The British Warblers A History with Problems of Their Lives/Grasshopper-Warbler
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GRASSHOPPER WARBLER
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GRASSHOPPER-WARBLER.
Croatian, Trotenjara kobilicarka; Czechisch, Rákosnik zeleny; Danish, Busksanger; Dutch, de Sprinkhaan-Rietzanger; French, Bec-fin locustelle; German, Heuschrecken-Rohrsänger; Hungarian, Réti tücsökmadár; Italian, Forapaglie macchiettato; Norwegian, Græshoppe-Sanger, Busk-Sanger; Polish, Trziniak swierszczyk; Russian, Swertschok; Swedish, Gräshoppsångare.
DESCRIPTION OF THE PLUMAGE.
Adult Male in Spring.—The upper parts are of a uniform darkish red olive brown, each feather having a blackish brown centre, and this centre is most conspicuous on the crown and back, fainter on the long upper tail-coverts, and almost disappears on the back of the neck. The upper surface of the tail is of the same hue as the upper parts, but of a slightly darker brown, narrowly edged with lighter olive brown, and marked with faint transverse bars—the shaft of the feathers being dark reddish brown. The lores are olive grey, a superciliary streak, which disappears behind the eye, is a whitish olive yellow; cheeks and ear-coverts are darkish olive brown, with very indistinct light shaft stripes, and the side of the neck is the same colour as the upper parts but slightly lighter and unspotted. The wing-feathers are the same colour as the upper surface of the tail, broadly margined with the same colour as the back, and slightly reddish at the root of the outer primaries, forming an indistinct patch, but disappearing at the tip of the primaries and inner web of the secondaries. The throat is whitish buff, crop region buffish olive yellow, centre of breast and abdomen whitish, blending into whitish buff on the long under tail-coverts, the latter being furnished with a dark centre, which, however, does not reach to the tip of the feathers. The under surface of the tail is brownish grey, suffused with lavender grey. The sides of the breast and body are of the same colour as the back, but rather lighter and unspotted, though at the roots of the tail the feathers have dark but not very conspicuous centres.
Adult Male in Summer.—The upper parts are of an olive greyish green, very slightly tinged with yellowish umber, each feather having a dark brown centre, most conspicuous on the crown and back, but more indistinct on the nape and upper tail-coverts. The upper part of the tail is uniform, the olive umber being stronger, and the shafts a lavender brown. The wings are a dark greyish brown, but the broad margins of olive greyish green make the closed wing look almost uniform in colour; the first and second primary each have a whitish brown edge. There is an indistinct whitish ochre superciliary stripe disappearing behind the eye. The lores are greyish, sides of 
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Adult Female in Spring.—The upper parts are of a uniform lightish olive umber slightly washed with a rusty colour. The marking on the back and shoulders is the same as in the male and well pronounced, the dark centres to the feathers forming on the crown about six narrow stripes, which, though plain, are not very conspicuous. The back of the neck is unspotted and the dark centres are very inconspicuous on the rump and upper tail-coverts, whereas the transverse bars on the tail-feathers are easily seen. The wing is brownish black on the innermost secondaries, with a fairly broad edge of the same colour on the upper parts, though more rusty. The outer edge of the first large primary is whitish buff. The lores are dusky, and there is an indistinct superciliary stripe. The feathers on the eyelid are whitish buff, throat whitish, sides of the head, neck and body rich gamboge olive, darkening towards the tail, with faint dark centres to each feather, and blending into whitish on the centre of the abdomen. The crop is fawn colour, with small brown spots, and suffused with a beautiful vinous tint. The under tail-coverts are whitish buff with dark brown centres, both colours well pronounced. The under part of the tail is brown, washed with a faint lavender grey.
