., 1824. In regard to
birds living in triplets, I owe
to Mr. Jenner Weir the cases
of the starlings and parrots,
and to Mr. Fox, of partridges;
on carrion-crows, see the Field,
1868, p. 415. On various male
birds singing after the proper
period, see L. Jenyns, Observations
in Natural History, 1846, p.
87.
*(2) The following
case has been given (The Times,
Aug. 6,
1868) by the Rev. F. . Morris,
on the authority of the Hon.
and Rev. O. W. Forester. "The
gamekeeper here found a hawk's
nest this year, with five young
ones on it. He took four and
killed them, but left one with
its wings clipped as a decoy
to destroy the old ones by. They
were both shot next day, in the
act of feeding the young one,
and the keeper thought it was
done with. The next day he came
again and found two other charitable
hawks, who had come with an adopted
feeling to succour the orphan.
These two he killed, and then
left the nest. On returning afterwards
he found two more charitable
individuals on the same errand
of mercy. One of these he killed;
the other he also shot, but could
not find. No more came on the
like fruitless errand."
Mental Qualities of Birds, and
their Taste for the Beautiful.-
Before we further discuss the
question whether the females
select the more attractive males
or accept the first whom they
may encounter, it will be advisable
briefly to consider the mental
powers of birds. Their reason
is generally, and perhaps justly,
ranked as low; yet some facts
could be given* leading to an
opposite conclusion. Low powers
of reasoning, however, are compatible,
as we see with mankind, with
strong affections, acute perception,
and a taste for the beautiful;
and it is with these latter qualities
that we are here concerned. It
has often been said that parrots
become so deeply attached to
each other that when one dies
the other pines for a long time;
but Mr. Jenner Weir thinks that
with most birds the strength
of their affection has been much
exaggerated. Nevertheless when
one of a pair in a state of nature
has been shot, the survivor has
been heard for days afterwards
uttering a plaintive call; and
Mr. St. John gives various facts
proving the attachment of mated
birds.*(2) Mr. Bennett relates*(3)
that in China after a drake of
the beautiful mandarin teal had
been stolen, the duck remained
disconsolate, though sedulously
courted by another mandarin drake,
who displayed before her all
his charms. After an interval
of three weeks the stolen drake
was recovered, and instantly
the pair recognised each other
with extreme joy. On the other
hand, starlings, as we have seen,
may be consoled thrice in the
same day for the loss of their
mates. Pigeons have such excellent
local memories, that they have
been known to return to their
former homes after an interval
of nine months, yet, as I hear
from Mr. Harrison Weir, if a
pair which naturally would remain
mated for life be separated for
a few weeks during the winter,
and afterwards matched with other
birds, the two when brought together
again, rarely, if ever, recognise
each other.
* I am indebted
to Prof. Newton for the following
passage from
Mr. Adam's Travels of a Naturalist,
1870, p. 278. Speaking of Japanese
nut-hatches in confinement, he
says: "Instead of the more yielding
fruit of the yew, which is the
usual food of the nut-hatch of
Japan, at one time I substituted
hard hazel-nuts. As the bird
was unable to crack them, he
placed them one by one in his
water-glass, evidently with the
notion that they would in time
become softer- an interesting
proof of intelligence on the
part of these birds."
*(2) A Tour
in Sutherlandshire, vol. i.,
1849, p. 185. Dr. Buller
says (Birds of New Zealand, 1872,
p. 56) that a male king lory
was killed; and the female "fretted
and moped, refused her food,
and died of a broken heart."
*(3) Wanderings in New South
Wales, vol. ii., 1834, p. 62.
Birds sometimes
exhibit benevolent feelings;
they will feed the
deserted young ones even of distinct
species, but this perhaps ought
to be considered as a mistaken
instinct. They will feed, as
shewn in an earlier part of this
work, adult birds of their own
species which have become blind.
Mr. Buxton gives a curious account
of a parrot which took care of
a frost-bitten and crippled bird
of a distinct species, cleansed
her feathers, and defended her
from the attacks of the other
parrots which roamed freely about
his garden. It is a still more
curious fact that these birds
apparently evince some sympathy
for the pleasures of their fellows.
When a pair of cockatoos made
a nest in an acacia tree, "it
was ridiculous to see the extravagant
interest taken in the matter
by the others of the same species." These
parrots, also, evinced unbounded
curiosity, and clearly had "the
idea of property and possession."*
They have good memories, for
in the Zoological Gardens they
have plainly recognised their
former masters after an interval
of some months.
* "Acclimatization of Parrots",
by C. Buxton, M. P., Annals and
Mag. of Nat. Hist., Nov., 1868,
p. 381.
Birds possess
acute powers of observation.
Every mated bird,
of course, recognises its fellow.
Audubon states that a certain
number of mocking-thrushes (Mimus
polyglottus) remain all the year
round in Louisiana, whilst others
migrate to the Eastern States;
these latter, on their return,
are instantly recognised, and
always attacked, by their southern
brethren. Birds under confinement
distinguish different persons,
as is proved by the strong and
permanent antipathy or affection
which they shew, without any
apparent cause, towards certain
individuals. I have heard of
numerous instances with jays,
partridges, canaries, and especially
bullfinches. Mr. Hussey has described
in how extraordinary a manner
a tamed partridge recognised
everybody: and its likes and
dislikes were very strong. This
bird seemed "fond of gay colours,
and no new gown or cap could
be put on without catching his
attention."* Mr. Hewitt has described
the habits of some ducks (recently
descended from wild birds), which,
at the approach of a strange
dog or cat, would rush headlong
into the water, and exhaust themselves
in their attempts to escape;
but they knew Mr. Hewitt's own
dogs and cats so well that they
would lie down and bask in the
sun close to them. They always
moved away from a strange man,
and so they would from the lady
who attended them if she made
any great change in her dress.
Audubon relates that he reared
and tamed a wild turkey which
always ran away from any strange
dog; this bird escaped into the
woods, and some days afterwards
Audubon saw, as he thought, a
wild turkey, and made his dog
chase it; but, to his astonishment,
the bird did not run away, and
the dog, when he came up, did
not attack the bird, for they
mutually recognised each other
as old friends.*(2)
* The Zoologist, 1847-48, p.
1602.
*(2) Hewitt on wild ducks, Journal
of Horticulture, Jan. 13, 1863,
p. 39. Audubon on the wild turkey,
Ornithological Biography, vol.
i., p. 14. On the mocking-thrush,
ibid., vol. i., p. 110.
Mr. Jenner Weir is convinced
that birds pay particular attention
to the colours of other birds,
sometimes out of jealousy, and
sometimes as a sign of kinship.
Thus he turned a reed-bunting
(Emberiza schaeniculus), which
had acquired its black head-dress,
into his aviary, and the newcomer
was not noticed by any bird,
except by a bullfinch, which
is likewise black-headed. This
bullfinch was a very quiet bird,
and had never before quarrelled
with any of its comrades, including
another reed-bunting, which had
not as yet become black-headed:
but the reed-bunting with a black
head was so unmercifully treated
that it had to be removed. Spiza
cyanea, during the breeding-season,
is of a bright blue colour; and
though generally peaceable, it
attacked S. ciris, which has
only the head blue, and completely
scalped the unfortunate bird.
Mr. Weir was also obliged to
turn out a robin, as it fiercely
attacked all the birds in his
aviary with any red in their
plumage, but no other kinds;
it actually killed a red-breasted
cross-bill, and nearly killed
a goldfinch. On the other band,
he has observed that some birds,
when first introduced, fly towards
the species which resemble them
most in colour, and settle by
their sides.
As male birds
display their fine plumage
and other ornaments
with so much care before the
females, it is obviously probable
that these appreciate the beauty
of their suitors. It is, however,
difficult to obtain direct evidence
of their capacity to appreciate
beauty. When birds gaze at themselves
in a looking-glass (of which
many instances have been recorded)
we cannot feel sure that it is
not from jealousy of a supposed
rival, though this is not the
conclusion of some observers.
In other cases it is difficult
to distinguish between mere curiosity
and admiration. It is perhaps
the former feeling which, as
stated by Lord Lilford,* attracts
the ruff towards any bright object,
so that, in the Ionian Islands, "it
will dart down to a bright-coloured
handkerchief, regardless of repeated
shots." The common lark is drawn
down from the sky, and is caught
in large numbers, by a small
mirror made to move and glitter
in the sun. Is it admiration
or curiosity which leads the
magpie, raven, and some other
birds to steal and secrete bright
objects, such as silver articles
or jewels?
* The Ibis, vol. ii., 1860,
p. 344.
Mr. Gould states
that certain humming-birds
decorate the outsides
of their nests "with the utmost
taste; they instinctively fasten
thereon beautiful pieces of flat
lichen, the larger pieces in
the middle, and the smaller on
the part attached to the branch.
Now and then a pretty feather
is intertwined or fastened to
the outer sides, the stem being
always so placed that the feather
stands out beyond the surface." The
best evidence, however, of a
taste for the beautiful is afforded
by the three genera of Australian
bower-birds already mentioned.
