Maternal investment in Steller sea lions in Alaska /
Differences among rookeries and between pup sexes in maternal investment in Steller sea lions in Alaska were investigated during the first six weeks postpartum. Several indices of maternal investment were measured, including adult female attendance pattern, diurnal timing of foraging trips, female...
| Main Author: | |
|---|---|
| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
2000.
|
| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=728408421&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Differences among rookeries and between pup sexes in maternal investment in Steller sea lions in Alaska were investigated during the first six weeks postpartum. Several indices of maternal investment were measured, including adult female attendance pattern, diurnal timing of foraging trips, female field metabolic rates, pup size and body composition at birth, and pup growth during early lactation. The null hypothesis was that there were no differences among rookeries or between pup sexes in maternal investment. The alternative hypothesis was that there were differences among rookeries and pup sexes in maternal investment. By investigating potential differences among rookeries I examined the validity of one of the leading hypotheses explaining the cause of the population decline of Steller sea lions in the Gulf of Alaska and the Aleutian Islands relative to the stable population in Southeast Alaska. Male pups (22.6 kg ±0.26 SE, n=71) were significantly heavier than female pups (19.6 kg ±0.21 SE, n=74) at 0-5 days of age. Male and female pups grew at the same rate, in terms of mass, standard length, and axillary girth during the first six weeks postpartum. There were no significant differences by rookery in pup mass at 0-5 days of age. When compared by rookery, body mass and standard length increased at a faster rate for pups in the declining population (0.28-0.48 kg/d and 0.22-0.53 cm/d) than in the stable population (0.23 kg/d and 0.20 cm/d). Adult females showed a cline in length of time spent at sea in their attendance pattern during early lactation (7.1-25.6 h), with females in the stable population making the longest trips. While females in both areas spent the same average number of hours onshore between trips (20.7-25.2 h), because of their short trips females in the declining population spent a higher percentage of their time onshore (53-76%). The results of this study indicate that there is differential maternal investment in male and female pups during gestation, but not during early lactation. There are differences among rookeries, but there is no evidence that sea lions in the declining population are nutritionally stressed. |
|---|---|
| Item Description: | Vita. "Major Subject: Wildlife and Fisheries Sciences". |
| Physical Description: | xii, 137 leaves : illustrations, maps ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 99-121). |