Fledglings.—The upper parts are very much like the adults, only slightly richer in tint and distinctly olive rust colour—not olive grey. There is a distinct, though not prominent, yellowish superciliary stripe, which soon disappears behind the eye. The ear-coverts are light olive ochre, the sides of the head and neck whitish, washed with olive yellow, and the throat whitish. The colour of the under parts varies considerably in different specimens, probably due to sex. In the one case the general colour is whitish, the crop, which is furnished with small brown spots, is washed with light olive brown, the same colour extending down the flanks, and the under tail-coverts olive buff, marked boldly with brown longitudinal spots; in the other the colour is whitish, washed with light olive buff, giving a rich tone which extends down the flanks: the crop is unspotted.
The under tail-coverts are almost light buff, inconspicuously marked with brown longitudinal spots. The tail-feathers are brown, slightly lighter towards the tip, the under surface with lavender. There is no downy plumage in the young.
The plumage of both sexes is in many ways interesting, since it shows considerable variation. The spots on the throat are not confined to any one age or sex. The majority of the males are similar to the one described first, but vary considerably in intensity of colouring, an absence of spots and a general richness of tone being apparently complementary to one another. Between those that are heavily spotted and those that have the feathers perfectly clear the intermediate grades are numerous. The second one described simply marks a stage in the deterioration of the plumage which commences directly coition has taken place and continues up to the moult. The female described appears to be the more uncommon form, and I have only seen one other female that had this peculiarly rich colouring, and hitherto I have seen no male that could compare with it. The plumage of the young is also interesting, since an absence of spots in their case appears to be equivalent to a different tone of colouring. Whether all the members of a brood develop the same colouring, or whether the variations are sexual or sporadic, further investigation can alone show.
GEOGRAPHICAL DISTRIBUTION.
Owing to certain peculiar characteristics of this species, naturalists acquainted with its habits are comparatively few, and consequently our knowledge of its distribution is incomplete. We may, therefore, find that certain features in this distribution, which at the present time appear to us anomalous, may, as our knowledge increases, be partly or possibly wholly explained.
Great Britain is apparently one of the principal breeding grounds, although over the whole area it can only be described as locally distributed. We find it rare in Cornwall, but in the remainder of the southern counties, including Devon, a regular but local visitor. Further north it appears to be more common, and in parts of Oxfordshire. Cambridgeshire, Gloucestershire, Worcestershire, Shropshire, Yorkshire, Cumberland, Durham and Northumberland it is numerous.
The greater part of Wales is unsuited to its habits, consequently it is very local; I have, however, frequently heard it in Anglesey. Proceeding north, over the border, we find it gradually becoming scarce; south of an imaginary line drawn from the mouth of the River Clyde to the Firth of Forth locally distributed, but north of this line rare, and we lose sight of it at Arisaig on the mainland and in the north-west of Skye. In the Orkneys, Shetlands and Western Isles there is no record of its occurrence. Westward we find it occurring in the Isle of Man, and then we come to a large breeding ground in Ireland, where it is generally distributed, but especially numerous in the counties of Antrim, Dublin, Wexford and Waterford.
The task of forming a systematic distribution outside the British Isles is by no means an easy one, and the difficulties face us directly we cross the Channel.
Commencing with Morocco and Algeria, probably its most southern breeding range, we find it sparingly distributed. In Spain we find it occurring in Granada, Malaga, Murcia, Valencia, and common in the marshes of Santander, also wintering in the more southern provinces. The records from Portugal are very scarce, and the bird apparently only visits the country occasionally: it has been seen near Coimbra.
Crossing the Pyrenees, we find it more generally distributed and in parts of France common, for instance, in the provinces of Finistère, Cotes-du-Nord and Morbihan, also along the banks of the River Var and in Savoie.
Belgium is only rarely visited; it has been found in the province of Namur. The same applies to Holland to some extent, but here, perhaps, it is rather more frequent in its visits and breeds near Haarlem and Cromvoirt: I found no trace of it in Texel.
Continuing northwards, we find it occurring on migration in Heligoland. The records, however, become very scanty as we still continue north. In Holstein it is common, but rare in Schleswig. It has been obtained on the Island of Alsen. In Denmark it has apparently only been found during the autumn migration, specimens having been killed at a lighthouse on the coast of North-west Jutland, at a lightship in the North Kattegat and on the Island of Anholt. In Sweden it has not hitherto been found, but reappears as a breeding species, though rarely, in the southern parts of Norway, confining itself principally to the Jäderen, Christiania and Dröbak districts.