Their bowers (see fig. 46), where
the sexes congregate and play
strange antics, are variously
constructed, but what most concerns
us is, that they are decorated
by the several species in a different
manner. The satin bower-bird
collects gaily-coloured articles,
such as the blue tail-feathers
of parrakeets, bleached bones
and shells, which it sticks between
the twigs or arranges at the
entrance. Mr. Gould found in
one bower a neatly-worked stone
tomahawk and a slip of blue cotton,
evidently procured from a native
encampment. These objects are
continually re-arranged, and
carried about by the birds whilst
at play. The bower of the spotted
bower-bird "is beautifully lined
with tall grasses, so disposed
that the heads nearly meet, and
the decorations are very profuse." Round
stones are used to keep the grass-stems
in their proper places, and to
make divergent paths leading
to the bower. The stones and
shells are often brought from
a great distance. The regent
bird, as described by Mr. Ramsay,
ornaments its short bower with
bleached land-shells belonging
to five or six species, and with "berries
of various colours, blue, red,
and black, which give it when
fresh a very pretty appearance.
Besides these there were several
newly-picked leaves and young
shoots of a pinkish colour, the
whole shewing a decided taste
for the beautiful." Well may
Mr. Gould say that "these highly
decorated halls of assembly must
be regarded as the most wonderful
instances of bird-architecture
yet discovered"; and the taste,
as we see, of the several species
certainly differs.*
* On the ornamented nests of
humming-birds, Gould, Introduction
to the Trochilidae, 1861, p.
19. On the bower-birds, Gould,
Handbook of the Birds of Australia,
1865, vol. i., pp. 444-461. Ramsay,
in the Ibis, 1867, p. 456.
Preference for
particular Males by the Females.-
Having made
these preliminary remarks on
the discrimination and taste
of birds, I will give all the
facts known to me which bear
on the preference shewn by the
female for particular males.
It is certain that distinct species
of birds occasionally pair in
a state of nature and produce
hybrids. Many instances could
be given: thus Macgillivray relates
how a male blackbird and female
thrush "fell in love with each
other," and produced offspring.*
Several years ago eighteen cases
had been recorded of the occurrence
in Great Britain of hybrids between
the black grouse and pheasant;*(2)
but most of these cases may perhaps
be accounted for by solitary
birds not finding one of their
own species to pair with. With
other birds, as Mr. Jenner Weir
has reason to believe, hybrids
are sometimes the result of the
casual intercourse of birds building
in close proximity. But these
remarks do not apply to the many
recorded instances of tamed or
domestic birds, belonging to
distinct species, which have
become absolutely fascinated
with each other, although living
with their own species. Thus
Waterton*(3) states that out
of a flock of twenty-three Canada
geese, a female paired with a
solitary bernicle gander, although
so different in appearance and
size; and they produced hybrid
offspring. A male wigeon (Mareca
penelope), living with females
of the same species, has been
known to pair with a pintail
duck, Querquedula acuta. Lloyd
describes the remarkable attachment
between a shield-drake (Tadorna
vulpanser) and a common duck.
Many additional instances could
be given; and the Rev. E. S.
Dixon remarks that "those who
have kept many different species
of geese together well know what
unaccountable attachments they
are frequently forming, and that
they are quite as likely to pair
and rear young with individuals
of a race (species) apparently
the most alien to themselves
as with their own stock."
* History of Brit. Birds, vol.
ii., p. 92.
*(2) Zoologist, 1853-1854, p.
3940.
*(3) Waterton, Essays on Nat.
Hist., 2nd series, pp. 42 and
117. For the following statements
see on the wigeon, Loudon's Mag.
of Nat. Hist., vol. ix., p. 616;
L. Lloyd, Scandinavian Adventures,
vol. i., 1854, p. 452. Dixon,
Ornamental and Domestic Poultry
p. 137; Hewitt, in Journal of
Horticulture, Jan. 13, 1863,
p. 40; Bechstein, Stubenvogel,
1840, s. 230. Mr. J. Jenner Weir
has lately given me an analogous
case with ducks of two species.
The Rev. W.
D. Fox informs me that he possessed
at the same
time a pair of Chinese geese
(Anser cygnoides), and a common
gander with three geese. The
two lots kept quite separate,
until the Chinese gander seduced
one of the common geese to live
with him. Moreover, of the young
birds hatched from the eggs of
the common geese, only four were
pure, the other eighteen proving
hybrids; so that the Chinese
gander seems to have had prepotent
charms over the common gander.
I will give only one other case;
Mr. Hewitt states that a wild
duck, reared in captivity "after
breeding a couple of seasons
with her own mallard, at once
shook him off on my placing a
male pintail on the water. It
was evidently a case of love
at first sight, for she swam
about the new-comer caressingly,
though he appeared evidently
alarmed and averse to her overtures
of affection. From that hour
she forgot her old partner. Winter
passed by, and the next spring
the pintail seemed to have become
a convert to her blandishments,
for they nested and produced
seven or eight young ones."
What the charm may have been
in these several cases, beyond
mere novelty, we cannot even
conjecture. Colour, however,
sometimes comes into play; for
in order to raise hybrids from
the siskin (Fringilla spinus)
and the canary, it is much the
best plan, according to Bechstein,
to place birds of the same tint
together. Mr. Jenner Weir turned
a female canary into his aviary,
where there were male linnets,
goldfinches, siskins, greenfinches,
chaffinches, and other birds,
in order to see which she would
choose; but there never was any
doubt, and the greenfinch carried
the day. They paired and produced
hybrid offspring.
The fact of the female preferring
to pair with one male rather
than with another of the same
species is not so likely to excite
attention, as when this occurs,
as we have just seen, between
distinct species. The former
cases can best be observed with
domesticated or confined birds;
but these are often pampered
by high feeding, and sometimes
have their instincts vitiated
to an extreme degree. Of this
latter fact I could give sufficient
proofs with pigeons, and especially
with fowls, but they cannot be
here related. Vitiated instincts
may also account for some of
the hybrid unions above mentioned;
but in many of these cases the
birds were allowed to range freely
over large ponds, and there is
no reason to suppose that they
were unnaturally stimulated by
high feeding.
With respect
to birds in a state of nature,
the first and most
obvious supposition which will
occur to every one is that the
female at the proper season accepts
the first male whom she may encounter;
but she has at least the opportunity
for exerting a choice, as she
is almost invariably pursued
by many males. Audubon- and we
must remember that he spent a
long life in prowling about the
forests of the United States
and observing the birds- does
not doubt that the female deliberately
chooses her mate; thus, speaking
of a woodpecker, he says the
hen is followed by half-a-dozen
gay suitors, who continue performing
strange antics, "until a marked
preference is shewn for one." The
female of the red-winged starling
(Agelaeus phaeniceus) is likewise
pursued by several males, "until,
becoming fatigued, she alights,
receives their addresses, and
soon makes a choice." He describes
also how several male night-jars
repeatedly plunge through the
air with astonishing rapidity,
suddenly turning, and thus making
a singular noise; "but no sooner
has the female made her choice
than the other males are driven
away." With one of the vultures
(Cathartes aura) of the United
States, parties of eight, ten,
or more males and females assemble
on fallen logs, "exhibiting the
strongest desire to please mutually," and
after many caresses, each male
leads off his partner on the
wing. Audubon likewise carefully
observed the wild flocks of Canada
geese (Anser canadensis), and
gives a graphic description of
their love-anties; he says that
the birds which had been previously
mated "renewed their courtship
as early as the month of January,
while the others would be contending
or coquetting for hours every
day, until all seemed satisfied
with the choice they had made,
after which, although they remained
together, any person could easily
perceive that they were careful
to keep in pairs. I have observed
also that the older the birds
the shorter were the preliminaries
of their courtship. The bachelors
and old maids whether in regret,
or not caring to be disturbed
by the bustle, quietly moved
aside and lay down at some distance
from the rest."* Many similar
statements with respect to other
birds could be cited from this
same observer.
* Audubon, Ornithological Biography,
vol. i., pp. 191, 349; vol. ii.,
pp. 42, 275; vol. iii., p. 2.
Turning now
to domesticated and confined
birds, I will commence
by giving what little I have
learnt respecting the courtship
of fowls. I have received long
letters on this subject from
Messrs. Hewitt and Tegetmeier,
and almost an essay from the
late Mr. Brent. It will be admitted
by every one that these gentlemen,
so well known from their published
works, are careful and experienced
observers. They do not believe
that the females prefer certain
males on account of the beauty
of their plumage; but some allowance
must be made for the artificial
state under which these birds
have long been kept. Mr. Tegetmeier
is convinced that a gamecock,
though disfigured by being dubbed
and with his hackles trimmed,
would be accepted as readily
as a male retaining all his natural
ornaments. Mr. Brent, however,
admits that the beauty of the
male probably aids in exciting
the female; and her acquiescence
is necessary. Mr. Hewitt is convinced
that the union is by no means
left to mere chance, for the
female almost invariably prefers
the most vigorous, defiant, and
mettlesome male; hence it is
almost useless, as he remarks, "to
attempt true breeding if a game-cock
in good health and condition
runs the locality, for almost
every hen on leaving the roosting-place
will resort to the game-cock,
even though that bird may not
actually drive away the male
of her own variety." Under ordinary
circumstances the males and females
of the fowl seem to come to a
mutual understanding by means
of certain gestures, described
to me by Mr. Brent. But hens
will often avoid the officious
attentions of young males. Old
hens, and hens of a pugnacious
disposition, as the same writer
informs me, dislike strange males,
and will not yield until well
beaten into compliance. Ferguson,
however, describes how a quarrelsome
hen was subdued by the gentle
courtship of a Shanghai cock.*
* Rare and Prize Poultry, 1854,
p. 27.
