48 



and their adaptations to this habitat are, at best, obscure. 

 By an intensive study of these birds and the factors of the 

 environment in which they Hve, it is hoped to gain some dej&- 

 nite knowledge of the processes which are ever present, 

 moulding their actions, shaping structure to habit and habit 

 to structure — processes which have exterminated whole races 

 of birds in the past and which even to-day are creating new 

 ones. 



PART I. THE ENVIRONMENT. 



In beginning investigations of this kind, the first requisite 

 is an intimate knowledge of the environment to be considered 

 — a knowledge which cannot be gained by a few months of 

 casual observation, but which requires years of intensive 

 study. The discussion which follows is but a brief outline of 

 the facts that ought to be known. 



Geographically, the tract under consideration, known as 

 Renwick Marsh,* is situated in the central part of New York 

 State at the head of Cayuga Lake. Its latitude is 42° 27' 

 north, its longitude, 76° 29' west. The marsh proper covers 

 approximately 450 acres and is almost at lake level, its altitude 

 being 383 feet. Concerning the ancient history of Cayuga 

 Lake or the "Finger Lakes" in general, little need be said 

 here. They represent preglacial river valleys, widened and 

 deepened by the action of the ice, and left in most places with 

 rather precipitous shores. As a result, the marsh is sheltered 

 on the east and on the west by hills which rise about 400 feet 

 in the first half mile, and reach an altitude of 1,400 or 1,500 feet 

 within five miles. Physiographically, the marsh represents a 

 delta formed by the streams that flow into the lake at its south- 

 ern end — Cayuga Inlet, Fall Creek, and Cascadilla Creek. The 

 marsh probably originated from the stagnation of the waters 

 behind a bar that was formed across the head of the lake by 

 the action of northerly winds and the lateral tributaries, 



* Since the completion of this study, dredging operations for the Barge 

 Canal, resulting in the deepening and widening of the Inlet, and the con- 

 sequent filling on each side, have almost completely destroyed the marsh 

 and replaced it with extensive, dry, sandy flats of little ornithological 

 interest. 



