Bird studies with a camera

by Frank M. Chapman

Incubation was found to be well advanced in eggs which were alone in their nest, showing either that one egg sometimes composes the set, or that the other eggs of the set had been destroyed. The fact that one nest was found with three young while twenty-three were found each containing three eggs, would indicate a high mortality among the young birds; and, indeed, no less than 94 dead young were counted. Most of these, however, were birds which were old enough to leave the nest, and death was doubtless due to the thoughtlessness of tourist visitors, who chase the young about until they fall from exhaustion, or are driven too far to find their way home.

Estimating the number of young birds which had left the 594 deserted nests at 891—which would be an average of one and a half birds to the nest—and adding two parent birds to each nest, we have 2,581 birds on wing and on foot. But this number is to be increased by the 152 young that were still in their nests, making the probable total population of Pelican Island 2,736. This calculation, however, does not take into account the eggs, from which almost hourly came new inhabitants of the island; and it is with these eggs, or rather with the nest in which they are placed, that we may begin a brief outline of the young Pelican’s development.

The Pelican, although a low type of bird, is altricial, the young, unlike the offspring of Gulls, Ducks, or Snipe, being hatched in a helpless condition. The nest, therefore, is not only an incubator where with heat from the parent bird the eggs are hatched, but it is a cradle for the young. Consequently, Pelicans’ nests are unusually complicated structures as compared with the dwellings of other birds equally low in the evolutionary scale.

There was a very interesting and constant relation between the character of the nest and its site, ground nests being composed largely or entirely of long grasses, while those nests which were placed in the trees were made of sticks and were lined with grasses, the nest proper being erected on a platform of larger sticks laid from crotch to crotch in the bushes in such a manner as to form a broad, firm foundation, though, structurally, it was not a part of the nest, which could be lifted without removing the platform.

106. Newly hatched Pelicans. Ground nest.

The difference between the nests of straw^[106] and those of sticks^[107] were so marked that it seems probable their makers regularly selected sites on the ground or in the trees respectively. Or, assuming that the same individuals might build a stick nest in the bushes one year and a straw nest on the ground the next, we have an unusual variation in the character of the nest of the same species. In the case of the Fish Hawks of Plumb Island the birds evinced an appreciation of the protection afforded them by the owner of the island by often placing their nests on the ground. Photographs of these nests, however, made by Dr. C. S. Allen, show that the birds employed as much material when nesting on the ground as when nesting in trees, the eggs on the ground being surrounded by a useless mass of large sticks. Certain of the birds, therefore, in response to new conditions, had chosen new nesting sites, but had not as yet made corresponding changes in the character of their nests.

When the nest is completed, as we have seen, from one to three eggs are laid. The period of incubation is probably about four weeks, and a careful listener may detect the presence of a hatching egg by the choking bark which the young Pelican begins to utter as soon as he has made an opening in the shell which holds him. When he has finally freed himself and appears in the world, he is about as unattractive a bit of bird life as can well be conceived.^[106] His dark, purple skin is perfectly naked, he is blind, and when he is deprived of shade provided by the brooding parent, he twists restlessly about in the nest, uttering the same choking bark with which he first greeted the light.

Even at this early age he displays one of the strong characteristics of the immature Pelican—a pugnacious disposition. Almost before his eyes are open he bites at his nest mates for apparently no other reason than that they come within reach of his bill. Soon his eyes open and within a few days a wonderful change begins to take place in his appearance.^[107] Little bunches of white down sprout all over his body, and, growing rapidly, transform the ugly, purple-black nestling into a snowy creature clad in softest down.