There is reason to believe that
pigeons of both sexes prefer
pairing with birds of the same
breed; and dovecot-pigeons dislike
all the highly improved breeds.*
Mr. Harrison Weir has lately
heard from a trustworthy observer,
who keeps blue pigeons, that
these drive away all other coloured
varieties, such as white, red,
and yellow; and from another
observer, that a female dun carrier
could not, after repeated trials,
be matched with a black male,
but immediately paired with a
dun. Again, Mr. Tegetmeier had
a female blue turbit that obstinately
refused to pair with two males
of the same breed, which were
successively shut up with her
for weeks; but on being let out
she would have immediately accepted
the first blue dragon that offered.
As she was a valuable bird, she
was then shut up for many weeks
with a silver (i. e., very pale
blue) male, and at last mated
with him. Nevertheless, as a
general rule, colour appears
to have little influence on the
pairing of pigeons. Mr. Tegetmeier,
at my request, stained some of
his birds with magenta, but they
were not much noticed by the
others.
* Variation of Animals and Plants
under Domestication, vol. ii.,
p. 103.
Female pigeons
occasionally feel a strong
antipathy towards
certain males, without any assignable
cause. Thus M.M. Boitard and
Corbie, whose experience extended
over forty-five years, state: "Quand
une femelle eprouve de l'antipathie
pour un male avec lequel on veut
l'accoupler, malgre tous les
feux de l'amour, malgre l'alpiste
et le chenevis dont on la nourrit
pour augmenter son ardeur malgre
un emprisonnement de six mois
et meme d'un an, elle refuse
constamment ses caresses; les
avances empressees, les agaceries,
les tournoiemens, les tendres
roucoulemens, rien ne peut lui
plaire ni l'emouvoir; gonflee,
boudeuse, blottie dans un coin
de sa prison, elle n'en sort
que pour boire et manger, ou
pour repousser avec une espece
de rage des caresses devenues
trop pressantes."* On the other
hand, Mr. Harrison Weir has himself
observed, and has heard from
several breeders, that a female
pigeon will occasionally take
a strong fancy for a particular
male, and will desert her own
mate for him. Some females, according
to another experienced observer,
Riedel,*(2) are of a profligate
disposition. and prefer almost
any stranger to their own mate.
Some amorous males, called by
our English fanciers "gay birds," are
so successful in their gallantries,
that, as Mr. H. Weir informs
me, they must be shut up on account
of the mischief which they cause.
* Boitard and
Corbie, Les Pigeons, &c.,
1824, p. 12. Prosper Lucas (Traite
de l'Hered. Nat., tom. ii., 1850,
p. 296) has himself observed
nearly similar facts with pigeons.
*(2) Die Taubenzucht, 1824,
s. 86.
Wild turkeys
in the United States, according
to Audubon, "sometimes
pay their addresses to the domesticated
females, and are generally received
by them with great pleasure." So
that these females apparently
prefer the wild to their own
males.*
* Ornithological Biography,
vol. i., p. 13. See to the same
effect, Dr. Bryant, in Allen's
Mammals and Birds of Florida,
p. 344.
Here is a more
curious case. Sir R. Heron
during many years
kept an account of the habits
of the peafowl, which he bred
in large numbers. He states that "the
hens have frequently great preference
to a particular peafowl. They
were all so fond of an old pied
cock, that one year, when he
was confined, though still in
view, they were constantly assembled
close to the trellice-walls of
his prison, and would not suffer
a japanned peacock to touch them.
On his being let out in the autumn,
the oldest of the hens instantly
courted him and was successful
in her courtship. The next year
he was shut up in a stable, and
then the hens all courted his
rival."* This rival was a japanned
or black-winged peacock, to our
eyes a more beautiful bird than
the common kind.
* Proceedings, Zoological Society,
1835, p. 54. The japanned peacock
is considered by Mr. Sclater
as a distinct species, and has
been named Pavo nigri-pennis;
but the evidence seems to me
to shew that it is only a variety.
Lichtenstein, who was a good
observer and had excellent opportunities
of observation at the Cape of
Good Hope, assured Rudolphi that
the female widow-bird (Chera
progne) disowns the male when
robbed of the long tail-feathers
with which he is ornamented during
the breeding-season. I presume
that this observation must have
been made on birds under confinement.*
Here is an analogous case; Dr.
Jaeger,*(2) director of the Zoological
Gardens of Vienna, states that
a male silver-pheasant, who had
been triumphant over all other
males and was the accepted lover
of the females, had his ornamental
plumage spoiled. He was then
immediately superseded by a rival,
who got the upper hand and afterwards
led the flock.
* Rudolphi, Beitrage zur Anthropologie,
1812, s. 184.
*(2) Die Darwin'sche Theorie,
und ihre Stellung zu Moral und
Religion, 1869, s. 59.
It is a remarkable fact, as
shewing how important colour
is in the courtship of birds,
that Mr. Boardman, a well-known
collector and observer of birds
for many years in the Northern
United States, has never in his
large experience seen an albino
paired with another bird; yet
he has had opportunities of observing
many albinos belonging to several
species.* It can hardly be maintained
that albinos in a state of nature
are incapable of breeding, as
they can be raised with the greatest
facility under confinement. It
appears, therefore, that we must
attribute the fact that they
do not pair to their rejection
by their normally coloured comrades.
* This statement is given by
Mr. A. Leith Adams, in his Field
and Forest Rambles, 1873, p.
76, and accords with his own
experience.
Female birds not only exert
a choice, but in some few cases
they court the male, or even
fight together for his possession.
Sir R. Heron states that with
peafowl, the first advances are
always made by the female; something
of the same kind takes place,
according to Audubon, with the
older females of the wild turkey.
With the capercailzie, the females
flit round the male whilst he
is parading at one of the places
of assemblage, and solicit his
attention.* We have seen that
a tame wild-duck seduced an unwilling
pintail drake after a long courtship.
Mr. Bartlett believes that the
Lophophorus, like many other
gallinaceous birds, is naturally
polygamous, but two females cannot
be placed in the same cage with
a male, as they fight so much
together. The following instance
of rivalry is more surprising
as it relates to bullfinches,
which usually pair for life.
Mr. Jenner Weir introduced a
dull-coloured and ugly female
into his aviary, and she immediately
attacked another mated female
so unmercifully that the latter
had to be separated. The new
female did all the courtship,
and was at last successful, for
she paired with the male; but
after a time she met with a just
retribution, for, ceasing to
be pugnacious, she was replaced
by the old female, and the male
then deserted his new and returned
to his old love.
* In regard to peafowl, see
Sir R. Heron, Proc. Zoolog. Soc.,
1835, p. 54, and the Rev. E.
S. Dixon, Ornamental Poultry,
1848, p. 8. For the turkey, Audubon,
ibid., p. 4. For the capercailzie,
Lloyd, Game Birds of Sweden,
1867, p. 23.
In all ordinary
cases the male is so eager
that he will accept
any female, and does not, as
far as we can judge, prefer one
to the other; but, as we shall
hereafter see, exceptions to
this rule apparently occur in
some few groups. With domesticated
birds, I have heard of only one
case of males shewing any preference
for certain females, namely,
that of the domestic cock, who,
according to the high authority
of Mr. Hewitt, prefers the younger
to the older hens. On the other
hand, in effecting hybrid unions
between the male pheasant and
common hens, Mr. Hewitt is convinced
that the pheasant invariably
prefers the older birds. He does
not appear to be in the least
influenced by their colour; but "is
most capricious in his attachments":*
from some inexplicable cause
he shews the most determined
aversion to certain hens, which
no care on the part of the breeder
can overcome. Mr. Hewitt informs
me that some hens are quite unattractive
even to the males of their own
species, so that they may be
kept with several cocks during
a whole season, and not one egg
out of forty or fifty will prove
fertile. On the other hand, with
the long-tailed duck (Harelda
glacialis), "it has been remarked," says
M. Ekstrom, "that certain females
are much more courted than the
rest. Frequently, indeed, one
sees an individual surrounded
by six or eight amorous males." Whether
this statement is credible, I
know not; but the native sportsmen
shoot these females in order
to stuff them as decoys.*(2)
* Mr. Hewitt, quoted in Tegetmeier's
Poultry Book, 1866, p. 165.
*(2) Quoted in Lloyd's Game
Birds of Sweden, p. 345.
With respect to female birds
feeling a preference for particular
males, we must bear in mind that
we can judge of choice being
exerted only by analogy. If an
inhabitant of another planet
were to behold a number of young
rustics at a fair courting a
pretty girl, and quarrelling
about her like birds at one of
their places of assemblage, he
would, by the eagerness of the
wooers to please her and to display
their finery, infer that she
had the power of choice. Now
with birds the evidence stands
thus: they have acute powers
of observation, and they seem
to have some taste for the beautiful
both in colour and sound. It
is certain that the females occasionally
exhibit, from unknown causes,
the strongest antipathies and
preferences for particular males.
