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Item Description Miller, Edward H. en_US 2008-03-21T01:45:32Z 2008-03-21T01:45:32Z 1975-04 en_US
dc.identifier.citation Miller EH. 1975. Annual cycle of fur seals, Arctocephalus forsteri (Lesson), on the Open Bay Islands, New Zealand. Pac Sci 29(2): 139-152. en_US
dc.identifier.issn 0030-8870 en_US
dc.description.abstract Fur seals, Arctocephalus forsteri (Lesson), were studied on the Open Bay Islands, South Island, New Zealand in 1970-1971. Few adult males were present at the colony site during the winter, but many arrived ashore in November to vie for territories. Individual territorial males remained ashore and fasted for up to 63 days before losing or abandoning their territories. A few adult males reappeared briefly at the colony site a few weeks after abandoning their territories, and left again. Subadult males were common at the colony and other parts of the Open Bay Islands at the start of the breeding season, but their numbers declined steadily throughout it. Adult females frequented the colony site throughout the year. Some pregnant females appeared some weeks before parturition in areas where they subsequently gave birth, then left to feed. The tendency of pregnant females to feed heavily in the weeks prior to giving birth resulted in few females being ashore in mid-November. Pregnant females landed ashore about 2.1 days before parturition. After having given birth, they remained ashore with their pup for about 8.8 more days before leaving to feed. Parturient females entered estrus and copulated about 7.9 days postpartum; sexual receptivity was observed to last up to 14 hrs. Parturient females were absent for about 4.4 days on their first feeding trip after having given birth, and were ashore with their pups for about 2.8 days immediately thereafter. Subsequent feeding periods at sea were longer. Mothers nursed their pups for about one-third of the time that the former were ashore. The fraction of time spent with mothers by pups on land changed little between December and May, and the female-pup nutritional bond extended in some cases for up to a year. Nonbreeding adult (?) females increased in numbers near the colony as the summer progressed, then declined near the end. Very young males and some older subadult males were common at the colony site in May, but relatively few very young females were then present. An estimated effective sex ratio of 6.1: 1.0 (females: males) prevailed in the colony during breeding. Sex ratios based on census data consistently underestimated this figure. The annual cycle is characterized by marked synchrony of births: about three-fourths of them fall in a 22-day period. A temporal equivalent of McLaren's "marginal male effect" may selectively favor a short period of pupping and copulation by females, helping to maintain a brief breeding period in the face of ecological determinants of breeding synchrony that are weaker for A. forsteri in New Zealand than for populations of some other pinnipeds. en_US
dc.language.iso en-US en_US
dc.publisher University of Hawai'i Press en_US
dc.title Annual Cycle of Fur Seals, Arctocephalus forsteri (Lesson), on the Open Bay Islands, New Zealand en_US
dc.type Article en_US
dc.type.dcmi Text en_US

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