The evolution of bird-song, with observations on the influence of heredity and limitation; online

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THE EVOLUTION OF BIRD-SONG



THE

EVOLUTION OF BIRD-SONG



OBSERVATIONS ON THE INFLUENCE OF
HEREDITY AND IMITATION



CHARLES A. WITCHELL

AUTHOR OF 'THE FAUNA OF GLOUCESTERSHIRE'



LONDON

ADAM AND CHARLES BLACK
1896



PREFACE

I WISH to mention in this place my deep sense of
obligation to those kind helpers who have given
me notes on the subjects discussed in this book.
I wish also to acknowledge my gratitude to the late
Professor Harker, F.L.S., whose lamented death
recently occurred. He, from the first, encouraged
me to continue my observation of bird-song ; and,
in 1890, he devoted a considerable amount of time
to harmoniously arranging the results of my in-
vestigations.

When I state that Mr. J. E. Harting generously
offered to look over the proof-sheets of this work
(which offer was, of course, gladly accepted), the
public will appreciate the extent of my indebtedness
to an author and editor so accomplished. The first



EVOLUTION OF BIRD- SONG



3 2 pages had then been returned to the printer ;
but, in revising the remainder, I continually per-
ceived the great advantages derived from Mr.
Harting's perusal.

However novel or otherwise may be the theories
stated in this book, I can at least claim that, so far
as I am concerned, they are absolutely original, all
of them having been committed to writing, though,
in some instances, not under their present titles,
before I consulted any person, or any book, in regard
to them.

CHARLES A. WITCHELL.

LONDON, April 1896.



CONTENTS



INTRODUCTION ... . . . i-n

CHAPTER I

THE ORIGIN OF THE VOICE

Darwin's opinion that the voice resulted from involuntary move-
ments of muscles Combat the chief occasion for such move-
ments Prevalence of a puff or hiss as a menace Accidental
cries of newts . . . , ' . 12-21

CHAPTER II

ALARM-NOTES

Combat-cry serviceable as an alarm Repetition of single alarm-
cries, in terror Theory of evolution of certain rattling cries
by such repetitions Discrimination of enemies evidenced by
cries and deportment Inherited knowledge of alarm-cries 22-32

CHAPTER III

THE INFLUENCE OF COMBAT

Rivalry and emulation Among polygamous species, selection
dependent on combat The snapping of bill as a menace
Chaffinch's war-note Singing during combat . . 33-40



EVOLUTION OF BIRD- SONG



CHAPTER IV

THE CALL-NOTE

PAGES

Erroneous descriptions of call-notes Chaffinch's cry pink not
a call-note Distress-cries of young are of use as call-notes
when the birds leave the nest Influence of gregariousness
and of fear Absence of call-notes from the songs of extrava-
gant singers : prevalence of them in songs of inferior singers 41-48



CHAPTER V

THE SIMPLEST SONGS

Repetition of call-notes in the breeding season Construction of
strains by this method Examples Call-notes concluding
spring songs of skylark Movements of wings during song
Repetition of same intervals of pitch . . . 49-58

CHAPTER VI

NOTICEABLE INCIDENTS CONNECTED WITH BIRD-SONG

Songs are generally uttered by males : exceptions Not until birds
have attained full size: exceptions Most frequently at
morning and evening : influence of weather Tendency to
rise in pitch with vehemence Only small birds properly
sing Singers arboreal birds generally Effect of living amid
foliage : on size, hearing, and voice Accent in songs
Singers clad in sober hues Development of the eyes in
detecting danger Necessity of leisure Labours of parent-
birds Laborious and stealthy birds habitually poor in song
Flight in song : for purposes of display Fluttering of wings
a means of address Ventriloquism Singing in chorus . 59-85