When the sexes differ in colour
or in other ornaments the males
with rare exceptions are the
more decorated, either permanently
or temporarily during the breeding-season.
They sedulously display their
various ornaments, exert their
voices, and perform strange antics
in the presence of the females.
Even well-armed males, who, it
might be thought, would altogether
depend for success on the law
of battle, are in most cases
highly ornamented; and their
ornaments have been acquired
at the expense of some loss of
power. In other cases ornaments
have been acquired, at the cost
of increased risk from birds
and beasts of prey. With various
species many individuals of both
sexes congregate at the same
spot, and their courtship is
a prolonged affair. There is
even reason to suspect that the
males and females within the
same district do not always succeed
in pleasing each other and pairing.
What then are we to conclude
from these facts and considerations?
Does the male parade his charms
with so much pomp and rivalry
for no purpose? Are we not justified
in believing that the female
exerts a choice, and that she
receives the addresses of the
male who pleases her most? It
is not probable that she consciously
deliberates; but she is most
excited or attracted by the most
beautiful, or melodious, or gallant
males. Nor need it be supposed
that the female studies each
stripe or spot of colour; that
the peahen, for instance, admires
each detail in the gorgeous train
of the peacock- she is probably
struck only by the general effect.
Nevertheless, after hearing how
carefully the male Argus pheasant
displays his elegant primary
wing-feathers, and erects his
ocellated plumes in the right
position for their full effect;
or again, how the male goldfinch
alternately displays his gold-bespangled
wings, we ought not to feel too
sure that the female does not
attend to each detail of beauty.
We can judge, as already remarked,
of choice being exerted, only
from analogy; and the mental
powers of birds do not differ
fundamentally from ours. From
these various considerations
we may conclude that the pairing
of birds is not left to chance;
but that those males, which are
best able by their various charms
to please or excite the female,
are under ordinary circumstances
accepted. If this be admitted,
there is not much difficulty
in understanding how male birds
have gradually acquired their
ornamental characters. All animals
present individual differences,
and as man can modify his domesticated
birds by selecting the individuals
which appear to him the most
beautiful, so the habitual or
even occasional preference by
the female of the more attractive
males would almost certainly
lead to their modification; and
such modifications might in the
course of time be augmented to
almost any extent, compatible
with the existence of the species.
Variability of Birds, and especially
of their Secondary Sexual Characters.-
Variability and inheritance are
the foundations for the work
of selection. That domesticated
birds have varied greatly, their
variations being inherited, is
certain. That birds in a state
of nature have been modified
into distinct races is now universally
admitted.* Variations may be
divided into two classes; those
which appear to our ignorance
to arise spontaneously, and those
which are directly related to
the surrounding conditions, so
that all or nearly all the individuals
of the same species are similarly
modified. Cases of the latter
kind have recently been observed
with care by Mr. J. A. Allen,*(2)
who shews that in the United
States many species of birds
gradually become more strongly
coloured in proceeding southward,
and more lightly coloured in
proceeding westward to the arid
plains of the interior. Both
sexes seem generally to be affected
in a like manner, but sometimes
one sex more than the other.
This result is not incompatible
with the belief that the colours
of birds are mainly due to the
accumulation of successive variations
through sexual selection; for
even after the sexes have been
greatly differentiated, climate
might produce an equal effect
on both sexes, or a greater effect
on one sex than on the other,
owing to some constitutional
difference.
* According to Dr. Blasius (Ibis,
vol. ii., 1860, p. 297), there
are 425 indubitable species of
birds which breed in Europe,
besides sixty forms, which are
frequently regarded as distinct
species. Of the latter, Blasius
thinks that only ten are really
doubtful, and that the other
fifty ought to be united with
their nearest allies; but this
shews that there must be a considerable
amount of variation with some
of our European birds. It is
also an unsettled point with
naturalists, whether several
North American birds ought to
be ranked as specifically distinct
from the corresponding European
species. So again many North
American forms which until lately
were named as distinct species,
are now considered to be local
races.
*(2) Mammals
and Birds of East Florida,
also an Ornithological
Reconnaissance of Kansas, &c.
Notwithstanding the influence
of climate on the colours birds,
it is difficult to account for
the dull or dark tints of almost
all the species inhabiting certain
countries, for instance, the
Galapagos Islands under the equator,
the wide temperate plains of
Patagonia, and, as it appears,
Egypt (see Mr. Hartshorne in
the American Naturalist, 1873,
p. 747). These countries are
open, and afford little shelter
to birds; but it seems doubtful
whether the absence of brightly
coloured species can be explained
on the principle of protection,
for on the Pampas, which are
equally open, though covered
by green grass, and where the
birds would be equally exposed
to danger, many brilliant and
conspicuously coloured species
are common. I have sometimes
speculated whether the prevailing
dull tints of the scenery in
the above-named countries may
not have affected the appreciation
of bright colours by the birds
inhabiting them.
Individual differences
between the members of the
same species
are admitted by every one to
occur under a state of nature.
Sudden and strongly marked variations
are rare; it is also doubtful
whether if beneficial they would
often be preserved through selection
and transmitted to succeeding
generations.* Nevertheless, it
may be worth while to give the
few cases which I have been able
to collect, relating chiefly
to colour,- simple albinism and
melanism being excluded. Mr.
Gould is well known to admit
the existence of few varieties,
for he esteems very slight differences
as specific; yet he states*(2)
that near Bogota certain humming-birds
belonging to the genus Cynanthus
are divided into two or three
races or varieties, which differ
from each other in the colouring
of the tail- "some having the
whole of the feathers blue, while
others have the eight central
ones tipped with beautiful green." It
does not appear that intermediate
gradations have been observed
in this or the following cases.
In the males alone of one of
the Australian parrakeets "the
thighs in some are scarlet, in
others grass-green." In another
parrakeet of the same country "some
individuals have the band across
the wing-coverts bright-yellow,
while in others the same part
is tinged with red.*(3) In the
United States some few of the
males of the scarlet tanager
(Tanagra rubra) have "a beautiful
transverse band of glowing red
on the smaller wing-coverts";*(4)
but this variation seems to be
somewhat rare, so that its preservation
through sexual selection would
follow only under usually favourable
circumstances. In Bengal the
honey buzzard (Pernis cristata)
has either a small rudimental
crest on its head, or none at
all: so slight a difference,
however, would not have been
worth notice, had not this same
species possessed in southern
India a well-marked occipital
crest formed of several graduated
feathers."*(5)
* I had always perceived (Origin
of Species) that rare and strongly-marked
deviations of structure, deserving
to be called monstrosities, could
seldom be preserved through natural
selection, and that the preservation
of even highly-beneficial variations
would depend to a certain extent
on chance. I had also fully appreciated
the importance of mere individual
differences, and this led me
to insist so strongly on the
importance of that unconscious
form of selection by man, which
follows from the preservation
of the most valued individuals
of each breed, without any intention
on his part to modify the characters
of the breed. But until I read
an able article in the North
British Review (March 1867, p.
289, et seq.), which has been
of more use to me than any other
Review, I did not see how great
the chances were against the
preservation of variations, whether
slight or strongly pronounced,
occurring only in single individuals.
*(2) Introduction to the Trochlidae,
p. 102.
*(3) Gould, Handbook of Birds
of Australia, vol. ii., pp. 32
and 68.
*(4) Audubon, Ornithological
Biography, 1838, vol. iv., p.
389.
*(5) Jerdon, Birds of India,
vol. i., p. 108; and Mr. Blyth,
in Land and Water, 1868, p. 381.
The following case is in some
respects more interesting. A
pied variety of the raven, with
the head, breast, abdomen, and
parts of the wings and tail-feathers
white, is confined to the Feroe
Islands. It is not very rare
there, for Graba saw during his
visit from eight to ten living
specimens. Although the characters
of this variety are not quite
constant, yet it has been named
by several distinguished ornithologists
as a distinct species. The fact
of the pied birds being pursued
and persecuted with much clamour
by the other ravens of the island
was the chief cause which led
Brunnich to conclude that they
were specifically distinct; but
this is now known to be an error.*
This case seems analogous to
that lately given of albino birds
not pairing from being rejected
by their comrades.
* Graba, Tagebuch Reise nach
Faro, 1830, ss. 51-54. Macgillivray,
History of British Birds, vol.
iii., p. 745. Ibis, vol. v.,
1863, p. 469.
In various parts of the northern
seas a remarkable variety of
the common guillemot (Uria troile)
is found; and in Feroe, one out
of every five birds, according
to Graba's estimation, presents
this variation. It is characterised*
by a pure white ring round the
eye, with a curved narrow white
line, an inch and a half in length,
extending back from the ring.
This conspicuous character has
caused the bird to be ranked
by several ornithologists as
a distinct species under the
name of U. lacrymans, but it
is now known to be merely a variety.
It often pairs with the common
kind, yet intermediate gradations
have never been seen; nor is
this surprising, for variations
which appear suddenly, are often,
as I have elsewhere shewn,*(2)
transmitted either unaltered
or not at all. We thus see that
two distinct forms of the same
species may co-exist in the same
district, and we cannot doubt
that if the one had possessed
any advantage over the other,
it would soon have been multiplied
to the exclusion of the latter.