In Germany it is generally distributed. Working from west to east, we find it rare in Hanover, occurring on the River Marke, and not rare in Baden. The districts near the Elbe and its tributaries are apparently the most frequented, especially in Anhalt, Brandenburg, Mecklenburg, near Rostock and Parchim, and Altenburg. We find it again in Hessen, and as might be expected, it is partial to the Danube and its tributaries near Augsburg, Lauingen and Munich, and is not uncommon in Silesia.
It visits parts of Switzerland, breeding regularly in the low regions of the basin of the River Aar and the River Thur, in the districts near Geneva, and in the valleys of Hasli and Ursern. On migration it is found as high as the Alpine regions.
Italy is little frequented, and the bird appears to confine itself principally to the north-western districts, where it is found in Lombardy, in the Brembana Valley, Piedmont, Liguria, the neighbourhood of Nizza, and Modena. Little is known of it in Central and Southern Italy, but it has been found near Florence in September. From Corsica, Sardinia, Sicily, Greece, and the Balkan provinces there are no records.
In the Austro-Hungarian Monarchy it is not common, principally inhabiting the Hansag swamp, and localities in Pozsony, Feher, Also-Feher and Hunyad. As we get further east, towards Galicia, it again becomes common, and leaving Austria, we come to what is apparently its largest breeding ground—the Russian Empire.
Commencing with Poland, we find it common, especially in Lublin, then proceeding north, not rare in the Baltic provinces, the provinces of Pskov and St. Petersburg; still further north we trace it to the south-east of Lake Onega and Ustiug Weliki in the province of Vologda. It is more numerous and generally distributed in the central provinces of Jaroslav, where it breeds on the islands of the Volga and near Rostov, Tver, Moscow, Smolensk, and Tula, also in the district lying between the Rivers Volga and Oka, but from the middle Volga valley there are no records. In the more southern parts it is found in the provinces of Kiev, Volhynia, Tchernigov, also along the banks of the Rivers Bug and Dnieper. In the Ural district it is commonly distributed round Bogoslovsk, the tributaries of the River Sosva, and in the province of Perm; it is also found in the Orenburg district at the base of the south-west Ural Mountains, in the plains of the Rivers Sakmara and Ilek, and in the middle valley of the River Ural. In the Caucasus it is common in the vicinity of Stavropol and the northern slopes, but there are no records from Trans-Caucasia. Crossing the Caspian Sea, we find it occurring in the Mangishlak Peninsula, breeding along the west of the delta of Sir Daria, and in Western Thian-Shan, visiting Iskandar Kul and the Northern Pamirs; and still continuing east, we find it on Lake Ala Kul, and finally lose sight of it on the southern slopes of the Altai Mountains. There is much to be learnt about the southern range; at present it has not been found in Egypt or Tunisia, but in winter it visits Morocco and Algeria.
Now it must be evident to any one who follows these details, and at the same time bears in mind certain habits of this bird referred to in the text, that we have in these habits a possible explanation of some of the facts which are otherwise somewhat inexplicable. Since, therefore, it is probable that at some future date a more intimate acquaintance with these habits will influence and expand our ultimate knowledge of the distribution, and in order that the relation they may bear to the present incomplete state of this knowledge may be fully realised. I propose to briefly allude to them again.
A partial and in many places almost complete cessation of the song after pairing has taken place until the young leave the nest.
A very erratic appearance in any one particular district from year to year.
Very skulking habits after eight o'clock in the morning until the evening and during incubation throughout practically the whole day.
In countries where the bird is seen in the spring and autumn migration, but is not supposed to breed, especially where the autumn migration is a comparatively early one, it is possible that an explanation may be found in the first of these habits, the bird being overlooked during the quiet period. But after due allowance is made for these habits, and the resultant unsatisfactory state of our knowledge, the geographical distribution remains an interesting one.
