400 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1958 
when the tide is low at night, they haul out at favorite spots to sleep. 
Mothers with young frequently bring their pups ashore about sun- 
down to remain on the rocks until daybreak. 
In the Aleutians at least, the breeding season is not well defined. 
Newly born pups appeared as numerous in early December of 1957 
as they had been in the spring and summer of previous years. Pres- 
ent indications are, as early sea otter hunters reported, that breeding 
is continuous throughout the year. Mating takes place in the water 
and the mated pair may remain together for several days. During 
this period they make food dives side by side. They also choose a 
favorite rock where they haul out in close company to sleep and 
preen between feeding periods. This postmating association is ap- 
parently more desired by the male than the female. Since a male 
appears to require more food than the female, he sometimes leaves 
the resting rock to dive for food nearby, while the female remains 
behind to preen. In several instances I watched the female quietly 
slip into the water and leave her mate while he was beneath the sur- 
face. On discovering her absence, the male became quite excited 
and began a systematic search of all likely rocks, rising half out of 
the water to look onto them or actually climbing up to search their 
tops. In the cases I observed, the female was successful in eluding 
her mate. 
Like other marine mammals the sea otter bears but one pup at a 
time, but, unlike most of them, the mother otter gives her offspring 
constant and careful attention over a relatively long period, probably 
until it is nearly a year old. For several months the pup receives 
most of its nourishment from its mother’s two abdominal nipples, 
though at an early age it may also beg for and receive parts of sea 
urchins and mollusks that its mother is eating. She carries her pup 
on her chest while she herself swims on her back. On this floating 
platform the pup nurses, sleeps, and receives almost constant preening 
from its mother’s mobile and sensitive forepaws. The mother leaves 
her pup only when she dives for food and a food dive seldom lasts 
more than a minute. While the mother is below the surface the pup 
usually sleeps, buoyed up by the air enclosed in its long, clean, dry 
fur. After each such dive the mother swims to her pup’s side, where 
she eats the food that she has carried to the surface enclosed by a fore- 
leg and a fold of loose skin across her chest. If her pup has drifted 
with the wind, she takes it onto her chest and returns it to the area 
in which she wishes to feed. 
Sea otter pups are playful and, if a mother is feeding near sheltered 
kelp-covered rocks, the pup will often play in the gentle surge among 
the slippery strands. Once I watched a pup working its way around 
the rocks until it was hidden from its mother’s view. Suddenly it 
missed her and uttered a harsh, frightened cry. Confused by the echo 