If, for instance, the male pied
ravens, instead of being persecuted
by their comrades, had been highly
attractive (like the above pied
peacock) to the black female
ravens their numbers would have
rapidly increased. And this would
have been a case of sexual selection.
* Graba, ibid., s. 54. Macgillivray,
ibid., vol. v., p. 327.
*(2) Variation of Animals and
Plants under Domestication, vol.
ii., p. 92.
With respect to the slight individual
differences which are common,
in a greater or less degree,
to all the members of the same
species, we have every reason
to believe that they are by far
the most important for the work
of selection. Secondary sexual
characters are eminently liable
to vary, both with animals in
a state of nature and under domestication.*
There is also reason to believe,
as we have seen in our eighth
chapter, that variations are
more apt to occur in the male
than in the female sex. All these
contingencies are highly favourable
for sexual selection. Whether
characters thus acquired are
transmitted to one sex or to
both sexes, depends, as we shall
see in the following chapter,
on the form of inheritance which
prevails.
* On these points see also Variation
of Animals and Plants under Domestication,
vol. i., p. 253; vol ii., pp.
73, 75.
It is sometimes difficult to
form an opinion whether certain
slight differences between the
sexes of birds are simply the
result of variability with sexually-limited
inheritance, without the aid
of sexual selection, or whether
they have been augmented through
this latter process. I do not
here refer to the many instances
where the male displays splendid
colours or other ornaments, of
which the female partakes to
a slight degree; for these are
almost certainly due to characters
primarily acquired by the male
having been more or less transferred
to the female. But what are we
to conclude with respect to certain
birds in which, for instance,
the eyes differ slightly in colour
in the two sexes?* In some cases
the eyes differ conspicuously;
thus with the storks of the genus
Xenorhynchus, those of the male
are blackish-hazel, whilst those
of the females are gamboge-yellow;
with many hornbills (Buceros),
as I hear from Mr. Blyth,*(2)
the males have intense crimson
eyes, and those of the females
are white. In the Buceros bicornis,
the hind margin of the casque
and a stripe on the crest of
the beak are black in the male,
but not so in the female. Are
we to suppose that these black
marks and the crimson colour
of the eyes have been preserved
or augmented through sexual selection
in the males? This is very doubtful;
for Mr. Bartlett shewed me in
the Zoological Gardens that the
inside of the mouth of this Buceros
is black in the male and flesh-coloured
in the female; and their external
appearance or beauty would not
be thus affected. I observed
in Chile*(3) that the iris in
the condor, when about a year
old, is dark-brown, but changes
at maturity into yellowish-brown
in the male, and into bright
red in the female. The male has
also a small, longitudinal, leaden-coloured,
fleshy crest or comb. The comb
of many gallinaceous birds is
highly ornamental, and assumes
vivid colours during the act
of courtship; but what are we
to think of the dull-coloured
comb of the condor, which does
not appear to us in the least
ornamental? The same question
may be asked in regard to various
other characters, such as the
knob on the base of the beak
of the Chinese goose (Anser cygnoides),
which is much larger in the male
than in the female. No certain
answer can be given to these
questions; but we ought to be
cautious in assuming that knobs
and various fleshy appendages
cannot be attractive to the female,
when we remember that with savage
races of man various hideous
deformities- deep scars on the
face with the flesh raised into
protuberances, the septum of
the nose pierced by sticks or
bones, holes in the ears and
lips stretched widely open- are
all admired as ornamental.
* See, for instance, on the
irides of a Podica and Gallicrex
in Ibis, vol. ii., 1860, p. 206;
and vol. V., 1863, p. 426.
*(2) See also Jerdon, Birds
of India, vol. i., pp. 243-245
*(3) Zoology of the Voyage of
H. M. S. Beagle, 1841, p. 6.
Whether or not unimportant differences
between the sexes, such as those
just specified, have been preserved
through sexual selection, these
differences, as well as all others,
must primarily depend on the
laws of variation. On the principle
of correlated development, the
plumage often varies on different
parts of the body, or over the
whole body, in the same manner.
We see this well illustrated
in certain breeds of the fowl.
In all the breeds the feathers
on the neck and loins of the
males are elongated, and are
called hackles; now when both
sexes acquire a top-knot, which
is a new character in the genus,
the feathers on the head of the
male become hackle-shaped, evidently
on the principle of correlation;
whilst those on the head of the
female are of the ordinary shape.
The colour also of the hackles
forming the top-knot of the male,
is often correlated with that
of the hackles on the neck and
loins, as may be seen by comparing
these feathers in the golden
and silver-spangled Polish, the
Houdans, and Creve-coeur breeds.
In some natural species we may
observe exactly the same correlation
in the colours of these same
feathers, as in the males of
the splendid gold and Amherst
pheasants.
The structure of each individual
feather, generally causes any
change in its colouring to be
symmetrical; we see this in the
various laced, spangled, and
pencilled breeds of the fowl;
and on the principle of correlation
the feathers over the whole body
are often coloured in the same
manner. We are thus enabled without
much trouble to rear breeds with
their plumage marked almost as
symmetrically as in natural species.
In laced and spangled fowls the
coloured margins of the feathers
are abruptly defined; but in
a mongrel raised by me from a
black Spanish cock glossed with
green, and a white game-hen,
all the feathers were greenish-black,
excepting towards their extremities,
which were yellowish-white; but
between the white extremities
and the black bases, there was
on each feather a symmetrical,
curved zone of dark-brown. In
some instances the shaft of the
feather determines the distribution
of the tints; thus with the body-feathers
of a mongrel from the same black
Spanish cock and a silver-spangled
Polish hen, the shaft, together
with a narrow space on each side,
was greenish-black, and this
was surrounded by a regular zone
of dark-brown, edged with brownish-white.
In these cases we have feathers
symmetrically shaded, like those
which give so much elegance to
the plumage of many natural species.
I have also noticed a variety
of the common pigeon with the
wing-bars symmetrically zoned
with three bright shades, instead
of being simply black on a slaty-blue
ground, as in the parent-species.
In many groups of birds the
plumage is differently coloured
in the several species, yet certain
spots, marks, or stripes are
retained by all. Analogous cases
occur with the breeds of the
pigeon, which usually retain
the two wing-bars, though they
may be coloured red, yellow,
white, black, or blue, the rest
of the plumage being of some
wholly different tint. Here is
a more curious case, in which
certain marks are retained, though
coloured in a manner almost exactly
the opposite of what is natural;
the aboriginal pigeon has a blue
tail, with the terminal halves
of the outer webs of the two
outer tail feathers white; now
there is a sub-variety having
a white instead of a blue tail,
with precisely that part black
which is white in the parent-species.*
* Bechstein, Naturgeschichte
Deutschlands, B. iv., 1795, s.
31, on a sub-variety of the monck
pigeon.
Formation and
Variability of the Ocelli or
eye-like Spots
on the Plumage of Birds.- As
no ornaments are more beautiful
than the ocelli on the feathers
of various birds, on the hairy
coats of some mammals, on the
scales of reptiles and fishes,
on the skin of amphibians, on
the wings of many Lepidoptera
and other insects, they deserve
to be especially noticed. An
ocellus consists of a spot within
a ring of another colour, like
the pupil within the iris, but
the central spot is often surrounded
by additional concentric zones.
The ocelli on the tail-coverts
of the peacock offer a familiar
example, as well as those on
the wings of the peacock-butterfly
(Vanessa). Mr. Trimen has given
me a description of a S. African
moth (Gynanisa isis), allied
to our emperor moth, in which
a magnificent ocellus occupies
nearly the whole surface of each
hinder wing; it consists of a
black centre, including a semi-transparent
crescent-shaped mark, surrounded
by successive, ochre-yellow,
black, ochre-yellow, pink, white,
pink, brown, and whitish zones.
Although we do not know the steps
by which these wonderfully beautiful
and complex ornaments have been
developed, the process has probably
been a simple one, at least with
insects; for, as Mr. Trimen writes
to me, "no characters of mere
marking or colouration are so
unstable in the Lepidoptera as
the ocelli, both in number and
size." Mr. Wallace, who first
called my attention to this subject,
shewed me a series of specimens
of our common meadow-brown butterfly
(Hipparchia janira) exhibiting
numerous gradations from a simple
minute black spot to an elegantly-shaded
ocellus. In a S. African butterfly
(Cyllo leda, Linn.), belonging
to the same family, the ocelli
are even still more variable.
In some specimens (see A, fig.
53) large spaces on the upper
surface of the wings are coloured
black, and include irregular
white marks; and from this state
a complete gradation can be traced
into a tolerably perfect ocellus
(A1), and this results from the
contraction of the irregular
blotches of colour. In another
series of specimens a gradation
can be followed from excessively
minute white dots, surrounded
by a scarcely visible black line
(B), into perfectly symmetrical
and large ocelli (B1).* In cases
like these, the development of
a perfect ocellus does not require
a long course of variation and
selection.
* This woodcut has been engraved
from a beautiful drawing, most
kindly made for me by Mr. Trimen;
see also his description of the
wonderful amount of variation
in the coloration and shape of
the wings this butterfly, in
his Rhopalocera Africae, Australis,
p. 186.
