228 



NORTH AMERICAN FAUNA 68 



Table 51. — Reproductive status of adult nonpregnant sea otters 



[Nine animals, adult in body size but being- nuUiparous and showing no follicular activity, are 



excluded] 



Samples collected in — 



Summer Fall, 1957 



Spring 1963, 1963.i and 1962, 



Mar.-Apr. July-Aug. Oct.-Nov. 



Nonpregnant Num- Per- Num- Per- Num- Per- 



tracts ber cent ber cent ber cent Total 



Postpartum, inactive ovaries: 



Pup present 13 35 8 61 21 



Pup absent 16 43 3 60 1 8 20 



Inactive ovaries 2 4 11 2 40 3 23 9 



Active ovaries ^ 4 11 18 5 



Total 37 100 5 100 13 100 55 



Total tracts examined and percent 



not pregnant 125 30 14 36 17 76 156 



1 Animals were killed selectively to exclude all mothers accompanied by young. The objective 

 was to take as many male skins as possible in a female area. Among 19 independent animals, 

 only 1 male was taken. 



2 Multiparous but not showing positive evidence of being recently postpartum. 

 ^ Estrus and proestrus. 



total numbers of specimens are shown because not all specimens 

 could be used for every aspect of this study. I did not examine all 

 collections and samples. Those that I did examine presented ade- 

 quate information for certain aspects of this study. 



The reproductive tracts were removed from the animals from a 

 few minutes to several hours after death, depending on field con- 

 ditions. They were then fixed entire for 24 hours in AFA solution 

 (95 percent alcohol, 30 percent; commercial formalin, 10 percent; 

 glacial acetic acid, 10 percent; water, 50 percent). After fixing, the 

 tracts were stored for later study in 70 percent isopropyl alcohol. 



Sinha et al (1966) explain how^ certain aspects of reproductive 

 tract studies were conducted. I examined ovaries with a lOX Loupe 

 after slicing them into sections about 1 mm. in width. 



FIELD COUNTS OF SEA OTTERS 



Field counts of sea otters were recorded whenever possible. The 

 primary objectives were to obtain information on (1) the season 

 of birth, and (2) the annual rate of reproduction. 



Observations were limited by: (1) Environmental conditions 

 such as wind, precipitation, and rough water ; (2) a variable degree 

 of sexual segregation among independent animals, including 

 mothers with young; (3) the often indistinguishability of sexes 

 and age classes; and (4) the constant movement of animals to and 

 from local areas. In spite of these factors, useful field observations 

 were obtained. 



