Henry Eliot Howard

“ We are apt to think of migration in terms of the Warbler that enlivens our hedgerows in the spring after travelling hundreds of miles from the south, or of the Redwing that comes from the far north and seeks its food during the winter on the meadows, or perhaps of the American Golden Plover that each year covers a vast expanse of ocean in its journey from its breeding ground. The length of the distance strikes the imagination and constrains us to focus attention upon the extremes. ”

“ Now there are two ways by which the male can make himself conspicuous—by occupying such a position that he can be readily seen, or by producing some special sound which will be audible to the female and direct her to the spot. The former, by itself, is insufficient; in the dim light of the early dawn, when life is at its highest, and mating proceeds apace, what aid would it be for a male to perch on the topmost branch of a tree, how slender a guide in the depth of the forest? ”

“ She, meanwhile, walks or runs—as a rule it is more of a sedate walk—amongst the dense undergrowth, at times threading her way through the branches of some small bush, occasionally pecking, or pretending to peck, at something as she passes, with an air of complete indifference to the attractions of her lover, never even pausing to look behind. He, however, sometimes leaves her either to sing, or with quick darting flight to chase away another male, who, in his opinion, has approached too closely, or for a more lengthened period, possibly to annoy other males engaged in the same task as himself. ”

“ But with the advent of spring a change comes over the scene: flocks disperse, family parties break up, summer migrants begin to arrive, and the hedgerows and plantations are suddenly quickened into life. The silence of the winter is broken by an outburst of song from the throats of many different species, and individuals appear in their old haunts and vie with one another in advertising their presence by the aid of whatever vocal powers they happen to possess—the Woodpecker utters its monotonous call from the accustomed oak ”

“ Manifestly the impulse to brood could only have developed strength in so far as it fitted in with all the other factors that make for survival; and the principal factor in the external environment seems to be the territory. How could the young have been freed from the risk of exposure if the impulse to brood had not been so strongly implanted in the parent? How could the impulse to brood have been free to develop if a supply of food had not been first insured? How could the supply of food have been insured if numbers of the same species had been allowed to breed in close proximity? ”

“ All of this we observe each season, and our thoughts probably travel to the delicate piece of architecture in the undergrowth, or to the hole excavated with such skill in the tree trunk; to the beautifully shaped eggs; to the parent birds carrying out their work with devoted zeal—in fact, to the whole series of events which complete the sexual life of the individual; and the attachment of a particular bird to a particular spot is readily accounted for in terms of one or other of the emotions which centre round the human home. ”

“ I think, no question that the male whilst travelling to its breeding grounds, and, even after its arrival, whilst in search of a territory, sings but little—and that little lacks the persistency characteristic of the period of sexual activity. Yet, when a suitable territory is eventually secured, the nature of the bird seems to change; for, instead of being silent and retiring, as if aware of some end not fully attained, it not only makes itself conspicuous but advertises its presence by a song uttered with such perseverance as to suggest that that end is at length attained. ”

“ Tree-Pipits, Whinchats, and Willow-Warblers pass from tree to tree or flit from bush to bush—and all in a north-easterly direction. They do not sing, they are restless, and, judging by their behaviour, they are anxious to conceal their presence, not to make it known. Yet we know that when they reach their destination, as presently they will, all this will change; that each of them will employ every means at its disposal to make itself conspicuous; and that each, as far as it is able, will resist intrusion on the part of other species. ”

“ For a minute let us consider it simply expressive in practical form of a mind overburdened with the mental image of a nest and all that pertains to its construction, and that it is in no way associated with any sexual passion. Assuming this, then, why do we not find the same action in the female? Assuredly to her the nest must mean as much, if not more, than to the male; and if this was only an expression of delight on the part of the male at the return of the breeding season, it is only reasonable to suppose that we should find the same or some similar action in the female. ”

“ Often have I searched in vain; in gorse it is well-nigh hopeless and best avoided, in osier-beds and waste swampy ground patience only is required to crown one's efforts with success. Crawling amongst the long tangled undergrowth into the middle of hazel bushes, where the foliage is so dense that light can scarcely penetrate. I attempt to follow the sound. Each time on hearing the squeak I crawl a little closer until quite certain that the little bird is within a few inches of my face, but quite uncertain whether to the right or left or straight in front of me ”

“ Remove a young one from the nest, when old enough to recognise and reply to its parents, and notice the effect produced. The male approaches within a few yards of you, twists and turns on the branches, or flutters and flaps along the ground, uttering short snatches of its song identically the same as when courting, but more often squealing and imitating other species. Here, then, we have a species which performs, not only during the period of courtship, but also at other periods of excitement in its life, a remarkable series of both bodily and, if I may use the term, vocal antics. ”

