480 ANNUAL REPOKT SMITHSONIAN INSTITUTION, 1917. 



beak and the food is allowed to fall to the ground, it is ludicrous to watch the 

 rapidity with which the parent picks up the food and reswallows it. Often- 

 times the mate of the feeding parent is near ; its role is a purely passive one 

 except when the " spectators " attempt to approach too near. Its part is then to 

 assist in warding them off. * * * 



The parents alternately feed the young, but instead of a diurnal period of 

 feeding, such as the parents have before the appearance of the young, the inter- 

 vals vary anywhere from four to seven hours. * * * 



The care of the young, especially from 20 days on, must be an exhausting 

 process for the parents. They become emaciated and somewhat bedraggled 

 in appearance. This is not to be wondered at when we consider that a healthy 

 young sooty can eat anywhere from 20 to 40 minnows of no insignificant size 

 in a day. It may be of general interest to note that after the first few days 

 the parent always recognizes and feeds its own young and no others, and fur- 

 thermore, the young tern recognizes its own parents and attempts to feed only 

 from them. Never but once out of many thousands of observations did I see a 

 young tern begging food from a stranger. 



Watson and Lashley have shown conclusively by a large series of 

 experiments that the sooty tern seems to entertain man's legal aspect 

 of property rights. 



Many attempts were made to shift nests to the edge of the beach with the 

 purpose of transferring them to rafts in the hope of ultimately transplanting a 

 part of the colony to other keys, but however slowly such shifts were made 

 (6 inches or so per day) the nests were either abandoned when moved 4 feet 

 or less from their original position, or the eggs were rolled back as fast as they 

 could be moved forward. 



On the other hand, a vertical elevation of the nest to a considerable 

 height did not cause its abandonment, as shown by the following 

 experiment made by Watson : 



A nest was chosen in an open space, but very close to some bushes. I ob- 

 literated the nest as the bird had constructed it, inserted a black pan, filled 

 this with sand, and constructed a nest inside of it. This gave me an oppor- 

 tunity to move the nest upward as well as laterally. On returning, the bird 

 alighted on the nest without showing any signs of disturbance. An hour later 

 I came back and pulled the pan out of the sand and put a few sticks under it. 

 The bird returned, but was not disturbed by this slight change. I then drove 

 in four stakes 10 centimeters high and mounted the pan thereon. This served 

 to raise the nest upward without disturbing the other relations of the nest. 

 The bird on returning alighted immediately on nest. The other birds gathered 

 around, craning their necks and peering upward. The bird then stood up and 

 came to the edge of the pan and peered down. This seemed to disturb it and 

 it flew to the ground, but hopped up again immediately, covered the egg and 

 sat there in comfort the rest of the day. Raising the nest 10 centimeters in 

 the air requires almost no adjustment on the part of the bird. On account 

 of a storm on the island, which lasted for two days, no further experiments 

 were made at this time on this nest. I next raised this nest 100 centimeters ; 

 bird alighted immediately squarely on the top of the nest; did not make a false 

 movement. On craning neck over the edge of the pan a little later, however, 

 became disturbed and alighted on the ground, and remained there for 45 min- 

 utes without attempting again to get on nest. I forced the bird to fly up. Again 



