20 



NORTH AMERICAN FAUNA 68 



NEWBORN YOUNG 



The data on body size of the youngest sea otters obtained are 

 reported in table 1. The umbilical scar was fresh on each indi- 

 vidual listed and all showed little or no wear of the fetal claw 

 tips (fig. 13). The two smallest, a male weighing 2.6 lb. (1.2 kg.) 

 and a female weighing 2.25 lb. (1.02 kg.), were both dead when 

 obtained, one from the beach and the other from a mother that 

 was netted on the beach while carrying her dead pup. Among 

 the seven largest fetuses (four males and three females), collected 

 at Amchitka in 1963, the largest, a male, weighed 4.12 lb. (1.869 

 kg.) and measured 61.0 cm. in length. The mean weight was 3.5 

 lb. (1.598 kg.) and the mean length 57.3 cm. (22.5 in.). Thus it is 

 probable that the two smallest newborn young were stillborn, 

 being abnormally small at birth. All of the others had received 

 at least some nourishment in the form of milk from their mothers 

 before capture, thus were heavier than when newly born. The 

 living young examined indicate that a healthy newly born sea otter 

 may weigh as little as 3 lb. (1.4 kg.). But the fetal material studied 

 (see Reproduction in the Female) and larger newborn young indi- 

 cate that larger body size of 4.12 lb. (1.869 kg.) to 5 lb. (2.3 kg.) 

 and 61 cm. (24 in.) in total body length is probably normal. 



ADULTS 



Analysis of the weights and lengths of 84 adult males and 258 

 adult females that were shot, are given in tables 2 and 3. Animals 



Table 1. — Weight and length of newborn pups taken at Amchitka Island, 



Alaska 



[The umbilical scar or adhering fragments of the umbilical cord were fresh. All except the two 

 dead pups contained small quantities of milk] 



Collection number 



Date 



Weight 



Length 







Kg. 



Cm. 



Males: 











. 29 March 1955 



1.6 



58.0 



32-56 1 



26 May 1956 



1.2 



47.3 



D-6-57 



18 November 1957 



2.5 



62.9 



62-178 



18 February 1962 



1.7 



52.8 



Mean 





1.75 



55.25 



Females : 









32-56 2 



25 May 1956 



1.02 



48.4 



D-2-57 



11 October 1957 



1.45 



52.1 



D-15-57- . 



16 October 1957 



2.4 





(3) . 



15 Apr. 1959 



1.7 





60-1 7 _- 



8 July 1960 



2.35 



"53^ 



60-21 



10 July 1960 



2.83 



61.6 



Mean 





1.96 



53.9 



1 Freshly dead pup taken from the mother when she was netted. 



2 Freshly dead pup found on beach. 



3 Mother and pup netted and released. The pup was not tagged because it was obviously new- 

 born (umbilicus still attached and fresh). 