It is difficult, for instance, to understand why in Italy and Hungary—countries affording natural features eminently suitable to its habits—the bird is scarce. The great plains of Hungary and the banks of the Danube always appear to me to be particularly adapted to it, yet I cannot believe that in a country where the natural life is studied with so great an interest the bird is overlooked. These remarks apply equally to the Netherlands, and to some extent Belgium.
The migration across Heligoland, where it occurs not infrequently in March, April, May, August, September and October, is completely at variance with the present knowledge of its distribution. According to Heinrich Gätke, the spring migration in Heligoland invariably proceeds from west to east; but in the case of this species, where? A glance at the map will show that we are here near 55° N. latitude, above which, until we reach 25° longitude, the bird can only be described as rare. Those individuals, therefore, that cross the island—and the evidence tends to show that their numbers are considerable—must, after leaving, turn southwards into Germany, or continuing east, use this as their route to the Baltic provinces and Central Russia. But the winter quarters, as far as we know, are in Morocco, Algeria and the South of Spain. Is it, then, conceivable that in order to reach its summer home it would traverse so great and unnecessary a distance? In the opinion of Heinrich Gätke, the majority of spring migrants from South Africa on their way to Siberia do not pass Heligoland, but go direct. It is probable, therefore, that there is much to be learnt concerning the northern breeding range.
LIFE-HISTORY.
Different species vary very considerably in character; some are lethargic and dull, others are the possessors of great nervous development, so that the study of some is more likely to lead to the solution of Nature's problems than the study of others. To that class in which the different faculties seem to be specially active belongs the present species, and for me there is in all their movements, in each action of the short life they yearly spend amongst us, a fascination difficult to account for, unless it be in part due to a growing appreciation of my ignorance of all that they have to teach me.
Arriving between April 17th and 23rd, they visit us in considerable numbers, yet in a very erratic manner, favouring one particular district one year and deserting it the next, neither are they the least influenced in this respect by climatic conditions; for instance, in the years 1897 and 1903 they were so plentiful that during the first few hours of daylight their favourite haunts appeared to be alive with them, yet these two years were respectively very hot and dry, and very wet and cold. In Worcestershire, where I have principally studied this bird, they arrive during the night, and commence to sing, uninfluenced by the weather, at daybreak; and in the immediate neighbourhood of the spot they settle in they generally breed, although occasionally one appears to be a wanderer, singing in a hedge by the roadside, yet passing on before the next morning. If it were not for its song, which is penetrating and arrests attention, it would be a most difficult bird to find, for it is peculiarly skulking in its habits, especially after eight o'clock in the morning until about four in the afternoon. It spends the greater part of its time either on the ground in the dense undergrowth, creeping in low thick bushes a few feet high, or searching tall thick hazels and hedgerows for food ten or twelve feet from the ground, but never appears to frequent trees; and has at all times, even when unconscious of any human presence, a great aversion to showing itself in the open. During incubation, when the song partly ceases, these skulking habits are more marked, since both sexes go to considerable trouble to conceal themselves.