CONTENTS



CHAPTER VII

THE INFLUENCE OF HEREDITY IN THE PERPETUATION OF
THE CRIES OF BIRDS

PAGES

Absolute inheritance of cries in plovers, common fowl, duck, swan,
pheasant, etc. Family cries Cries of allied young more
alike than those of allied adults The cahs of the crows :
heard in starling and jay Similarity between starling and
thrushes Rattling alarm of mistle-thrush, modified in black-
bird, ousel, song -thrush, fieldfare, and American robin
Similarity of occasions of utterance of alarms by blackbird and
European robin Similarities traced in call-notes of birds of
the thrush family : also between their songs Prevalence of
imitation The warblers Particular cry common to nightin-
gale, willow-warbler, and chiffchaff Similar alarm-croaks of
nightingale, sedge- warbler, and lesser whitethroat Recapitu-
lation Similarities between notes of wagtails Songs of tree-
pipit and meadow-pipit described : similarity to that of sky-
lark Larks of three continents, with the same manner of
song Family resemblances in the buntings Resemblance
between call -notes of yellow bunting and greenfinch in
flight Notes of the finches Canary has family traits Tell
tell cries of house -sparrow and greenfinch Similar cries
of young chaffinch and young house-sparrow Various other
orders mentioned . . . . . .86-139



CHAPTER VIII

VARIATION IN BIRD-VOICES : ITS CAUSES AND EFFECTS

Prevalence of variation Instances mentioned by authors
Variation in songs of blackbird, yellow-hammer, chaffinch,
robin, house-sparrow, and cuckoo Illustrated in the robin's
alarm . . ... . . 140-158



EVOLUTION OF BIRD- SONG



CHAPTER IX

THE INFLUENCE OF IMITATION IN RELATION TO BIRD-SONG

PAGES

Imitation by dogs and other animals The notes of some birds
wholly perpetuated by imitation ; of others wholly by inherit-
ance Observations of authors on the mimicry of birds
House-sparrow with lark's song, and other instances Pos-
sible effects of imitation Interesting similarities observable :
between notes of birds and sounds produced by elements the
music of the streams by insects, by quadrupeds, by birds
General observations Chief subjects imitated by various
birds thrushes, robins, skylarks, sedge - warblers showed
influence of arrival of summer migrants Full records of
songs of thrush, robin, skylark, starling, sedge -warbler,
redstart, nightingale, marsh-warbler, wheatear, goldcrest,
whitethroats, nuthatch, reed - bunting, stonechat, blackbird,
chaffinch, and others ..... 159-229

CHAPTER X

THE MUSIC OF BIRD-SONG

Repetition of intervals of pitch Our diatonic scale was known
3000 years ago Curious intervals sung by great titmouse,
chaffinch, and robin Curious crowing of fowls Intervals in
blackbirds' alarms Music of the blackcap, mistle-thrush, and
American robin ...... 230-238

CONCLUSION ...... 239-240

APPENDIX

Transcripts of music sung by blackbirds, thrushes, and skylarks 241-246

BIBLIOGRAPHY OF THE SUBJECT . . . 247, 248

INDEX .... . 249-253



INTRODUCTION

THE idea of making a scientific investigation of the
various features of bird-song first occurred to me in
the year 1881, on the occasion of my listening to a
nightingale near Stroud. I observed the frequent
utterance of a little slurred whistle at the com-
mencement of many of its songs a whistle which
I knew to be uttered by several of its congeners ;
and the songs themselves often seemed to include
a repetition of the notes of birds of other genera
with which I was acquainted. I had never read
anything particular about the songs of birds, but
was aware of the imitativeness of many musical
species when in captivity, and I was acquainted
with the notes of most of the wild birds found in
Gloucestershire. I listened to this nightingale, at
the distance of a few yards, on eighteen out of the
twenty-one evenings on which he sang. His nest



EVOLUTION OF BIRD- SONG



having been robbed, he afterwards uttered only one
or two dismal notes at long intervals. I knew the
song of this bird very well ; and afterwards, in the
same season, when listening to other nightingales, I
soon learned the well-known fact that these birds,
like many others, differ individually in their songs
and times of singing. During the next few years
I found no inducement to attempt any deliberate
investigation of the songs of birds; but in 1885
the subject was again brought prominently before
me. A thrush of very remarkable vocal powers
had its nest in our garden, and sang every day in
a high acacia-tree not far from the house. At that
time I was much at home nursing a sick relation,
and in these circumstances the loud clear song of
the thrush was particularly noticeable. Towards
the end of May we observed that on every success-
ive morning the bird began to sing about a minute
and a half earlier, so that we could predict almost
to a minute the time when his first notes would be
heard. His extraordinary endurance led me to
record his periods of song, with the astounding
result that these on one day amounted to an
aggregate of no less than sixteen hours, thus
allowing only three hours of silence during the
whole time of song, which extended from 2.45



