GARDINER'S ISLAND 49 



believe that they deliberately select such a position. Bather 

 it seems to me, these ground-dwelling birds, while inherit- 

 ing the nest building instincts of their species, are not in- 

 stinctively impelled to adopt a site which has proven to be 

 the most desirable for Fish Hawks. On the mainland, such 

 variability from the standard would have placed the bird, its 

 egg or its young within the reach of predaceous mammals, 

 and it doubtless would not have succeeded in rearing its 

 family. But in an environment where bird enemies are hap- 

 pily absent, the ground- building birds are as safe as those 

 nesting in the tree-tops, indeed, the ground- builders are in 

 less danger than the birds which build true to type, since the 

 trees to which, year after year, the birds come, may fall, 

 with consequent disaster to the nest. 



About ten pairs of Fish Hawks nest upon the ground, 

 and these ground nests are always placed on the beach. 

 Possibly the abundance of drift-wood may induce the birds 

 to select this situation. 



Several pairs of the beach-nesting birds have not only 

 failed to inherit the tree-nesting habit but evidently have 

 the nest-building instinct itself but slightly developed, their 

 eggs being laid on the ground with scarce a pretense of nest. 

 In most cases, however, the beach nests are large structures 

 containing two or three cartloads of sticks, their size being 

 dependent on their age, and the success with which they 

 weather winter winds and waves. I do not observe that the 

 number of beach nests has apparently increased since my 

 first visit to the island in 1900, from which we may infer 

 that the ground-nesting habit is not hereditary. 



As an intermediate site between ground and tree, some 

 Fish Hawks nest on large boulders either off-shore, when 

 the birds have an island of their own, or inland on the roll- 

 ing plains. One pair of birds had nested for many years on 

 the roof of a small ' ' yoke-house ' ' standing in a field which, 

 when I first saw it on May 30, 1900, was green with young 

 rye. The house itself offered the only available concealment 