They choose for themselves different and very varied spots, 
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On their arrival the males can easily be detected by their song—for applying the word "song" to the vocal efforts of my friends I must apologise. I know not what other word describes it—which when once heard can never be forgotten, and from which they have earned the name "Grasshopper"; yet when with bill wide open and body quivering they utter their monotonous "reel" there is little resemblance to the insect. A more minute knowledge of their ways is required to enable one to appreciate whence the name originated. They are by no means difficult birds to approach, and with ordinary precaution it is possible to get concealed quite close to them, and to hear the low whisperings from which they take their name. Let us suppose for a moment we are concealed within a few yards of one of them. There, on a branch low down in some nut-bush, he sits wrapped in meditation; now he commences to sing, and the power thus expended is apparent from the vibration, which is becoming almost painful to the ears, when he stops, and in turn in the far distance we hear others answering, first on one side, then on another. But watch him closely; with throat still distended and bill slightly open, he turns his head from side to side, and the sounds from our imaginary birds in the distance coincide with the turning of his head; thus the truth dawns upon us. He is certainly a wonderful ventriloquist, and though perhaps not conscious of his powers, yet he is most deceptive, and I have often been puzzled when trying to locate his position, especially when he will do nothing but whisper, for this ventriloquistic effect is not so marked when singing loudly. Until pairing has taken place the song is almost incessant, morning and evening, rare during the daytime, more frequent at night; afterwards, and until the young are able to take care of themselves, it almost ceases, until it becomes a mere apology of the song of the mating season, often reduced to a few crackling notes, heard on a hot afternoon or during the first hour or so of dawn. To this partial cessation of the song may possibly be traced the belief that in certain districts the birds do not stop to breed, but are only to be found on their way to their breeding quarters; yet it is characteristic of many of the warblers, but perhaps more marked in the one under consideration; and thus the theory of the male lightening the female's task of incubation by song becomes a fanciful one, having little foundation of fact to recommend it, and against it the weighty evidence of Nature who always strives for a more complete concealment of her children. Before the arrival of the females, the males during the first few hours of daylight are very fond of playing with one another; and although their games are not to us very interesting, yet considerable energy is expended on them by the birds themselves. One male darts off after another one, pursuing him with very rapid flight into some thick bush; here he chases him up and down and along the branches with tail outspread and wings extended and slowly flapping, his behaviour being exactly similar to that during courtship, occasionally making use of a very curious note, much like the scolding of the Garden Warbler (Sylvia hortensis) when its nest is approached; and this sound appears to be produced with considerable exertion.
On the arrival of the females, about April 27th, ten days or so after the males, the courtship is immediately commenced. No period in the life-history of the individuals of any species is so interesting to watch or so full of significance as this. Every nerve is strained to a degree which makes incidents in 
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MALE GRASSHOPPER WARBLER.
ATTITUDE DURING COURTSHIP.
In referring to this period of the bird's life. I have used the simple term "courtship" instead of the usual display followed by selection. Fascinated by a picturesque theory, I have, previous to this, attempted to interpret facts accordingly instead of being ad utrumque paratios, but closer study, devoted for some years to this courtship, convinces me that sexual selection as a rational explanation of the phenomena is impossible: the following reasons have been mainly instrumental in forcing this conclusion upon me.
Selection is impossible unless there are two or more males to be selected from.
I can find no evidence of this being a general rule in Nature, for although a second male occasionally approaches the zone of courtship and is consequently chased away by the first male, yet he is in no sense a rival, making no attempt to perform in the same extravagant manner; and if these two males were in competition for the female, and if such competition were to be decided solely by her choice, then, not only ought they both to display their plumage, but, unless the female is to be credited with sufficient mental power to enable her to carry, for her further consideration, the varying characteristics of each male in her mind, such display ought to take place simultaneously.
This is by no means the case, for she is generally walking, "If the male assumes these attitudes in order that the female may see him to the best advantage and thus be enabled to make her choice, then she ought to be watching him when thus occupied."
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MALE GRASSHOPPER WARBLER,
ATTITUDE DURING COURTSHIP.
"Early in July a courtship, similar in every respect to the one in spring, occurs amongst the Sedge-Warblers."
Admitting the principle of selection, we must nolens volens assume this to be a selection taking place before the second brood, conclusively proving the choice of the female in the first instance to have been a mistake.
"The ultimate production of the most healthy and most beautiful offspring by the selection of certain males is, without a corresponding selection amongst the females, impossible, and of the existence of such selection in any form there is no evidence."
Individuals of both sexes vary very considerably both in intensity of colouring and actual quality of plumage. As an instance, the females of the present species are occasionally as rich in colouring as the finest males. Here, then, the impotency of sexual selection becomes apparent, for unless the females that choose the more beautiful males are themselves the more beautiful of the females, they will neutralise the effect of their own selection.
