114 Adams, Ecological Succession of Birds. [\tlril 



as well as those of habitats just cited, and for this reason it is 

 necessary not to confuse such variations with those confined to 

 some restricted area. These local and geographic relations are 

 very intimately related, but they are subjects which can only be 

 worked out in detail when local studies give proper attention to 

 local environmental responses. 



In the following account of the literature no attempt is made at 

 completeness, but the papers cited are believed to be representative. 

 These papers will help to give some idea of the kind of observations 

 and records already made, and will be suggestive as to future work. 

 ]\Iention will first be made of the literature on habitat preference, 

 and then of that on succession. 



By far the best discussion we have found on habitat preference of 

 the birds of a given region is that by Townsend ('05) on Essex 

 County, Massachusetts. The primary avian environments are 

 described, the representative birds listed, and their preferred habi- 

 tats are briefly discussed. Thus, the ocean and its birds, the sand 

 beach and its birds, the sand dunes and their birds, the salt marshes 

 and their birds, and the fresh marshes and their birds, give a general 

 idea of the subjects treated. Regarding the birds of the sand 

 beaches, he remarks: "Among the Plover, the Black-bellied, Semi- 

 palmated, and Piping Plovers are above all birds of the beach, 

 although the first two are occasionally found in the marshes, while 

 the last-named rarely strays from the beach and the adjoining sand 

 dunes. The Golden Plover, although at times found on the wet 

 sands, is much more likely to hunt for food on the dry sands above 

 the highest tides, or still farther inland, while the Killdeer generally 

 avoids the beach altogether, preferring the fields" (p. 21). And 

 regarding the birds of the sand dunes he remarks: "Savanna 

 Sparrows nest in numbers at the foot of clumps of tall beach grass 

 throughout the dunes, and on the edges of the tidal inlets from the 

 marsh. The nests of the Red-winged Blackbirds and the Bronzed 

 Grackles are abundant in the bogs and groves of the birches. The 

 Crow, in the absence of tall trees, builds perforce in the stunted 

 pines and birches, at times only ten or twelve feet from the ground " 

 (p. 34). In the case of the Crow, note that he records the response 

 to the dune en\aronment. 



While Townsend recognizes changes in the environment, as in the 