INTR OD UCTION



A.M. to 9.30 P.M. This thrush was the first wild
one which I heard imitate. Like other persons
fond of the country, I had listened to hundreds,
perhaps thousands, of thrushes, and yet had never
noticed their mimicry. The bird in question exactly
reproduced the "call" of the partridge I mean
the cry heard so often on winter evenings and
this was the sound which first directed my atten-
tion critically to the character of the song. The
thrush also repeated many cries then well known
to me ; for instance, the most prominent notes of
the house -spar row, greenfinch, and chaffinch ; the
loud, prolonged call of the blue titmouse ; and notes
of the wagtail, brown wren, and some other birds.
The invalid, a brother who had been my frequent
companion in the country, fully endorsed my
opinion of certain notes of the singer ; indeed,
he was the first to identify its imitation of the
brown linnet.

Having found mimicry in the thrush, I listened
for it in the songs of other birds. In some, such
as those of the hedge -accentor, tree -pipit, brown
wren, chaffinch, and greenfinch, no trace of it was
found, though the birds sang well ; but in others,
and especially in those of the starling, sedge-
warbler, redstart, blackbird, skylark, and robin,



EVOLUTION OF BIRD- SONG



more or less imitation was apparent About two
years later I began to make extensive records of
the imitations sung by wild birds, my method being
to identify the singer, and then to write down the
date and place of singing, the state of the weather,
number of times of singing per minute, and the
particular sounds which appeared to be reproduced.
Some of the sounds imitated were rendered with
wonderful fidelity by the better mimics, such as the
sedge - warbler, starling, and thrush ; other birds,
with full-toned voices, as the robin, blackbird, and
nightingale, appeared to be able to repeat exactly
the musical intervals sung by other birds, but to
be unable to render the sounds (especially in the
case of harsh sounds) with accurate intonation.
Again, some of the singers appeared to whistle
their own songs, and then to supplement these
with the addition of sounds borrowed from the
cries of other birds.

The blackbird and missel-thrush exemplify this
method. But the blackcap, whose voice is as full-
toned as that of either of these two, adopted an
opposite mode, and commenced its songs with soft
imitations of other birds, to conclude them with its
own full whistles. I attempted to draw no deduc-
tions from my first observations, knowing that



INTRODUCTION



general statements cannot justly be founded on
the behaviour of a few individuals.

During a period of eighteen months I went on
with my work of recording, but at considerable
personal inconvenience. My profession demanding
all the middle hours of week-days, there were com-
paratively few opportunities for making notes at
that time ; but on nearly every fine morning, the
whole year through, I was early abroad in the
woods and fields, armed with telescope and note-
book ; and when the evenings were long enough,
the same course was pursued. Occasionally, my
notes were all entered in a ledger, as though to
the account of the several birds observed. In the
spring of 1889 I began to condense the results of
this work, and found myself in the possession of
records of the songs of a large number of our
commoner birds, heard in Gloucestershire and also
in or near Bath, Weston-super-Mare, Clifton, and
Bournemouth. I had notes on the songs of some
seventy thrushes, nearly sixty robins, many star-
lings, skylarks, finches, and other singers. A care-
ful comparison of the records revealed that imitative
birds had reproduced the cries of other birds especi-
ally frequent in their haunts. The skylark had
been partial to field-birds ; the robin to those of



EVOLUTION OF BIRD- SONG



the thicket ; the starling to those of the field as
well as to those of the town. On further tabulation
the notes betrayed indications that summer visitors
to this country are imitated more often in spring
and summer than in autumn and winter, and this
would seem reasonable to any one sufficiently familiar
with song-birds to understand that many of them
are creatures of intelligence, endowed with accurate
memories and considerable powers of observation
and mimicry. The various aspects of imitation,
and instances of its occurrence, are discussed in the
chapter on "The Influence of Imitation," towards
the end of this book. In pursuing my studies of
the notes of birds, I observed a good deal of bird-
life, and soon found that certain cries were employed
by birds as call-notes, and others for the purpose
of expressing alarm facts which have long been
familiar to ornithologists. I also noticed that birds
of a species would generally behave in much the
same manner on the same occasions, and that par-
ticular cries were sometimes employed to express
certain degrees of emotion, some call -notes being
evidently of a more urgent meaning than others,
and some alarm -cries being similarly more im-
portant. There were other curious features in
these call-notes and " alarms," which are respectively



INTRODUCTION



stated in Chapter II., on " Alarm -notes," and
Chapter IV., on " Call-notes."