Although this is a truism which appears to me to be difficult to controvert, yet I must admit that we are here confronted with two difficulties, one an incomplete knowledge of the laws relating to heredity, the other an ignorance of the influence exerted by the female upon her embryo, which is profound. We do not even know whether heredity and this influence are distinct, or inseparable, merging into one another by very gradual stages. Yet this influence is a potent factor in all life, including man.[1]
Little importance need, however, be attached to these difficulties here, since they depend upon the supposition that characters acquired by one sex can be transmitted to that sex only. For instance, if the dull-coloured female Grasshopper-Warblers in a given area were to pair with the bright-coloured males, and the bright-coloured females with the dull-coloured males, the result in time would not be the continuation of these same conditions, but the gradual annihilation of the bright or the dull colours. It is inconceivable and contrary to the facts in Nature to suppose that the colouring of the female offspring could be in no degree influenced by the male parent, and vice versâ.
It has been suggested that the more vigorous females would be the first to breed, but this is a supposition made only to escape a difficulty, evidence in support of it being completely lacking: and since these same females vary individually very considerably in their colouring, we should at once, providing evidence were forthcoming in proof of 
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MALE GRASSHOPPER WARBLER,
ATTITUDE DURING COURTSHIP
Let us compare the courtship of the famous Argus Pheasant with that of any of the dull-coloured Warblers, for instance, Savi's Warbler (Locustella luscinioides). Here we have two cases, extreme as regards development of colour and shading, yet analogous in all other respects. The Argus Pheasant, when in presence of the female, spreads out and raises its tail and wings, the ocelli on the latter being thereby fully displayed; Savi's Warbler also under similar circumstances spreads out his tail and wings, the latter being very slowly waved up and down. These actions are identical, and evidently spring from the same cause, but no one can say that Savi's Warbler, in thus performing, has any special beauty to display. If, then, we say that the Argus Pheasant is conscious of the ocelli, of what is Savi's Warbler conscious? Clearly we are no more justified in imputing consciousness to the actions in the one case any more than we are in those of the other.
The courtship of birds presents many curious features; none more so than the spreading out of the wings and tail, commonly known as display, but these actions are not confined solely to courtship.
I have described the males of the species under consideration, both when playing with one another prior to the arrival of the females, and when feeding their fully fledged young, as behaving in an exactly similar manner. The male Chiffchaff, before the arrival of the female sometimes seems to be seized with a sudden ecstasy. He spreads his tail and jerks his wings, singing to himself quickly and quietly; also when a hawk approaches his breeding-quarters too closely he will fly into the air, slowly flapping his wings, and hurriedly singing in a similar manner to his courtship. I will give one other instance: The male Blackcaps, when excited with one another, or with another species, such as Sylvia hortensis, assume the same positions as when courting the females. To what do these facts point? Certainly not to a conscious display.
Further evidence, details of which I need not enter into here, prove that all these actions are intimately associated with the development and stimulation of the sexual organs.
When we come to consider all these facts, when, on the one hand, we find evidence of so strong a character opposed to the theory of sexual selection, and on the other, find that actions similar in every respect are frequently performed at other periods of great excitement in a bird's life, can we doubt the probability of their being solely reflex in kind?[2] I think not. All the difficulties would thus be removed, the second courtship of the Sedge-Warbler— a courtship which, although I have not hitherto seen it, yet in my opinion undoubtedly occurs amongst other species—is explained; and there would only remain the general argument, namely, that it is impossible to believe that all the trouble which many species apparently take with their courtship is purposeless: and this argument may be raised against the theory of reflex action; but because I exclude conscious choice from being in any way directly responsible for these actions. I by no means wish to imply that they are purposeless, neither am I prepared to enter into further explanation here, for I hold that with the very meagre knowledge that we, even at the present day, possess of all the facts relating to this most interesting subject, it would be unwise to attempt to formulate a theory in explanation of their ultimate purpose.
