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Show 1869.] HABITS OF THE HORNBILLS* 145 the keepers and others who are known to him. The male Concave Hornbill (Buceros cavalus) now in the Gardens will frequently throw up grapes and, holding them in the point of the bill, thrust them into the mouth of the keeper if he is not on the alert to prevent or avoid this distinguished mark of his kindness. W e have now to consider the facts brought forward; and in no class of animals do we find so many instances of the frequent and easy mode of casting up or reproducing the food, or iu other cases the indigestible substances taken with the food, as in Birds. But there is more than this to be noticed; for instance, in the Esculent Swallows. W e know the so-called edible Swallow's-nest consists of a gelatinous secretion from the glands of a kind of Swift; and doubtless a portion only is used to form the nest; the secretion is, in all probability, continued to feed the female aud young, probably mixed with the insects captured during flight. There is also a similar secretion from the Woodpecker, but in this case made to assist in the capture of their food; and many other instances can, no doubt, be brought forward, showing the power that birds have of ridding their stomachs of that part of their food not required for their nourishment. One very remarkable instance I well remember. A year or two ago I found in m y garden, in a small heap, about a handful of the most beautiful blue pills, about the size of peas and studded all over with brilliant and shining blue fragments. I soon discovered that they were the castings of the Flycatchers that had a nest immediately above the spot upon which I found them; the charming colour was due to the outer skins of the Bluebottle flies upon which the birds had fed. All the insect-feeding birds throw up pellets consisting of the refuse or indigestible parts of the insects they swallow, just in the same way as the Raptorial birds (as Hawks, Owls, &c.) cast up the feathers, bones, hair, and food of grain-eating animals iu the form known as castings or pellets. In conclusion, I think I may fairly reason that it is much more likely that these food-pellets of the male Hornbill are intended for the support of the female and young, and belong to the natural and healthy condition of the birds which produce them, than that they are the result of indigestion or disease. For we see that the power and habit of casting up from the stomach is one of frequent and common occurrence among birds, and also find that the secretions of the oesophagus are used as food for the young of many species of birds: in the Parrots and Pigeons I think this is universal. Another strong argument in favour of m y belief is to be found in Dr. Livingstone's statement that " the male bird by his constant attention upon the female becomes so prostrate and exhausted that a slight change in the temperature causes him to fall down and die." It cannot be supposed that the mere collecting food for the female is the cause of this fatality ; it is doubtless the overtaxing the system bv the constant secretion of this nutritive miatter, reminding one of the blood in the nests of the Esculent Swifts after the birds have been robbed of the first and second nests. But the most positive proof of finding this package of food is given, without, however, under- PROC. ZOOL. Soc-1869, No. X. |