Between these chapters will be found one treat-
ing of the influence of combat. This feature is
difficult to discuss with anything like precision :
incidents have been adduced tending to show that
the pugnacious instinct has some influence on the
use of the voice.

I soon found that young birds acquire first the
call - cries and alarm - notes of their respective
species ; that in each species these notes are much
less liable to vary than are the songs ; and that in
different species physically allied, they are more
alike than are the songs of those species. Another
most interesting feature, and one which I commend
to the attention of ornithologists everywhere, was
the prominent occurrence of a particular cry in one
species ; its occurrence in a less marked form in
some one or two allied birds, in which another cry
might be the most pronounced ; and the utterance
of this second cry by some other allied birds, which
had not the first-mentioned note. I could trace
this to some extent in the thrushes, but more especi-
ally in the finches. These facts will be appreciated by
naturalists, as bearing on the question of a common
ancestry of species. For purposes of suggestion I



EVOLUTION OF BIRD- SONG



have traced family resemblances of this nature in
species physically allied, and in others not thus
related. I also read of certain birds which inherit
their songs, and I was acquainted with several
which inherit their alarm-cries and call-notes. The
subject to which these matters relate, the influence
of heredity, is discussed at length in chapter vii.
There can be no doubt that heredity is as certain
in perpetuating the cries of some species as is
imitation in determining the whole character of
the songs of others ; the extent to which these
influences prevail in the several orders of birds has
yet to be traced. Variation, towards which feature
the males of so many species tend, seems to be the
parent of imitation ; it is considered in a separate
chapter.

"The Music of Bird -song" is the concluding
theme. It has to some extent been discussed in
the chapter on Imitation ; but in the Appendix will
be found a transcript of many strains which I
heard sung by the better singers.

The reader will observe that I have not relied
wholly upon my own observations, but have quoted
those of numerous well-known authorities, of good
report in the scientific world. I read no book at
all on the subject until 1889, when I had com-



INTRODUCTION



menced my comparisons between the various records.
Since that time very many works have been perused,
but only in a few have any acceptable records been
found. Even Mr. Simeon Pease Cheney's work,
full of musical notation, hardly touches upon
imitation, and has no observations on the influence
of heredity. There are poetical writers who de-
scribe such incidents as the lark soaring in the sky,
pouring out his soul in music for the little brown
mate trustfully listening in her nest ; but they never
remark that the lark utters a chattered song when
he fights. There are many ornithologists who name
certain birds as imitative ; but when their descrip-
tions are examined, the reader can only infer that
the mimics were caged specimens. I have nothing
to say about caged birds, except in quotation, or in
relation to experiments with young birds, or where
such arbitrary notes as those of the collared turtle-
dove, young pheasant, and young partridge are
concerned. In making my investigations, various
ideas on the causes of certain features of the exer-
cising of the voice in birds occurred to me. These
are set out in chapter vi., on " Noticeable Incidents
connected with Bird -song." One of the most
marked of these features was the construction of
certain songs by the rapid repetition of call-notes.



EVOLUTION OF BIRD-SONG



This subject seems to me sufficiently important to
warrant its elucidation in a separate chapter (v.), on
" The Simplest Songs."

The scheme of this work is as follows: A
hypothesis on the first occurrence of voice in any
animal is stated, and the influence of combat in
perpetuating it is then mentioned. The inherited
distress-cries of young animals (probably produced
long after the occurrence of the voice in adults),
and the retention of these cries for the purposes of
call-notes, lead to the consideration of the simplest
songs, which are mere repetitions of the call-notes,
and to those in which variations occur, and which
probably are affected by the influence of imitation.
The purposes of imitation are then discussed. The
scientific value of the notes of birds, as bearing
upon the ancestry of species, is considered at
length.

By " bird-song " I mean the whole range of the
voice in birds. Songs I have defined as vocal
utterances, not being alarm-cries or call-notes. 1

The word " phrase " (as I have employed it in
this work) does not mean a strain in music, but a
period of song ; so that, if a bird sang a few notes
at one time, then paused and sang them again, and

1 Zoologist, July 1890.



INTRODUCTION



so on, each repetition would be a " phrase." Thus
it is possible that many phrases could be the same
song exactly, repeated at intervals, or the song might
be varied, but it would be a separate phrase at each
time of utterance. It is important that this defini-
tion of the phrase should be remembered.