With birds and many other animals,
it seems to follow from the comparison
of allied species that circular
spots are often generated by
the breaking up and contraction
of stripes. In the tragopan pheasant
faint white lines in the female
represent the beautiful white
spots in the male;* and something
of the same kind may be observed
in the two sexes of the Argus
pheasant. However this may be,
appearances strongly favour the
belief that on the one hand,
a dark spot is often formed by
the colouring matter being drawn
towards a central point from
a surrounding zone, which latter
is thus rendered lighter; and,
on the other hand, that a white
spot is often formed by the colour
being driven away from a central
point, so that it accumulates
in a surrounding darker zone.
In either case an ocellus is
the result. The colouring matter
seems to be a nearly constant
quantity, but is redistributed,
either centripetally or centrifugally.
The feathers of the common guinea-fowl
offer a good instance of white
spots surrounded by darker zones;
and wherever the white spots
are large and stand near each
other, the surrounding dark zones
become confluent. In the same
wing-feather of the Argus pheasant
dark spots may be seen surrounded
by a pale zone, and white spots
by a dark zone. Thus the formation
of an ocellus in its most elementary
state appears to be a simple
affair. By what further steps
the more complex ocelli, which
are surrounded by many successive
zones Of colour, have been generated,
I will not pretend to say. But
the zoned feathers of the mongrels
from differently coloured fowls,
and the extraordinary variability
of the ocelli on many Lepidoptera,
lead us to conclude that their
formation is not a complex process,
but depends on some slight and
graduated change in the nature
of the adjoining tissues.
* Jerdon, Birds of India, vol.
iii., p. 517.
Gradation of
Secondary Sexual Characters.-
Cases of gradation
are important, as shewing us
that highly complex ornaments
may be acquired by small successive
steps. In order to discover the
actual steps by which the male
of any existing bird has acquired
his magnificent colours or other
ornaments, we ought to behold
the long line of his extinct
progenitors; but this is obviously
impossible. We may, however,
generally gain a clue by comparing
all the species of the same group,
if it be a large one; for some
of them will probably retain,
at least partially, traces of
their former characters. Instead
of entering on tedious details
respecting various groups, in
which striking instances of gradation
could be given, it seems the
best plan to take one or two
strongly marked cases, for instance
that of the peacock, in order
to see if light can be thrown
on the steps by which this bird
bas become so splendidly decorated.
The peacock is chiefly remarkable
from the extraordinary length
of his tail-coverts; the tail
itself not being much elongated.
The barbs along nearly the whole
length of these feathers stand
separate or are decomposed; but
this is the case with the feathers
of many species, and with some
varieties of the domestic fowl
and pigeon. The barbs coalesce
towards the extremity of the
shaft forming the oval disc or
ocellus, which is certainly one
of the most beautiful objects
in the world. It consists of
an iridescent, intensely blue,
indented centre, surrounded by
a rich green zone, this by a
broad coppery-brown zone, and
this by five other narrow zones
of slightly different iridescent
shades. A trifling character
in the disc deserves notice;
the barbs, for a space along
one of the concentric zones are
more or less destitute of their
barbules, so that a part of the
disc is surrounded by an almost
transparent zone, which gives
it a highly finished aspect.
But I have elsewhere described*
an exactly analogous variation
in the hackles of a sub-variety
of the game-cock, in which the
tips, having a metallic lustre, "are
separated from the lower part
of the feather by a symmetrically
shaped transparent zone, composed
of the naked portions of the
barbs." The lower margin or base
of the dark-blue centre of the
ocellus is deeply indented on
the line of the shaft. The surrounding
zones likewise shew traces, as
may be seen in the drawing (see
fig. 54), of indentations, or
rather breaks. These indentations
are common to the Indian and
Javan peacocks (Pavo cristatus
and P. muticus); and they seem
to deserve particular attention,
as probably connected with the
development of the ocellus; but
for a long time I could not conjecture
their meaning.
* Variation of Animals and Plants
under Domestication, vol. i.,
p. 254.
If we admit the principle of
gradual evolution, there must
formerly have existed many species
which presented every successive
step between the wonderfully
elongated tail-coverts of the
peacock and the short tail-coverts
of all ordinary birds; and again
between the magnificent ocelli
of the former, and the simpler
ocelli or mere coloured spots
on other birds; and so with all
the other characters of the peacock.
Let us look to the allied Gallinaceae
for any still-existing gradations.
The species and sub-species of
Polyplectron inhabit countries
adjacent to the native land of
the peacock; and they so far
resemble this bird that they
are sometimes called peacock-pheasants.
I am also informed by Mr. Bartlett
that they resemble the peacock
in their voice and in some of
their habits. During the spring
the males, as previously described,
strut about before the comparatively
plain-coloured females, expanding
and erecting their tail and wing-feathers,
which are ornamented with numerous
ocelli. I request the reader
to turn back to the drawing (see
fig. 51) of a Polyplectron; In
P. napoleonis the ocelli are
confined to the tail, and the
back is of a rich metallic blue;
in which respects this species
approaches the Java peacock P.
hardwickii possesses a peculiar
topknot, which is also somewhat
like that of the Java peacock.
In all species the ocelli on
the wings and tail are either
circular or oval, and consist
of a beautiful, iridescent, greenish-blue
or greenish-purple disc, with
a black border. This border in
P. chinquis shades into brown.
edged with cream colour, so that
the ocellus is here surrounded
with variously shaded, though
not bright, concentric zones.
The unusual length of the tail-coverts
is another remarkable character
in Polyplectron; for in some
of the species they are half,
and in others two-thirds as long
as the true tail-feathers. The
tail-coverts are ocellated as
in the peacock. Thus the several
species of Polyplectron manifestly
make a graduated approach to
the peacock in the length of
their tail-coverts, in the zoning
of the ocelli, and in some other
characters.
Notwithstanding this approach,
the first species of Polyplectron
which I examined almost made
me give up the search; for I
found not only that the true
tail-feathers, which in the peacock
are quite plain, were ornamented
with ocelli, but that the ocelli
on all the feathers differed
fundamentally from those of the
peacock, in there being two on
the same feather (see fig. 55),
one on each side of the shaft.
Hence I concluded that the early
progenitors of the peacock could
not have resembled a Polyplectron.
But on continuing my search,
I observed that in some of the
species the two ocelli stood
very near each other; that in
the tail-feathers of P. hardwickii
they touched each other; and,
finally, that on the tail-coverts
of this same species as well
as of P. malaccense (see fig.
56) they were actually confluent.
As the central part alone is
confluent, an indentation is
left at both the upper and lower
ends; and the surrounding coloured
zones are likewise indented.
A single ocellus is thus formed
on each tail-covert, though still
plainly betraying its double
origin. These confluent ocelli
differ from the single ocelli
of the peacock in having an indentation
at both ends, instead of only
at the lower or basal end. The
explanation, however, of this
difference is not difficult;
in some species of Polyplectron
the two oval ocelli on the same
feather stand parallel to each
other; in other species (as in
P. chinquis) they converge towards
one end; now the partial confluence
of two convergent ocelli would
manifestly leave a much deeper
indentation at the divergent
than at the convergent end. It
is also manifest that if the
convergence were strongly pronounced
and the confluence complete,
the indentation at the convergent
end would tend to disappear.
The tail-feathers in both species
of the peacock are entirely destitute
of ocelli, and this apparently
is related to their being covered
up and concealed by the long
tail-coverts. In this respect
they differ remarkably from the
tail-feathers of Polyplectron,
which in most of the species
are ornamented with larger ocelli
than those on the tail-coverts.
Hence I was led carefully to
examine the tail-feathers of
the several species, in order
to discover whether their ocelli
shewed any tendency to disappear;
and to my great satisfaction,
this appeared to be so. The central
tail-feathers of P. napoleonis
have the two ocelli on each side
of the shaft perfectly developed;
but the inner ocellus becomes
less and less conspicuous on
the more exterior tail-feathers,
until a mere shadow or rudiment
is left on the inner side of
the outermost feather. Again,
in P. malaccense, the ocelli
on the tail-coverts are, as we
have seen, confluent; and these
feathers are of unusual length,
being two-thirds of the length
of the tail-feathers, so that
in both these respects they approach
the tail-coverts of the peacock.
Now in P. malaccense, the two
central tail-feathers alone are
ornamented, each with two brightly-coloured
ocelli, the inner ocellus having
completely disappeared from all
the other tail-feathers. Consequently
the tail-coverts and tail-feathers
of this species of Polyplectron
make a near approach in structure
and ornamentation to the corresponding
feathers of the peacock.
As far, then, as gradation throws
light on the steps by which the
magnificent train of the peacock
has been acquired, hardly anything
more is needed. If we picture
to ourselves a progenitor of
the peacock in an almost exactly
intermediate condition between
the existing peacock, with his
enormously elongated tail-coverts,
ornamented with single ocelli,
and an ordinary gallinaceous
bird with short tail-coverts,
merely spotted with some colour,
we shall see a bird allied to
Polyplectron- that is, with tail-coverts,
capable of erection and expansion,
ornamented with two partially
confluent ocelli, and long enough
almost to conceal the tail-feathers,
the latter having already partially
lost their ocelli. The indentation
of the central disc and of the
surrounding zones of the ocellus,
in both species of peacock, speaks
plainly in favour of this view,
and is otherwise inexplicable.
