The terns which breed on islets in Indian rivers do not appear to do much incubating in the daytime. There is no need for them to do so, because the sand grows very warm under the rays of the sun. Moreover, the only foes to be feared are the crows and the kites, which the terns can keep at bay more effectually when on the wing than while sitting on the eggs. Very different is the behaviour of the sea terns, whose eggs are liable to attack by gulls and crabs. For safety’s sake the sea terns lay in large colonies, and, to use Colonel Butler’s expression, sit on their eggs “packed together as close as possible without, perhaps, actually touching one another.” He once came upon the nests of a colony of large-crested terns (Sterna bergii). The sitting birds did not leave their eggs until he was within a few yards of them. Having put them up, he retired to a little distance. “No sooner had I done so,” he writes, “than both species [i.e. the gulls and terns] began to descend in dozens to the spot where the eggs were lying. In a moment a general fight commenced, and it was at once evident that the eggs belonged to Sterna bergii, and that the gulls were carrying them off and swallowing their contents as fast as they could devour them.” River terns do not construct any nest. They deposit their eggs on the bare, dry sand. The eggs have a stone-coloured ground, sometimes suffused with pink, blotched with dark patches, those at the surface of the shell having a sepia hue, and those deeper down appearing dark greyish mauve. The eggs, although not conspicuous, may, without difficulty, be detected when lying on the sand. Their colouring would seem to be adapted to match a stony, rather than a sandy environment, but the fact that the colouring of the eggs is but imperfectly protective does not much matter when the latter lie on a sand island, to which but few predaceous creatures have access; the watchfulness of the parent birds more than compensates for the comparative conspicuousness of the eggs.
Young terns, like most other birds, are born helpless, and are then covered with a greyish down; but before the tail feathers have broken through their sheaths, and while the wing feathers are quite rudimentary, the ternlets learn to run about and swim upon the water. At this stage the little terns look like ducklings when on the water, and, as they run along the water’s edge, may easily be mistaken, at a little distance, for sandpipers.
When a young tern is surprised by some enemy, his natural instinct is to crouch down, half buried in the sand, and to remain there quite motionless until the danger has passed. The colouring of his down is such as to cause him to assimilate more closely to the sandy environment than the eggs do. If one picks up such a crouching ternlet, the bird will probably not struggle at all; it may, perhaps, peck at one’s fingers, but in nine cases out of ten will remain limp and motionless in the hand, looking as though it were dead, and if it be set upon the ground it falls all of a heap, and remains motionless in the position it assumed when dropped. If you take a young tern in your hand and lay it upon its back on the sand it makes no attempt to right itself, but remains motionless in that attitude, looking for all the world like a trussed chicken; but if you turn your back upon it, it will take to its little legs and run, with considerable speed, to the water, to which it takes just as a duck does, its feet being webbed at all stages of its existence.
XXI
GREEN BULBULS
Since green is a splendid protective colour for an arboreal creature, it is surprising that there are not more green animals in existence. The truth of the matter is that green seems to be a difficult colour to acquire. There does not exist a really green mammal; while green birds are relatively few and far between. In India we have, it is true, the green parrots, the barbets, the green pigeons, the green bulbuls, and the bee-eaters. Take away these and you can count the remaining green birds on the fingers of your hands. Curiously enough, the bee-eaters spend very little time in trees; consequently the beautiful leaf-green livery seems rather wasted on them. And of the other green birds we may almost say that they are precisely those that seem least in need of this form of protection. The parrakeets and barbets, thanks to their powerful beaks, are well adapted to fighting, while more pugnacious birds than bulbuls and pigeons do not exist. I think, therefore, that the green liveries of these birds are not the result of their necessity for protection from raptorial foes. This livery is a luxury rather than a necessity.
Anatomically speaking, green bulbuls are not bulbuls at all. Jerdon called them bulbuls because of their bulbul-like habits, although, as “Eha” points out, they take more after the orioles. Oates tells us that these beautiful birds are glorified babblers, rich relations of the disreputable-looking seven sisters. He gives them the name Chloropsis.
Seven species of green bulbul are found in India; they thus furnish an excellent example of a bird dividing up into a number of local races. When the various portions of a species become separated from one another this phenomenon often occurs. The common grey parrot of Africa is, according to Sir Harry Johnston, even now splitting up into a number of local races. That interesting bird is presenting us with an example of evolution while you wait. It is quite likely that the process may continue until several distinct species are formed. We must bear in mind that there is no essential difference between a species and a race. When the differences between two birds are slight we speak of the latter as forming two races; when the divergence becomes more marked we call them species. Very often systematists are divided as to whether two allied forms are separate species or mere races. In such cases some peacemakers split the difference and call them sub-species.
Green bulbuls are essentially arboreal birds. In the olden time when India was densely wooded I believe that there was but one species of Chloropsis, even as there is but one species of house-crow in India proper. Then, as the land began to be denuded of forest in parts, these green bulbuls became a number of isolated communities, with the result that they eventually evolved into several species. In this connection I may mention that the grey on the neck of Corvus splendens is much more marked in birds from the Punjab than in those that worry the inhabitants of Madras.
Of the green bulbuls only two species occur in South India—the Malabar Chloropsis (C. malabarica) and Jerdon’s Chloropsis (C. Jerdoni). The former, as its name tells us, is found in Malabar. The green bulbul of the other parts of South India is Jerdon’s form. This handsome bird does not occur in or about the City of Madras; at least I have never seen it in the neighbourhood, nor indeed nearer than Yercaud. However, not improbably it occurs between the Shevaroys and the east coast. If anyone who reads these lines has seen this bird in that area, I hope that he or she will be kind enough to let me know. Here let me say that to identify a green bulbul is as easy as falling out of a tree. He is of the same size as the common bulbul. His prevailing hue is a rich bright grass-green—the green of grass at its best. His chin and throat are black, and he has a hyacinth-blue moustache, so that he deserves his Telugu name—the “Ornament of the Forest.” His wife is pale green where he is black and her moustache is of a paler blue. The Malabar species is easily distinguished by its bright orange forehead. Green bulbuls go about, sometimes in small flocks, more frequently in pairs. They rarely, if ever, descend to the ground, but flit about amid the foliage, to which they assimilate so closely, seeking for the insects, fruit, and seed on which they feed. Like many other gaily attired birds, they give the lie to the oft-repeated assertion that it is only the dull-hued birds that are good songsters. Green bulbuls are veritable gramophones, “flagrant plagiarists” Mr. W. H. Hudson would call them. Not only have they a number of pretty notes of their own, but the feathered creature whose song they cannot imitate remains yet to be discovered. Green bulbuls might be called Indian mocking-birds were there not so many other birds in the country that imitate the calls of their fellows. Some ornithologist with a good ear for music should draw up a list of all our Indian birds that mock the calls of others, setting against each the names of these whose sounds they imitate.
Green bulbuls are hardy birds and thrive well in captivity. I saw recently a specimen in splendid condition at a bird show in London. “There is one drawback, however,” writes Finn in his Garden and Aviary Birds of India, “to this lovely bird (from a fancier’s point of view), and that is its very savage temper in some cases. In the wild state Mr. E. C. Stuart Baker has seen two of these birds fight to death, and another couple defy law and order by hustling a king-crow, of all birds. And in confinement it is difficult to get two to live together; while some specimens are perfectly impossible companions for other small birds, savagely driving them about and not allowing them to feed. Many individuals, however, are quite peaceable with other birds, and a true pair will live together in harmony.”