Acknowledgments 



The observations on which I have based these studies were made 

 during expeditions for physiological investigations of adaptation 

 to the arctic Alaskan climate. These were supported by the Office of 

 Naval Eesearch, through the Arctic Research Laboratory, from 1947 

 to 1949 and by the United States Public Health Service, through the 

 Arctic Health Eesearch Center, after 1949. 



I am also grateful to the Arctic Institute of North America for a 

 grant, from funds provided by the Office of Naval Research, to assist 

 our biological reconnaissance at Old Crow in 1957, and for grants from 

 the Explorers Club in aid of the reconnaissance on the Ahlasuruk in 

 1953 and at Old Crow in 1957. 



Sig Wien, President of Wien Alaska Airways, whose many years 

 of arctic flying has brought him a thorough understanding of the fea- 

 tures of the country, and Thomas Brower of Barrow, whose keen un- 

 derstanding of life on the arctic coast had led him to suspect that 

 many birds reached there by migration through the mountains of the 

 Alaskan interior, were instrumental in leading me to choose the central 

 Brooks range as the key to the f aunal situation in arctic Alaska. 



Thomas P. Brower of Barrow, son of Charles Brower, also pointed 

 out to me the probable significance of the mountain passes as migra- 

 tory routes of the birds which he knows so well on the Arctic Coast 

 and related to me many pieces of information, sustaining that view, 

 derived from his own observations on the coast and accounts of Es- 

 kimo travelers in the interior. In 1949 he made extensive collections 

 and observations for me at Anaktuvuk which early presented an outline 

 of the migration. Since that time his friendly advice has repeatedly 

 helped to sustain my studies of arctic Alaskan animals. 



Since 1950 my colleague John Krog has joined me in physiological 

 studies of the effects of arctic temperature. I owe to him many long- 

 sustained observations, and I have gained from him many clear views 

 of arctic life which were supported by his vigor and skill in combining 

 experimentation in the field with studies in the laboratory. 



My colleague at Point Barrow, and later in Anchorage, Raymond 

 Hock, has given me much assistance from his observations at Tuluak 

 Lake during a few days in the spring of 1948, and from his observa- 

 tions on land and from the air in the lower Colville Valley during 

 that summer. 



VI 