The males of Polyplectron are
no doubt beautiful birds, but
their beauty, when viewed from
a little distance, cannot be
compared with that of the peacock.
Many female progenitors of the
peacock must, during a long line
of descent, have appreciated
this superiority; for they have
unconsciously, by the continued
preference for the most beautiful
males, rendered the peacock the
most splendid of living birds.
Argus pheasant.- Another excellent
case for investigation is offered
by the ocelli on the wing-feathers
of the Argus pheasant, which
are shaded in so wonderful a
manner as to resemble balls lying
loose within sockets, and consequently
differ from ordinary ocelli.
No one, I presume, will attribute
the shading, which has excited
the admiration of many experienced
artists, to chance- to the fortuitous
concourse of atoms of colouring
matter. That these ornaments
should have been formed through
the selection of many successive
variations, not one of which
was originally intended to produce
the ball-and-socket effect, seems
as incredible as that one of
Raphael's Madonnas should have
been formed by the selection
of chance daubs of paint made
by a long succession of young
artists, not one of whom intended
at first to draw the human figure.
In order to discover how the
ocelli have been developed, we
cannot look to a long line of
progenitors, nor to many closely-allied
forms, for such do not now exist.
But fortunately the several feathers
on the wing suffice to give us
a clue to the problem, and they
prove to demonstration that a
gradation is at least possible
from a mere spot to a finished
ball-and-socket ocellus.
The wing-feathers, bearing the
ocelli, are covered with dark
stripes (see fig. 57) or with
rows of dark spots (see fig.
59), each stripe or row of spots
running obliquely down the outer
side of the shaft to one of the
ocelli. The spots are generally
elongated in a line transverse
to the row in which they stand.
They often become confluent either
in the line of the row- and then
they form a longitudinal stripe-
or transversely, that is, with
the spots in the adjoining rows,
and then they form transverse
stripes. A spot sometimes breaks
up into smaller spots, which
still stand in their proper places.
It will be convenient first
to describe a perfect ball-and-socket
ocellus. This consists of an
intensely black circular ring,
surrounding a space shaded so
as exactly to resemble a ball.
The figure here given has been
admirably drawn by Mr. Ford and
well engraved, but a woodcut
cannot exhibit the exquisite
shading of the original. The
ring is almost always slightly
broken or interrupted (see fig.
57) at a point in the upper half,
a little to the right of and
above the white shade on the
enclosed ball; it is also sometimes
broken towards the base on the
right hand. These little breaks
have an important meaning. The
ring is always much thickened,
with the edges ill-defined towards
the left-hand upper corner, the
feather being beld erect, in
the position in which it is here
drawn. Beneath this thickened
part there is on the surface
of the ball an oblique almost
pure-white mark, which shades
off downwards into a pale-leaden
hue, and this into yellowish
and brown tints, which insensibly
become darker and darker towards
the lower part of the ball. It
is this shading which gives so
admirably the effect of light
shining on a convex surface.
If one of the balls be examined,
it will be seen that the lower
part is of a brown tint and is
indistinctly separated by a curved
oblique line from the upper part
which is yellower and more leaden;
this curved oblique line runs
at right angles to the longer
axis of the white patch of light,
and indeed of all the shading;
but this difference in colour,
which cannot of course be shewn
in the woodcut, does not in the
least interfere with the perfect
shading of the ball. It should
be particularly observed that
each ocellus stands in obvious
connection either with a dark
stripe, or with a longitudinal
row of dark spots for both occur
indifferently on the same feather.
Thus in fig. 57 (see figure)
stripe A runs to ocellus (a);
B runs to ocellus (b); stripe
C is broken in the upper part,
and runs down to the next succeeding
ocellus, not represented in the
woodcut; D to the next lower
one, and so with the stripes
E and F. Lastly, the several
ocelli are separated from each
other by a pale surface bearing
irregular black marks.
I will next describe the other
extreme of the series, namely,
the first trace of an ocellus.
The short secondary wing-feather
(see fig. 58), nearest to the
body, is marked like the other
feathers, with oblique, longitudinal,
rather irregular, rows of very
dark spots. The basal spot, or
that nearest the shaft, in the
five lower rows (excluding the
lowest one) is a little larger
than the other spots of the same
row, and a little more elongated
in a transverse direction. It
differs also from the other spots
by being bordered on its upper
side with some dull fulvous shading.
But this spot is not in any way
more remarkable than those on
the plumage of many birds, and
might easily be overlooked. The
next higher spot does not differ
at all from the upper ones in
the same row. The larger basal
spots occupy exactly the same
relative position on these feathers
as do the perfect ocelli on the
longer wing-feathers.
By looking to
the next two or three succeeding
wing-feathers,
an absolutely insensible gradation
can be traced from one of the
last described basal spots, together
with the next higher one in the
same row, to a curious ornament,
which cannot be called an ocellus,
and which I will name, from the
want of a better term, an "elliptic
ornament." These are shewn in
the accompanying figure (see
fig. 59). We here see several
oblique rows, A, B, C, D, &c.
(see the lettered diagram on
the right hand), of dark spots
of the usual character. Each
row of spots runs down to and
is connected with one of the
elliptic ornaments, in exactly
the same manner as each stripe
in fig. 57 (see figure) runs
down to, and is connected with,
one of the ball-and-socket ocelli.
Looking to any one row, for instance,
B, in fig. 59 (see figure), the
lowest mark (b) is thicker and
considerably longer than the
upper spots, and has its left
extremity pointed and curved
upwards. This black mark is abruptly
bordered on its upper side by
a rather broad space of richly
shaded tints, beginning with
a narrow brown zone, which passes
into orange, and this into a
pale leaden tint, with the end
towards the shaft much paler.
These shaded tints together fill
up the whole inner space of the
elliptic ornament. The mark (b)
corresponds in every respect
with the basal shaded spot of
the simple feather described
in the last paragraph (see fig.
58), but is more highly developed
and more brightly coloured. Above
and to the right of this spot
(see b, fig. 59), with its bright
shading, there is a long narrow,
black mark (c), belonging to
the same row, and which is arched
a little downwards so as to face
(b). This mark is sometimes broken
into two portions. It is also
narrowly edged on the lower side
with a fulvous tint. To the left
of and above (c), in the same
oblique direction, but always
more or less distinct from it,
there is another black mark (d).
This mark is generally sub-triangular
and irregular in shape, but in
the one lettered in the diagram
it is unusually narrow, elongated,
and regular. It apparently consists
of a lateral and broken prolongation
of the mark (c), together with
its confluence with a broken
and prolonged part of the next
spot above; but I do not feel
sure of this. These three marks,
b, c, and d, with the intervening
bright shades, form together
the so-called elliptic ornament.
These ornaments placed parallel
to the shaft, manifestly correspond
in position with the ball-and-socket
ocelli. Their extremely elegant
appearance cannot be appreciated
in the drawing, as the orange
and leaden tints, contrasting
so well with the black marks,
cannot be shewn.
Between one of the elliptic
ornaments and a perfect ball-and-socket
ocellus, the gradation is so
perfect that it is scarcely possible
to decide when the latter term
ought to be used. The passage
from the one into the other is
effected by the elongation and
greater curvature in opposite
directions of the lower black
mark (see b, fig. 59), and more
especially of the upper one (c),
together with the contraction
of the elongated sub-triangular
or narrow mark (d), so that at
last these three marks become
confluent, forming an irregular
elliptic ring. This ring is gradually
rendered more and more circular
and regular, increasing at the
same time in diameter. I have
here given a drawing (see fig.
60) of the natural size of an
ocellus not as yet quite perfect.
The lower part of the black ring
is much more curved than is the
lower mark in the elliptic ornament
(see b, fig. 59). The upper part
of the ring consists of two or
three separate portions; and
there is only a trace of the
thickening of the portion which
forms the black mark above the
white shade. This white shade
itself is not as yet much concentrated;
and beneath it the surface is
brighter coloured than in a perfect
ball-and-socket ocellus. Even
in the most perfect ocelli traces
of the junction of three or four
elongated black marks, by which
the ring has been formed, may
often be detected. The irregular
sub-triangular or narrow mark
(see d, fig. 59), manifestly
forms, by its contraction and
equalisation, the thickened portion
of the ring above the white shade
on a perfect ball-and-socket
ocellus. The lower part of the
ring is invariably a little thicker
than the other parts (see fig.
57), and this follows from the
lower black mark of the elliptic
ornament (see b, fig. 59) having
originally been thicker than
the upper mark (c). Every step
can be followed in the process
of confluence and modification;
and the black ring which surrounds
the ball of the ocellus is unquestionably
formed by the union and modification
of the three black marks, b,
c, d, of the elliptic ornament.
The irregular zigzag black marks
between the successive ocelli
(see again fig. 57) are plainly
due to the breaking up of the
somewhat more regular but similar
marks between the elliptic ornaments.
