Sea otter. — During the year work was conducted 

 in six general areas of the sea-otter range, requir- 

 ing several thousand mfles of flight. A total of 

 nearly 11,000 sea otters were observed by the per- 

 sonnel assigned. Much additional time was given 

 to study of specimens, analysis of data, and prepa- 

 ration for publication of all material on the sea 

 otter in Bureau files. 



Marten. — For several years the Montana Unit 

 studied the breeding physiology of the pine marten 

 under the direction of Dr. P. L. Wright of Mon- 

 tana State University. The Anaconda Creek 

 population under observation showed evidence of 

 recovery after declining from a peak in 1953-54. 

 These fluctuations coincided roughly with a small- 



mammal peak ill 1953, a low in 1955, and return to 

 high density level in 1957 and 1958. 



More general studies by the Colorado Unit dis- 

 closed indications of fluctuations in marten num- 

 bei-s, and veiy definite cyclic behavior in several 

 genei'a of mice. Marten numbers are considered 

 relatively high in this State at the present time. 



Fisher. — The Maine Unit is now completing a 

 9-year investigation of the fisher, and results are 

 being used in a doctoria) dissertation by Malcolm 

 W. Coulter, who conducted the primary study. 

 This "wilderness" fur animal has demonstrated 

 pronounced adaptability to habitat variations in 

 its recent and widespread extension of range in the 

 upper Northeast States and Provinces. 



Dog team waitinp for its trapper owner to return from checking a trap. A mink and snow^ owl are shown on the 

 sled. Travel incident to the Alaska Unit's study of mink in the Yukon-Kuskokwim Delta. (Photo by John J. 

 Burns) 



34 