The peculiar manner in which these birds walk along 
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The nest, composed principally of dried grass interwoven with dead leaves and bracken, is, even when the young are hatched, most difficult to find. Placed sometimes almost on the ground, sometimes a few feet above it, it may be found in very different situations, such as in the centre of a clump of Juncus effusus, underneath a thick mass of the same rush overhanging a small watercourse, in the middle of clumps of long dead grass, and low down in thick gorse bushes. During incubation, which lasts about sixteen days, the female seldom leaves the nest. I once, in June, saw a pair playing with one another as it was getting light, between two and three o'clock in the morning; they were chasing one another, and the female settled and rested awhile on a branch quite close to me. When disturbed on her nest she will slip off quietly on to the ground and be quickly concealed, but if not too much alarmed will return, threading her way through the grass in the same stealthy manner. If lucky enough to find a nest with young, watch closely the parent birds; time thus spent will by no means be wasted. One nest. I remember, placed low down in a gorse bush, and in a great measure hidden by long grass, gave me an exceptional opportunity of doing this. The locality I found by luck, for, when walking close by, one of the parent birds was disturbed and flew out, but it was only with considerable difficulty that I found the actual nest. Crawling under the gorse and lying flat was useless, as one or other of the birds would walk within a few feet of my face and stare; to stand up seemed hopeless, but nevertheless it ultimately succeeded, and while I was remaining perfectly still, patiently enduring torments caused by insects, one of them, with a billful of food, went to the nest within a few feet of me. Upon my taking up the same position at daylight, the birds, losing a great deal of their fear, continued with the care of their young. In going to or leaving their nest they always ran, and so much do they resemble mice that I was once completely taken in, believing that what I saw was in reality a mouse. One of the parent birds once raised its wings in a threatening attitude, but this was the only occasion on which they showed any sign of objection to my presence. A note was frequently uttered by both sexes, but it seemed to me to be only a call-note to the young, probably to keep them quiet: the male sang at intervals very quietly, and the young, when being fed, uttered tiny squeaks.
When feeding the young they bring billfuls of insects, or to be more accurate, lumps of squashed insects, and by examining these lumps it is possible to find out what their food consists of. Wait until one approaches you on the way to the nest, then make a sudden movement or a step forward, and the food will in most cases be dropped. Their dexterity in collecting the insects is marvellous; even when their bill appears to be full they still continue darting at an aphis here and a gnat there, adding them to the lump, yet never dropping any of that already gathered, so quick are their movements.
The young leave the nest when only a few days old, and until able to fly are most difficult to find, concealed as they are in the dense undergrowth; but in the study of Nature it may with considerable truth be said that "all things come to him who waits." Having ascertained the position of a nest from which the young have only lately gone, go there soon after sunrise and get well hidden. You will hear the hum of insects commencing and gaining in strength, as in response to the intensifying rays of the sun each one begins his daily toil; you will hear an insect with a very small far-away squeak, which for a time will puzzle you, but since 
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GRASSHOPPER WARBLER
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; still, by waiting, and with head inclined first one way then another, noting the direction the sound appears to come from. I make up my mind as to the exact spot, divide the undergrowth with the greatest care, and am amazed to hear the squeak come from exactly behind me. If this is not ventriloquism I know not what else to call it; it is an even more effective deception than the adult birds are capable of. At this age the young have very few feathers, and their naturally long legs give them a rather clumsy appearance, but in reality they are capable of running quite fast, and to this fact, until an opportunity occurred of studying them more closely. I was inclined to partly attribute their ventriloquism; for when unconscious of being watched, they stand huddled up on the ground, their heads drawn close into their bodies, wings drooping, feathers loose and eyes half closed, and off and on they raise their heads for a moment, open their beaks and utter their little squeak, turning their head in expectation of food first one way then another, apparently unconscious of the ventriloquistic effect produced. The parent birds sometimes show very little solicitude for their offspring, even under the most trying circumstances; for when I have been sitting with a young one on my hand they silently came and peeped through the branches, disappeared for a moment, and looked again from the opposite direction, but made no sound, neither did they attempt in any way to entice me away. At other times when, attracted by the call. I have attempted to find the young, the female has shown considerable anxiety. She would utter a note which was a peremptory signal for the young to keep quiet, neither would any one of them, although scattered and a considerable distance apart, call again until she gave another signal; waiting for which signal considerable patience on my part was required, for the slightest movement would make her suspicious, hidden though she appeared to be, and when her suspicions were aroused she would immediately come up to the top of the gorse bush on which she was and watch my movements closely, nor were, her suspicions allayed until I had kept quiet for a considerable time. She seems herself to do all the feeding of the young after they have left the nest, the males leading a lazy life, singing and playing with one another. One instance, and this a curious one. I have seen of the male feeding the young when almost full grown. It was in a large field of clover, and I could find no sign of the female at all. The young were scattered considerably, and at intervals between the feeding the male sat on a post and sang. When actually feeding one of the young he would spread out his tail and wings and slowly wave them up and down. The young, when able to fly a little, occasionally come out of their hiding, but if pursued and made to fly they very soon get tired, and if driven into an open piece of ground, where there is no cover for them to conceal themselves in, they become completely lost. This I have proved by manœuvring them on to patches of burnt gorse: here they would run aimlessly about and make no attempt to conceal themselves.
