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of the locality, the same species building a quite different nest, as
respects warmth and stability, in the colder portions of its habitat
from that which it constructs in the warmer portions.

But while these deviations under diverse circumstances readily
explain variation in. the situation and character of the nests of the
same species, they &il to explain why closely allied species, living
together under precisely the same conditions of environmient, and
sometimes so closely resembling each other in size, color, and all
external characters as to require the eye of an expert to detect their
specific diversity, should build totally unlike nests, and display
almost the widest possible differences in respect to their situation.
To cite, in illustration, a single example from the many that might
be given, we may instance our common Pewees and Flycatchers.
In this small group we find a wide range of diversity in breeding
habits among species most intimately related in structure and gen-
eral habits. The Least Pewee builds a small, compact, felted nest
of fine soft materials, and its nearest allies, the Acadian and Traill's,
build &r ruder and much more bulky structures of coarse grasses,
strips of bark, and other similar materials. Another near relative of
these species, the Wood Pewee, selects for its nesting-site a lichen-
covered dead branch, on which to saddle its small, highly artistic,
cup-shaped nest, covered externally with lichens glued to the surface
in such a manner as to render the structure almost indistinguish-
able from a natural protuberance of the branch itself. The Bridge
Pewee, another allied species, builds a large bulky nest, formed
outwardly of a heavy layer of mud, copiously lined with dry grass
and feathers, and shelters it in the chinks of walls, under shelv-
ing rocks, in sheds, outbuildings, and under bridges. The Great-
crested Flycatcher chooses hollow trees or deserted Woodpeckers'
holes in which to form its nest and deposit its eggs, while its allies,
the Kingbirds (genus Tyrannus)^ build large open nests, which they
make no attempt to conceal.

Notwithstanding all this diversity of situation and structure
among closely allied species, birds' nests have been divided into
two classes, according to *' whether the contents (eggs, young, or '
sitting bird) are hidden or exposed to view," and the broad general-
ization based thereon that the character of the nest is intimately
related to the color of the female parent-bird. This, in fact, is Mr.



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26 Allen on an Inadequate ''Theory of Birdi NesisT

Wallace's " Theory of Birds' Nests." ♦ This "theory" has for its
basis the assumed '' law which connects the colors of female birds
with the mode of nidification." Mr. Wallace states it to be a rule,
open to ** but few exceptions," " that when both sexes are of strik-
ingly gay and conspicuous colors, the nest is ... . such as to conceal
the sitting bird ; while, whenever there is a striking contrast of colors,
the male being gay and conspicuous and the female dull and ob-
scure, the nest is open and the sitting bird exposed to view." He
cites as examples of the first class, or those in which the female is
conspicuously colored and the nest concealed or 'covered, '*six im-
portant families of Fiesiroetres, four of Scafuores, the PdUaci^ and sev-
eral genera and three entire families of Passerea, comprising about
twelve hundred species, or about one seventh of all known birds."
This statement, however, proves on examination to be quite too
sweeping, since a large proportion of the species here named either
do not have a concealed nest» or are of sombre and obscure tints.
There are also other entire families and various additional genera,
in which the males are brilliantly and the females obscurely colored,
which build a domed nest. I now propose, so far as the limits of a
short article will allow, to test this theory by a rapid survey of the
birds of North America, — an area certainly lai^e enough to afford
a fair basis of judgment. For this purpose I shall consider the
modes of nidification under four heads, namely, (1) nidification in
holes in trees ; (2) in burrows ; (3) domed, pensile, or otherwise
more or less " covered " nests ; and (4) nests wholly open.

1. Among North American birds those that habitually nest in
holes in trees embrace several species of the smaller Owls, one or
two kinds of small Hawks, all the various species of Woodpeckers^
all the numerous species of Titmice of the genera Laphophanee and
ParuSf the several species of Nuthatches, the Brown Creeper, some
of the Wrens, the Bluebirds (three species of Sialia), several species
of Swallows, Martins, and Swifts, the Great-crested Flycatcher, the
Carolina Paroquet, and three or four species of Ducks. In very few
of these can the colors be considered as " strikingly gay and con-
spicuous," and when this is the case, as in the Bluebirds, a few of

♦ Originally published in the Intellectual Observer of July, 1867, and repub-
lished with additions in 1870 in a collection of essays entiUed " Contributions
to the Theory of Natural Selection," and alluded to in more recent articles
by the same author, including hia recent paper on '' The Colors of Animak and
Plants."