The successive steps in the
shading of the ball-and-socket
ocelli can be followed out with
equal clearness. The brown, orange,
and pale-leadened narrow zones,
which border the lower black
mark of the elliptic ornament,
can be seen gradually to become
more and more softened and shaded
into each other, with the upper
lighter part towards the left-hand
corner rendered still lighter,
so as to become almost white,
and at the same time more contracted.
But even in the most perfect
ball-and-socket ocelli a slight
difference in the tints, though
not in the shading, between the
upper and lower parts of the
ball can be perceived, as before
noticed; and the line of separation
is oblique, in the same direction
as the bright coloured shades
of the elliptic ornaments. Thus
almost every minute detail in
the shape and colouring of the
ball-and-socket ocelli can be
shewn to follow from gradual
changes in the elliptic ornaments;
and the development of the latter
can be traced by equally small
steps from the union of two almost
simple spots, the lower one (see
fig. 58) having some dull fulvous
shading on its upper side.
The extremities of the longer
secondary feathers which bear
the perfect ball-and-socket ocelli,
are peculiarly ornamented (see
fig. 61). The oblique longitudinal
stripes suddenly cease upwards
and become confused; and above
this limit the whole upper end
of the feather (a) is covered
with white dots, surrounded by
little black rings, standing
on a dark ground. The oblique
stripe belonging to the uppermost
ocellus (b) is barely represented
by a very short irregular black
mark with the usual, curved,
transverse base. As this stripe
is thus abruptly cut off, we
can perhaps understand from what
has gone before, how it is that
the upper thickened part of the
ring is here absent; for, as
before stated, this thickened
part apparently stands in some
relation with a broken prolongation
from the next higher spot. From
the absence of the upper and
thickened part of the ring, the
uppermost ocellus, though perfect
in all other respects, appears
as if its top had been obliquely
sliced off. It would, I think,
perplex any one, who believes
that the plumage of the Argus
pheasant was created as we now
see it, to account for the imperfect
condition of the uppermost ocellus.
I should add that on the secondary
wing-feather farthest from the
body all the ocelli are smaller
and less perfect than on the
other feathers, and have the
upper part of the ring deficient,
as in the case just mentioned.
The imperfection here seems to
be connected with the fact that
the spots on this feather shew
less tendency than usual to become
confluent into stripes; they
are, on the contrary, often broken
up into smaller spots, so that
two or three rows run down to
the same ocellus.
There still remains another
very curious point, first observed
by Mr. T. W. Wood,* which deserves
attention. In a photograph, given
me by Mr. Ward, of a specimen
mounted as in the act of display,
it may be seen that on the feathers
which are held perpendicularly,
the white marks on the ocelli,
representing light reflected
from a convex surface, are at
the upper or further end, that
is, are directed upwards; and
the bird whilst displaying himself
on the ground would naturally
be illuminated from above. But
here comes the curious point;
the outer feathers are held almost
horizontally, and their ocelli
ought likewise to appear as if
illuminated from above, and consequently
the white marks ought to be placed
on the upper sides of the ocelli;
and, wonderful as is the fact,
they are thus placed! Hence the
ocelli on the several feathers,
though occupying very different
positions with respect to the
light, all appear as if illuminated
from above, just as an artist
would have shaded them. Nevertheless
they are not illuminated from
strictly the same point as they
ought to be; for the white marks
on the ocelli of the feathers
which are held almost horizontally,
are placed rather too much towards
the further end; that is, they
are not sufficiently lateral.
We have, however, no right to
expect absolute perfection in
a part rendered ornamental through
sexual selection, any more than
we have in a part modified through
natural selection for real use;
for instance, in that wondrous
organ the human eye. And we know
what Helmholtz, the highest authority
in Europe on the subject, has
said about the human eye; that
if an optician had sold him an
instrument so carelessly made,
he would have thought himself
fully justified in returning
it.*(2)
* The Field, May 28, 1870.
*(2) Popular Lectures on Scientific
Subjects, Eng. trans., 1873,
pp. 219, 227, 269, 390.
We have now seen that a perfect
series can be followed, from
simple spots to the wonderful
ball-and-socket ornaments. Mr.
Gould, who kindly gave me some
of these feathers, fully agrees
with me in the completeness of
the gradation. It is obvious
that the stages in development
exhibited by the feathers on
the same bird do not at all necessarily
shew us the steps passed through
by the extinct progenitors of
the species; but they probably
give us the clue to the actual
steps, and they at least prove
to demonstration that a gradation
is possible. Bearing in mind
how carefully the male Argus
pheasant displays his plumes
before the female, as well as
the many facts rendering it probable
that female birds prefer the
more attractive males, no one
who admits the agency of sexual
selection in any case will deny
that a simple dark spot with
some fulvous shading might be
converted, through the approximation
and modification of two adjoining
spots, together with some slight
increase of colour, into one
of the so-called elliptic ornaments.
These latter ornaments have been
shewn to many persons, and all
have admitted that they are beautiful,
some thinking them even more
so than the ball-and-socket ocelli.
As the secondary plumes became
lengthened through sexual selection,
and as the elliptic ornaments
increased in diameter, their
colours apparently became less
bright; and then the ornamentation
of the plumes had to be gained
by an improvement in the pattern
and shading; and this process
was carried on until the wonderful
ball-and-socket ocelli were finally
developed. Thus we can understand-
and in no other way as it seems
to me- the present condition
and origin of the ornaments on
the wing-feathers of the Argus
pheasant.
From the light afforded by the
principle of gradation- from
what we know of the laws of variation-
from the changes which have taken
place in many of our domesticated
birds- and, lastly, from the
character (as we shall hereafter
see more clearly) of the immature
plumage of young birds- we can
sometimes indicate, with a certain
amount of confidence, the probable
steps by which the males have
acquired their brilliant plumage
and various ornaments; yet in
many cases we are involved in
complete darkness. Mr. Gould
several years ago pointed out
to me a humming-bird, the Urosticte
benjamini, remarkable for the
curious differences between the
sexes. The male, besides a splendid
gorget, has greenish-black tail-feathers,
with the four central ones tipped
with white; in the female, as
with most of the allied species,
the three outer tail-feathers
on each side are tipped with
white, so that the male has the
four central, whilst the female
has the six exterior feathers
ornamented with white tips. What
makes the case more curious is
that, although the colouring
of the tail differs remarkably
in both sexes of many kinds of
humming-birds, Mr. Gould does
not know a single species, besides
the Urosticte, in which the male
has the four central feathers
tipped with white.
The Duke of
Argyll, in commenting on this
case,* passes over sexual
selection, and asks, "What explanation
does the law of natural selection
give of such specific varieties
as these?" He answers "none whatever";
and I quite agree with him. But
can this be so confidently said
of sexual selection? Seeing in
how many ways the tail-feathers
of humming-birds differ, why
should not the four central feathers
have varied in this one species
alone, so as to have acquired
white tips? The variations may
have been gradual, or somewhat
abrupt as in the case recently
given of the humming-birds near
Bogota, in which certain individuals
alone have the "central tail-feathers
tipped with beautiful green." In
the female of the Urosticte I
noticed extremely minute or rudimental
white tips to the two outer of
the four central black tail-feathers;
so that here we have an indication
of change of some kind in the
plumage of this species. If we
grant the possibility of the
central tail-feathers of the
male varying in whiteness, there
is nothing strange in such variations
having been sexually selected.
The white tips, together with
the small white ear-tufts, certainly
add, as the Duke of Argyll admits,
to the beauty of the male; and
whiteness is apparently appreciated
by other birds, as may be inferred
from such cases as the snow-white
male of the bell-bird. The statement
made by Sir R. Heron should not
be forgotten, namely, that his
peahens, when debarred from access
to the pied peacock, would not
unite with any other male, and
during that season produced no
offspring. Nor is it strange
that variations in the tail-feathers
of the Urosticte should have
been specially selected for the
sake of ornament, for the next
succeeding genus in the family
takes its name of Metallura from
the splendour of these feathers.
We have, moreover, good evidence
that humming-birds take especial
pains in displaying their tail-feathers;
Mr. Belt,*(2) after describing
the beauty of the Florisuga mellivora,
says, "I have seen the female
sitting on a branch, and two
males displaying their charms
in front of her. One would shoot
up like a rocket, then suddenly
expanding the snow-white tail,
like an inverted parachute, slowly
descend in front of her, turning
round gradually to shew off back
and front.... The expanded white
tail covered more space than
all the rest of the bird, and
was evidently the grand feature
in the performance. Whilst one
male was descending, the other
would shoot up and come slowly
down expanded. The entertainment
would end in a fight between
the two performers; but whether
the most beautiful or the most
pugnacious was the accepted suitor,
I know not." Mr. Gould, after
describing the peculiar plumage
of the Urosticte, adds, "that
ornament and variety is the sole
object, I have myself but little
doubt."*(3) If this be admitted,
we can perceive that the males
which during former times were
decked in the most elegant and
novel manner would have gained
an advantage, not in the ordinary
struggle for life, but in rivalry
with other males, and would have
left a larger number of offspring
to inherit their newly-acquired
beauty.
* The Reign of Law, 1867, p.
247.
*(2) The Naturalist in Nicaragua,
1874, p. 112.
*(3) Introduction to the Trochilidae,
1861, p. 110. |