254 FRANCIS H. HERRICK 



munity into panic, when they would ascend to a great height, 

 or leave the island until peace was restored. 



In any event, building their nests in trees, as a few now do 

 at a common height of from six to ten feet, could have afforded 

 them no protection from man, and probably none from their 

 one other inveterate enemy, without their own ranks, the crow, 

 which still harries their nurseries at will. 



A census of loo nests of this gull, taken at random, was made 

 on the island July 17, 1902, and in regard to position gave the 

 following results: 



Ground nests, often placed under dead spruce 89 



Tree nests in upright spruce, either living or dead, 1 to 9 feet 6 



Rock nests, on ledges, and usually nearer the sea 2 



Nests on logs or fallen trees 3 



100 



Had this survey been made on the confines of the colonv 

 the number of nests placed on bare rocks would have been 

 greater, but so far as trees are concerned the results would 

 have been essentially the same. 



In relation to tree nesting another question must be con- 

 sidered, and that is the restrictions imposed upon the young, 

 especially when their nests are at a considerable height. As 

 I have shown in an earlier paper " the gull community is organ- 

 ized on a peculiar basis, and this is particularly important in 

 such crowded communities as found at Great Duck. Each pair 

 of birds discriminates their own chicks with precision, and guards 

 the territory or preserve on which are placed their nest, cover 

 for the young, perches and feeding spots, with the utmost 

 vigilance. Trespassing adults are fought off, and straying chicks 

 are quickly struck down and often killed in cold blood, unless 

 protected by their parents. The admirable guarding instinct 

 is thus the cause of many untimely deaths in every community, 

 and numbers of recently slain birds of all sizes can be seen any 

 day upon the breeding grounds. Now nesting in trees would 

 undoubtedly tend to check the errors of instinct in permitting 

 the too early or too indiscriminate straying of the young, and 

 thus be a source of protection. Without any doubt young are 

 liable to fall out of the nests when close to the ground, but at 



'^ Organization of the Gull Community. Proceedings of the Seventh Inter- 

 national Zoological Congress. Cambridge, 1909. 