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Allbn on an Inadequate '* Theory of Birds' Nests." 27

the Woodpeckers, some of the SwallowB, the Wood-Duck, the Hooded
Merganser and the Buffle-head, the females are much paler and duller
colored than the males. In many other mst^ces the colors are in the
highest degree adapted for concealment under every circumstance,
and especially in a sitting fen\ale bird, as, for instance, in the Brown
Creeper, the Wrens, some of the Titmice, the Swifts, and various
others.*

2. The burrowing species embrace 'the Prairie Owl, the King-
fishers, two species of Sand Martin or Bank Swallow, the Petrels,
various species of Auks and Puffins, and some of the Guillemots.
The Kingfishers possibly excepted, almost none of these have bright
or conspicuous colors, while in several the colors could scarcely be
better adapted for concealment Especially is this the case with the
Owl and Sand Martins, with their dull neutral tints.

3. Among the comparatively few species that build a covered
or domed nest are the ground-building Golden-crowned Wagtail or
"Oven-Bird," the Dipper or Water-Ousel, the Meadow Lark, the
common Qiiail, and several Warblers. The first two of these have
tints peculiarly adapted for concealment, and the Colors of the dorsal
area in the others are likewise " protective.'' Among the species
building covered nests in reeds, bushes, or low trees, are Marsh
Wrens, some of the other Wrens, the smaller Tits (genera PsaUrv-
parus, AuriparuSy eta), several of the Warblers (family Sylvicolidcs),
the Magpie, and perhaps a very few others. Of these the Wrens and
Tits are all obscurely or protectively colored, and have no '* surpris-
ingly g&y cmd conspicuous " tints. Some of the Warblers are more
brightly colored, and a few have rather conspicuous markings ; but
these features are almost wholly confined to the male, the females
being of comparatively dull and obscure tints. The Magpie has
showy colors and a very long tail, and the bulky nest, wholly con-
cealing the sitting bird, may be useful in hiding these otherwise be-
traying features. The species which build hanging, purse-shaped, or
snbpensile nests are the Orioles and Vireos. In the case of the
former the nest is most illy adapted for protection from the most
dangerous foes of the species, the predatory Crows, Jays, and
Cuckoos, being often a conspicuous object, with, so far as the
United States species are concerned, no compensating feature of
security. Here again, while the males are in some instances arrayed
in " strikingly gay and conspicuous colors," the females do not to
any great extent share their bright hues, the sexual differences in



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28 Allen an an Inadequate "Theory of Birds' Jietts.**

color among our native birds being rarely greater than in these
species. The subpensile nests of some of the Vireos are to be per-
haps more properly referred to the type of open nests. In either
case we find only slight sexual difference in color, with the olivaceous
hue of the back well fitted for concealing the female bird. But this
is in part offset by the usually light color and somewhat exposed
situation of the nest.

4. The great bulk of the species fall of course into the fourth
category, or those with tho nest open. These embrace (with two
exceptions, the Woodpeckers and the Kingfishers) birds of every
family represented in our fauna, and are about equally divided be-
tween ground-builders and those which nest in bushes or trees. As
a rule (as, in fact, throughout the class of birds) in those arrayed in
conspicuous tints the females are obscurely colored, in comparison
with the males. Yet to this rule there are exceptions, as notably
among the Jays, some of which do have '* surprisingly gay and con-
spicuous colors," and among which both sexes are equally brilliant.
The shining black color of the Crows, the Raven, and some of the
Blackbirds are equally or (in the latter) almost equally shared by
both sexes, while the color is by no means well adapted to conceal-
ment. In many species the males, even when brightly colored,
share with the females the duties of incubation. This is the case
with the Rose-breasted Grosbeak, in which the male is most con-
spicuously colored, and who not only shares the labor of incubation,
but has the most injudicious habit of indulging in loud song while
sitting on the nest In many of our ground-nesting Sparrows the
sexes, in respect to coloration, are wholly indistinguishable ; their
obscure colors, arranged generally in streaks and spots, are cer-
tainly in the highest degree protective ; .their nests, although not
domed, or even " covered," in the strict sense of the term, are gen-
erally most effectually concealed under tufts of herbage, and are
hence far better shielded from observation than the pensile, domed,
or bulky, covered nests that are regarded by our author as so highly
conducive to security through the concealment of the eggs and
young or the sitting female.