“ The life of the male from the time that the female commences to lay is a most methodical one; this seems to be the rule of the whole species, and I can nowhere find any deviation from it. He adheres with wonderful precision to the boundaries of his territory, where he can be seen morning after morning in the same tree, pouring out his monotonous song, through May, June, and the greater part of July, even after the young have left their nest and disappeared—some, perhaps, to their winter homes. ”

“ As many as eight or nine collect together, some adult, some immature, the adults apparently very angry, scolding vigorously, their feathers ruffled and their tails spread out; the onlookers also join in the scolding, the commotion being quite unusual for bird-life. So absorbed have they sometimes been that I have crept into the middle of them before they have noticed me, when they have reluctantly dispersed. I once found an empty nest from which the young may have been taken, but there were no dead bodies round it to show that a tragedy had occurred ”

“ Let us suppose that there is an area inhabited by one species; that the number of inhabitants has reached the maximum that the means of sustenance will allow; and that the season of reproduction is drawing to a close. The position will then be as follows. All the available breeding ground is divided into territories; each territory is occupied by one unit, the family, and each individual is able to fend for itself; changes both internal and external begin to take place, the gregarious instinct comes into functional operation, and the supply of food diminishes—that roughly is the position. ”

“ But just why a Marsh- Warbler is gifted with a voice that is so beautiful and varied, whilst the Grasshopper- Warbler must perforce remain content with a monotonous trill; just why the tail feathers of the Snipe have developed into an instrument, whilst the Pied Woodpecker has developed muscles which enable it to make use of a decayed branch as an instrument—we know no more than we do of the nature of the forces which lead the ReedWarbler to weave its nest to reeds, or the caterpillar of the Elephant Hawk Moth to assume so peculiar an attitude when disturbed. ”

“ Waiting for about ten minutes, he presently appeared climbing up the middle of the bush again till he got to the top; there he sat sunning himself, his feathers swollen out, and his form perfect, as beautiful a creature as you could see.
To see them in all their beauty birds must be unconscious of your presence; there is a vast difference between a bird as he is usually seen with his feathers lying flat on his body, and a bird that is really at rest, unconscious of the presence of any human being ”

“ If there had been no flock, if a few solitary individuals had appeared here and there and had established themselves in different parts of the meadow, one would have had no definite evidence of the strength of the impulse in the male to seek a position of its own, one could only have argued from the general fact of males flocking in the winter and isolating themselves in spring that something more than accident was required to explain so radical a change. ”

“ A male intrudes, and the intrusion evokes an immediate display of irritation on the part of the owner of the territory, who, rapidly uttering its song and jerking its wings, begins hostilities. Flying towards the intruder, it attacks viciously, and there follows much fluttering of wings and snapping or clicking of bills. At one moment the birds are in the tree-tops, at another in the air, and sometimes even on the ground, and fighting thus they gradually approach and pass beyond the limits of the territory. ”

“ The welcome note of the male will be heard in the morning after his arrival; there may be fog, or there may be a cold north-east wind blowing, but no matter what the weather, there, in the tops of the highest trees, he will be, singing intermittently, a restless little fellow, looking, as he sways backwards and forwards, his feathers ruffled with the wind, almost too delicate to stand the cold ”

“ Now certain facts are presented to observation which enable us not only to understand the nature of the change that is wrought in the history of the species, but to foreshadow, with no small degree of certainty, the extent of that change. I suppose that it has come within the experience of most of us to observe, at one time or another, the ebb and flow of a given species in a given district. ”

“ The Curlew, when surprised, utters a cry with which most of us, I suppose, are familiar; but when with lowered head it drives away another individual from the feeding ground, it gives expression to its feelings by a low, raucous sound, which again is different from its cry when a Common Gull steals the arenicola that has been drawn out of the mud with such labour. ”

“ I have sometimes found the males, early in April, in a quiet corner on the outskirts of small woods gathered together on the low bushes, there sunning themselves, with their feathers relaxed and fluffed out in their peculiar manner. Each male on his arrival regards a space of ground within certain limits as his peculiar breeding territory, and if two, arriving during the same night, happen to have settled in the same locality, a severe fight for possession ensues. ”

“ We must remember, however, that fighting continues throughout the whole period of reproduction. Even after the discharge of the sexual function has ceased, and the female is engaged, in incubation or in tending her young, the male is still intolerant of intruders; and it is difficult to believe that, at so late a stage in the process, a female could be any attraction sexually to an unpaired male. But apart from any theoretical objection, there remains the fact—namely that there is no evidence that a male, after having once paired, is liable to be robbed of its mate. ”

