The Tortugas Tern Colony 81
of the crop will be deposited on the rim of the nest and this will be eaten by the female.
The young are fed by both parents upon food disgorged in a similar manner. They are among the most helpless of young wild birds. being absolutely dependent upon their parents for food until they are over three months old,
For the first two months they remain in the nest: after that they are in and out of it, resting near by on branches. and when frightened de- scending to the ground and seeking shelter among the roots and in neighboring tufts of grass.
It is a rather humorous sight to see one of theSe great over- grown babies with an adult appetite patiently waiting for meals to be brought and scolding vigorously when the supply has given out. They are fully four-fifths the size of the adult before competent to care for themselves.
Normally but one egg is laid by a pair. but if it is injured or lost its place is promptly taken by another. One of the nests, during a storm. was broken. and the egg, then two weeks old, rolled into such a posi» tion that it was impossible for the birds to get at it. The following day the birds built a superstructure to the nest. and within a week another egg was laid, and their housekeeping proceeded without further interruptions,
This ability to control the size of the family presents a physiological I 0" 500'"
problem of great interest. Normally. it consists of one young; bUt the possible number is apparently very large, as the same nest can be robbed many times of its egg and yet another will be deposited.
Another fact of great interest is the psychological change in the birds' characters as evidenced by their attitude toward man during the breed* ing season. These birds live on the high sea two-thirds of the year. and then are not easy to obtain with a shot-gun; hut. when brooding, the mother-bird can be approached and easily taken in the hand. Toward the end of the season they can be picked up and handled. and when