Among the groups instanced by Mr. Wallace as building open
nests are "the extensive families of the Warblers (Sylviadce),
Thrushes {Turdidoe), Flycatchers (MtueicapidcB), and Shrikes (Xo-
niadce)J* While in a considerable proportion of the species of
these groups the males are " beautifully marked with gay and con-



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Allen an an Inadequate ''Theory of Birds* Nests." 29

spiouous tintfly'* ** in every ease the females are less gay, and are most
frequently of the very plainest and least conspicuous hues. Now/'
he continues^ " throughout the whole of tliese families the nest is
^pen^* and 1 am not aware of a single instance in which any one of
these birds builds a domed nesty or places it in a hole of a tree^ or
under ground^ or in any place where it is eflTectually concealed." As
regards the North American representatives of these groups, there
are frequent exceptions to this rule, as I have already shown, and
that Mr. Wallace did not know of exceptions only shows that his
examination of the subject must have been very superficial As
further evidence of the imperfection and inexactness of Mr. Wal-
lace's knowledge of the subject concerning which he theorizes so
boldly and speaks so emphatically, may be cited his remark about
the IcteridcBy or " Hangnests." " The red or yellow and black plu-
mage of most of these birds," he says, " is very conspicuous, and
is exactly alike in both sexes. They are celebrated for their fine
purse-shaped pensile nests." As regards the facts of the case, there
is no family of Passerine birds where the s^xes, as a rule, are more
widely different, the difference affecting not merely color, but also
size, the females being not only much duller colored than the males,
but much smaller. The instances in which both sexes are equally
brilliant are the exceptions.

To summarize the foregoing remarks, it has been shown, so far
as the birds of North America are concerned (and the same could
easily be shown for other equally extensive regions), that the spe-
cies which breed in holes in trees, in burrows in the ground, or in
domed, pensile, or covered nests, are as often dull, obscurely col-
ored species as bright-colored ; that when the species are conspicu-
ously colored, it is generally only the male that is attired in strik-
ingly gAy tints, the females having comparatively dull colors ; and
that often species in which both sexes are clothed in bright and
equally conspicuous tints build an open nest ; while the " theory "
demands just the opposite of these conditions. In other words,
that birds nest in holes, in open or in covered nests, without regard
to whether the female is brightly or obscurely colored. Furthermore,
that pensile and bulky covered nests are far more open to discovery
than ordinary open nests, so that the advantage of having the con-
tents concealed, be it eggs, young, or the female parent, is more

* The italicized portions are as in the original



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30 Allen on an Inadequate "Theory of Birds' NesUy

than counterbalanced bj the readiness with which the nest itMlf
is discovered.

Not to do Mr. Wallace or his theory injustice, it maj be added
that he has instanced a considerable number of lai^ families of
birds, found outside of North America, in which the species nest in
hoUow trees, and in which both sexes do have *' surprisingly gay
and conspicuous colors." Among these are the Trogons, the Barbets,
the Puff-birds, the Toucans, and the great group of Parrots and
Paroquets. But Mr. Wallace has himself given an apparently far
better reason for this method of nidification in some of these groups
than that involved in his above-given theory, namely, that they have
not the necessary *' tools ^ for the construction of an elaborate nest.
Most of them are weak-footed and sedentary, whUe in other cases
the form of the bill renders the construction of a nest almost im-
possible. Another large group, the species of which nest in holes
in trees, are the Woodpeckers. Here an obvious and far more
rational explanation is apparent than that afforded by the theory of
concealment, for here the scores of dull-plumaged, sombre-colored
species nest in holes just as do those that are conspicuously at-
tired. In this group the species do not seek cavities already at hand,
as is the case in some of the groups just cited, but form them them-
selves, and use them not only for purposes of nidification, but often
more or less habitually as places of shelter. Nothing seems more
natural than that they should avail themselves in this way of the
advantages afforded them by their powerful chisel-shaped beaks,
which they are constantly using as an abrading or " digging " organ
in their search for food. The same explanation holds equally good
for the plainly colored Tits that nidificate in holes that they them-
selves have the power of forming.