“ For, watch a Blackcap on his arrival, or any other male before actually having mated, and you will see that his or their movements point to the fact that all the thoughts are concentrated on the one object—the possession of a female—and to attain this object all their powers, chiefly vocal, are directed. Any thought of the construction of a nest—if really there is at all at this period, which I am inclined to doubt—must be in comparison with the other momentous event in the bird's life wholly insignificant. ”

“ Inasmuch, then, as the occupation of a territory serves to remove all possibility of permanent separation, I suggest that its evolution has afforded the condition under which this beneficial procedure has developed—free to mate when they will, free to seek food where they will, free to pursue their normal routine of existence, and to meet all exigencies as they arise in their ordinary daily life—whilst free to do this, their future, as a pair, is nevertheless secure. ”

“ So far as can be seen, however, the impulse to seek isolation with its correlative territory, leads to constant modification in the breeding range of most species. The occupation of the small space of ground which each individual requires, the extent of which has been gradually adjusted to suit the needs of different species, results in expansion not only in one direction but in every direction, and not only in one season but in every season. And if there were no complications in the external world this expansion would proceed, as we have seen, with astonishing rapidity. ”

“ The cliff-breeding species—Guillemots, Razorbills, and Puffins—are difficult to investigate because individuals vary so little, and the sexes resemble one another so closely; yet, despite these difficulties, we can gain some idea of the general purport of their activities. But when the ledges are crowded and the air is filled with countless multitudes, how is it possible to keep a single bird in view for a sufficient length of time to understand its routine? ”

“ Warblers alter their mode of life, and in the osier bed, or amongst the elders, seek their food together in peace; Finches, Buntings, Pipits, and Wagtails, though food is everywhere abundant, gather themselves together respectively into bands which, as winter approaches, grow into flocks and even into composite flocks; and as the Warblers leave for the south, so their places are filled by flocks of Thrushes and Finches from the north. In whatever direction we turn, when the days begin to shorten, it is the community, not the individual, that thrusts itself upon our attention ”

“ Hence it is clear that the nature of a bird when on migration is not quite the same as it is when its destination is reached; that the positions occupied from time to time during the journey carry no meaning, or, rather, are not brought into relation with its life in quite the same way as is the position which it finally occupies; and further, it is clear that the interest it displays in other species undergoes a somewhat remarkable transformation when at length its destination is reached. ”

“ I seek only to ascertain whether the impulses that are concerned in the securing of a territory, and in the search for society, bear any relation to the problem as a whole. I hold that the origin of migration is not to be found merely in conditions peculiar to a remote past, but that the conditions inhere in the organic complex of the bird, and are thus handed down from generation to generation. ”

“ Now a male may leave its territory for three reasons—to pursue an intruder, to join the flock on neutral ground, or to find the necessary means of subsistence on other feeding grounds. On each of these occasions it hears the song of, and is in close contact with, other males; and if the relationship of which we are speaking be really exclusive of cross-correlation, its instinct ought to respond with the customary freedom. But what happens? A male pursues its rival, betraying much emotion and singing extravagantly, until the boundary is passed, when emotion subsides and it is silent ”

“ The various steps by which the territory is not only established but made secure from invasion, imply an inherited nature nicely balanced in many directions—first of all the male must be so attuned as to be ready to search for a territory at the right moment; then it must be capable of selecting a suitable environment; and, having established itself, it must be prepared to defend its area from a rival, and to resist encroachment by its neighbours—and if it failed in any one of these respects, it would run the risk of failure in the attainment of reproduction. ”

“ The Blackcap and the Garden-Warbler are constant rivals, and the scenes which can be witnessed when the two meet in competition are interesting from many points of view. The birds not only pursue and fight with one another, but their emotional behaviour reaches a high level of intensity—excitable outbursts of song are indulged in, tails are outspread, wings are slowly flapped, and feathers raised—in fact the attitudes assumed are similar in all respects to those which occur during the contests which are so frequent between the respective individuals of each species ”

“ But what is the condition under which the pugnacious instinct of the female is rendered susceptible to stimulation? It cannot be merely the presence of a male ready to breed, for then there would be endless commotion amongst the flocks of Chaffinches or of Lapwings which in March are composed of both sexes, including even males that have secured territories. There must be some other circumstance; and, judging by experience, it is to be found in the territory—a male, that is to say, in occupation of one, is the condition under which the inherited nature of the female is allowed free play. ”