I have once seen, on June 17th, two of the adult birds apparently on the point of pairing. The male was excitedly following the female, singing at intervals, and at times bowing slightly; but this is the only evidence I have that two broods may be reared in the same season, while on the other hand the general behaviour of the males, when the young are fully fledged, is very different to this, for they sing for about a fortnight, that is to say, during the latter part of June and the beginning of July, then become restless and wander away from their breeding quarters. During these last days of June, if the weather is warm, their song can be heard to advantage in the evening and on through the night, rising and falling as the head is inclined first this way and then that. It is surprising how the song will penetrate, for it can be heard without difficulty a quarter of a mile away. It often happens, too, at this time of year, that the only other sounds in the night-time are the "churring" of the Nightjar, the craking of the Landrail, and the hissing of the young Brown Owls, sounds which are well in keeping and only tend to emphasise the stillness of the night.
Although their song is so peculiar, yet there are a few notes in the song of the Tree-Pipit and Wren for which they may easily be mistaken, and often when listening at daybreak for these Warblers I have been completely deceived by these few notes, which, at a distance, with the remainder of the song lost, are barely distinguishable from those of the Wren or Tree-Pipit. The range of call-notes they use seems to be small; the usual one is something like that of the Robin or Blackcap, a "tic tac tac" and this note seems to be used principally when alarmed. The note which the female uses to call the male, or to put the young at their ease, is usually a single "tic" on the other hand, this single "tic" quickly and loudly uttered may also be one of alarm; it seems, therefore, that it depends more on the manner in which the note is given than on the actual note itself. There is no difference in the note of the two sexes.
Climatic conditions seem to influence them to a certain extent. In very wet weather they mope, and when in this frame of mind it is possible to approach them very closely and watch the vigorous attempts they make to dry themselves. There is also at certain times towards the end of June a cessation of their song for a few days, which, owing to its curious spontaneity, must. I think, be due to changes of weather. In cold frosty springs I have never been lucky enough to find sufficient nests to enable me to form an opinion as to the effect of frost on the eggs, so disastrous to those of many species.
These birds are entirely insectivorous, aphides in particular forming a great part of their diet; wood-lice, spiders, small moths belonging to the family Geometræ are also taken; I have also seen the males in June feeding upon the larvæ of Chimatobia brumata[3]. 
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- ↑ It is indeed difficult to understand the callousness with which this knowledge is treated in human life at the present day.
- ↑ In his "Last Words on Evolution," Professor Ernst Haeckel considers "sexual selection" of the greatest importance, both for the general theory of evolution and also for psychology, anthropology, and æsthetics. Since the importance of it is so great, no labour, surely, ought to have been spared to have verified the completeness of the fundamental evidence upon which it was originally based?
- ↑ The 'Winter Moth', now known as Operophtera brumata. (Wikisource contributor note)