The Auks, Puffins, and some of the Guillemots are among the
species I have cited as breeding in burrows. As they are species
(occasionally conspicuous markings about the biU or head excepted)
of neutral or obscure tints, — particularly as respects the exposed
dorsal area of the sitting female, — their resorting to burrows is
hardly necessary for concealment, since these species have no
'^ strikingly gay " attire of plumage that would render the sitting
bird in any case conspicuous. Such resorts, however, prove to be
to them a great source of security, and give them an immense ad-
vantage over other species of the same family that breed at the
same localities with them, but in a wholly exposed manner. The



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Allen on an Inadequate "Theory of Birdd Nests'' 31

chief enemj of these birds is man, bj whom they are robbed of
their eggs in a most brutal and wholesale way. The species that
breed in deep crevices in the rocks almost wholly escape the rapacity
of their human foes, the eggs being almost invariably, it is said,
placed beyond reach, while those (some of the Guillemots) that de-
posit their eggs on the surface are robbed almost to extermination.
The dull, thoroughly protective colors of the Burrowing Owls, of
which there are several species, render them often difficult objects
to discover even when wholly exposed, yet they nidificate in de-
serted marmot holes, and there find security against the attacks of
predatory skunks and foxes, to which they would be exposed if nest-
ing on the ground, — usually the only other alternative in the
localities they inhabit. In fact, instances might be multiplied in
which the breeding of birds in holes in trees, or in the earth, or in
otherwise concealed nests, might be explained more rationally than
by the theory of concealment of a brightly colored female parent, —
the basis of Mr. Wallace's ingenious "Theory of Birds* Nests," —
namely, security from enemies through other means than simply
concealment.

Mr. Wallace, in commenting on ** What the Facts Teach us " in
relation to this theory, argues that the differences in color between
the sexes in birds that build an open nest may have been brought
about by the bright-colored females being weeded out or eliminated
in consequence of being more exposed to the attacks of enemies,
since any n^odification of color which rendered them more conspic-
uous would lead to their destruction and that of their offspring;
while the attainment of inconspicuous tints would tend to their
preservation. Hence this theory is intimately connected with, or
in part based upon, Mr. Darwin^s theory of "sexual selection,"
which Mr. Wallace at this time accepted, but which he has recently
had the better judgment to discard as an inadequate explanation of
sexual differences in color among animals.

The most surprising thing about Mr. Wallace's " Theory of Birds'
Nests"* is its inadequacy, and its irrelevancy to the facts it was
proposed to explain, and in this respect it is scarcely excelled by any
of the crude inventions into whicH the more ardent supporters of the

* I wish to here state explicitly that I refer in these remarks wholly to Mr.
Wallace's "Theory of Birds* Nests,", and not to his most admirable essay on
"The Philosophy of Birds' Nests," which is replete with soond sense, and to
nearly every syllable of which I most heartily subscribe.



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32 Goss an Breeding of the Duck Hawk.

theory of evolution by means of what haa been termed ''natund
selection " and " sexual selection " have been betrayed.

In conclusion, I desire to call attention to an interesting coinci-
dence between the manner of nesting among birds and the color of
the eggs, and one so striking that it is almost surprising that some
ingenious theorist has not seized upon it as a basis for a " theory of
birds' nests," either independently or as a modification of that pro-
posed by Mr. Wallace. It curiously happens that nearly all birds
that nest in holes, either in the ground or in trees, lay taktte egg$,
embracing, for instance, all the Woodpeckers, Kingfishers, Bee-eat-
ers, Rollers, Horubills, Barbets, Pufi^-Birds, Trogons, Toucans, Par-
rots, Paroquets, and Swifts, while only occasionally are the eggs
white in species which build an open nest. In only two or three
groups of land birds, co-ordinate with those just named, that build
an open nest, are the eggs white, namely, the Owls, Humming-Birds,
and Pigeons. On the other hand, in only two or three small groups
of species that nidificate in holes are the eggs speckled or in any
way colored. There is, in fact, a closer relationship, or rather a
more uniform correlation, between the color of the eggs and the
manner of nesting than between the color of the female parent and
the concealment or exposure of the nest. There are, however, here
apparently too many exceptions to bring this coincidence into the
relation of cause and efiect. It is perhaps rather comparable with
the pattern of coloration that so often, to a greater or less degree,
marks nearly all the species of a whole natural family, and often
prevails throughout large genera, for which the conditions of envi-
ronment offer no explanation, since it as often occurs in cosmopoli-
tan groups as in those of local distribution, and which, in the pres-
ent state of our knowledge, seems wholly inexplicable.