A " strain," on the other hand, means a succession
of sounds uttered in a definite order, and which may
be repeated, perhaps several times, in one phrase, as
commonly occurs in the very long phrases of the
skylark.



CHAPTER I

THE ORIGIN OF THE VOICE

THE great diversity of the voice in animals, and the
extent to which it is inflected by individuals, suggest
that it is particularly liable to be influenced by the
vicissitudes of the struggle for existence, and to
be necessarily modulated in accordance with the
requirements of each animal or species by which
it is employed.

This modulation is very apparent. We hear
from every side the notes of various animals, as
cries for succour, songs apparently of love, and
notes equally suggestive of triumph or of fear
all of them exactly suited to the purposes for
which they are uttered. But it does not follow
that these sounds have always been employed for
the same purposes, nor that they have always
been uttered in the present modes ; for we observe
among birds, at least, prevalent changes not only



THE ORIGIN OF THE VOICE 13

of musical pitch, but of other vocal characters, in
the young as well as in the adults. Nor must we
hastily assume that the voice itself has always been
coeval with even the higher forms of animal life
upon the earth. On the contrary, there are grounds
for believing that in the epoch when the highest
forms were the amphibians and reptiles, the voice,
properly so-called, had not yet been heard in the
world.

Charles Darwin was of the opinion that the
first vocal sounds were involuntarily produced. In
his work, The Expression of the Emotions, pp. 83
and 84, is the following observation : " When the
sensorium is strongly excited, the muscles of the
body are generally thrown into violent action, and,
as a consequence, loud sounds are uttered, however
silent the animal may generally be, and although
the sound may be of no use. Hares and rabbits,
for instance, never, I believe, use their vocal organs
except in the extremity of suffering ; as when a
hare is killed by a sportsman, or when a young
rabbit is caught by a stoat. Cattle and horses
suffer great pain in silence, but when this is excess-
ive, and especially when associated with terror,
they utter fearful sounds. Involuntary and pur-
poseless contractions of the muscles of the chest



14 EVOLUTION OF BIRD-SONG

and glottis, excited in the above manner, may
have first given rise to the emission of vocal
sounds."

The most violent contractions of the muscles of
the chest and glottis would certainly have occurred
during combat, and it is therefore fair to assume
that the voice was first produced during the fights
of animals, although possibly its earliest tones were
little more than coughs or grunts, or a hoarse
murmur due to panting. Darwin observed (tbid.\
" The principle also of association, which is so
widely extended in its power, has likewise played
its part. Hence it follows that the voice, from
having been habitually employed as a serviceable
aid under certain conditions, inducing pleasure, pain,
rage, etc., has commonly been used whenever the
same sensations or emotions are excited under
quite different conditions or in a lesser degree."

We may be certain that the perception of a
threatened attack is only a mental anticipation of
the combat which experience, or inherited instinct,
suggests as a probable consequence of the approach
of an enemy. It is easy to imagine that, among
animals which survived by the agency of their speed,
the excitement due to the approach of an enemy
would cause an involuntarily increased rapidity in



THE ORIGIN OF THE VOICE 15

the movements of the lungs ; and if the animals
were of large size, a kind of snorting, like that
of a horse, might thereby be produced ; or perhaps
the initial movement of certain limbs, like the
twitching of the wings of a terrified falcon, would
be occasioned. The development of clear cries
from snorts or grunts must be regarded as a pro-
cess of very slow progress. But we must remember
that there are several widely distinct races of
animals whose only attempt at vocal utterance is
the employment of a yet simpler mode of expres-
sion a mere puff or hiss caused by the toneless
expulsion of air from the lungs ; and be it observed
that in these instances, as well as in those of its
occurrence in animals possessing voices, the sound is
invariably due to anger or to fear. The common
tortoise, so often kept as a pet in English gardens,
when suddenly alarmed withdraws its head and
limbs rapidly within its shell, and at the same
time a kind of short hiss is heard, especially if
the animal has been frightened by being grasped
in the hand. In serpents, a hiss is the common
expression of anger. Among birds, the same feel-
ing is sometimes expressed in a similar tone, but it
is rarely employed except by birds sitting on their