BREEDING OF THE DUCK HAWK IN TREES.

BY N. S. Goas.

As the Falco communis var. anatum is supposed to nest almost
exclusively on high rocky cliffs, and rarely if ever in other situa-
tions, I think it will be of interest for me to say that I found
in February, 1875, a pair nesting about three miles southeast of
Neosho Falls, Kansas, in the timber on the banks of the Neosho



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Goss an Breeding of the Duck Hawk. 33

River. The nest was in a large sycamore, about fifty feet from the
ground^ in a trough-like cavity formed by the breaking off of a hol-
low limb near the body of the tree. I watched the pair closely,
with the view of securing both the birds and their eggs. March 27
I became satisfied that the birds were sitting, and I shot the female,
but was unable to get near enough to shoot the male. The next
morning I hired a young man to climb the tree, who found three
fresh eggs, laid on the fine soft rotten wood in a hollow worked out
of the same to fit the body. There was no other material or lining,
except a few feathers and down mixed with the decayed wood.

The ground-color of the eggs is grayish-ochre, spotted and
blotched with dark reddish-brown, the blotches running together
towards the largo end, where they are^ a shade darker. Length,
respectively, 2.20, 2.30, and 2.40 ; diameter of each, 1.70 inches.

March 17, 1876, I found a pair nesting on the opposite side of
the river from the above-described nest, in. a Cottonwood, at least
sixty feet from the ground, the birds entering a knot-hole in the
tree, apparently not over five or six inches in diameter. The tree
was very straight, and without limbs to the nest, and consequently
out of reach. The birds were very- noisy, but shy. I wounded
both the birds, but failed to get them.

February 2, 1877, I noticed a pair flying into the same tree.
April 9, I shot them both. I now have the three birds in my col-
lection. The measurements, as taken from the birds when shot,
are as follows : —

Sex. Length. Stretch of Wing. Wing. TaiL Tanoa. BiU.

March 27, 1875.... ? 20.00 46.00 15.00 7.60 1.85 .96

April9, 1877...... 9 19-75 45.50 14.76 7.50 1.85 .96

April9,1877 S 18.00 41.00 18.60 6.50 1.80 .90

Cere, .81.

For a description of the species see " North American Birds,*' by
Baird, Brewer, and Ridgway (Vol. 111. p. 128). I will, add : Iris,
brown ; bill, horn-blue, with the base pale green ; cere and eyelidsi
greenish-yellow ; legs and feet, lemon-yellow ; claws, black.

April 30, 1877, I found a pair about four miles farther up the
river, breeding in a hollow broken limb of a giant sycamore. Frpm
the actions of the birds, I think they had young. I feel confident
they will nest there next season, and, if so, shall try very hard to
procure the eggs.

The birds are very noisy while mating, but silent during incuba-
tion. The males, so far as noticed, sit upon the eggs in the fore part



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34 Becent LitercUure.

of the daj, the females during the latter part of the daj, each, whUe
off duty, occaaioDally feeding the other, but putting in a good riiare
of the time as sentinels, perched upon a favorite dead limb near the
nest, ready to give the alarm in case of approaching danger. At
such times thej scold rapidly, and manifest great anxiety and fear,
circling overhead, occasionally alighting, and taking good care to
keep out of reach. The fear of man is not without cause, for our
hunters never lose an opportunity to shoot at them, knowijig how
destructive they are to the water-fowls found in the sloughs along
the river-bottoms.

, Keoeho Falls, Kansas,



Birds of the Vicinity of Cincinnati. — Mr. F. W. Langdon's
Catalogue of the Birds of the Yicinity of Cincinnati,* embraces two hun-
dred and seventy-nine species, about one third of which are marked as
known to breed in the vicinity. The author gives notes respecting the
times of migration, relative abundance, etc., of each species, and dis-
tinguishes those recorded in the list simply from their known range in-



Online LibraryNuttall Ornithological ClubBulletin of the Nuttall Ornithological Club: a quarterly jjournal of ornithology → online text (page 29 of 50)