Northern fur seal reproductive rates and early maternal care
The majority of the world's breeding population of northern fur seals (Callorhinus ursinus) is found on the Pribilof Islands (St. Paul and St. George) in the Bering Sea, Alaska. Pup production on these islands experienced an irregular but overall decline since the early 1970's. Between 199...
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ftoregonstate:ir.library.oregonstate.edu:5m60qv40s 2024-09-09T19:33:53+00:00 Northern fur seal reproductive rates and early maternal care Kunisch, E. (Erin) Horning, Markus Gelatt, Tom Estill, Charles Dugger, Katie Fisheries and Wildlife Oregon State University. Graduate School https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/5m60qv40s English [eng] eng unknown Oregon State University https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/5m60qv40s All rights reserved Northern fur seal -- Alaska -- Pribilof Islands -- Reproduction Northern fur seal -- Fertility -- Alaska -- Pribilof Islands Masters Thesis ftoregonstate 2024-07-22T18:06:05Z The majority of the world's breeding population of northern fur seals (Callorhinus ursinus) is found on the Pribilof Islands (St. Paul and St. George) in the Bering Sea, Alaska. Pup production on these islands experienced an irregular but overall decline since the early 1970's. Between 1998 and 2010, pup production declined precipitously at an annual rate of 4.9% on the Pribilof Islands, and 5.5% on St. Paul Island. Specific reasons for this decline remain unknown, and contemporary estimates for many vital rate parameters including reproductive rates are unavailable. This study determined a contemporary estimate of natality and fertility rates, as well as reproductive timing on the Polovina Cliffs rookery of St. Paul Island during the 2008 (30 June-31 August) and 2009 (1 July-25 August) breeding seasons. Natality rate (defined as the number of pups born divided by the number of reproductively mature females) was determined from visual observations of parturition or associated maternal behavior in 208 and 217 individually marked females (via flipper tags) in 2008 and 2009, respectively. Data yielded observed natality estimates of 0.79 in 2008 and 0.88 in 2009. The fertility rate (defined as the number of pups born divided by the total number of females present, irrespective of reproductive maturity/age) was determined for the 2008 breeding season only. This ratio of total pup to female counts was derived from adjusted daily cross-sectional counts conducted through the breeding season. Maximum pup and female counts were derived as asymptotes of sigmoid growth models fitted to corrected daily counts. Live pup counts were corrected for mortalities by estimates of cumulative pup mortalities. Daily counts of females present in the rookery were corrected for reduced detection probabilities resulting from increased maternal foraging trip durations through the season, typical of attendance patterns associated with colonial, income breeders. Daily detection probabilities for individually marked females were generated from ... Master Thesis Bering Sea Alaska Callorhinus ursinus Northern fur seal ScholarsArchive@OSU (Oregon State University) Bering Sea |
institution |
Open Polar |
collection |
ScholarsArchive@OSU (Oregon State University) |
op_collection_id |
ftoregonstate |
language |
English unknown |
topic |
Northern fur seal -- Alaska -- Pribilof Islands -- Reproduction Northern fur seal -- Fertility -- Alaska -- Pribilof Islands |
spellingShingle |
Northern fur seal -- Alaska -- Pribilof Islands -- Reproduction Northern fur seal -- Fertility -- Alaska -- Pribilof Islands Kunisch, E. (Erin) Northern fur seal reproductive rates and early maternal care |
topic_facet |
Northern fur seal -- Alaska -- Pribilof Islands -- Reproduction Northern fur seal -- Fertility -- Alaska -- Pribilof Islands |
description |
The majority of the world's breeding population of northern fur seals (Callorhinus ursinus) is found on the Pribilof Islands (St. Paul and St. George) in the Bering Sea, Alaska. Pup production on these islands experienced an irregular but overall decline since the early 1970's. Between 1998 and 2010, pup production declined precipitously at an annual rate of 4.9% on the Pribilof Islands, and 5.5% on St. Paul Island. Specific reasons for this decline remain unknown, and contemporary estimates for many vital rate parameters including reproductive rates are unavailable. This study determined a contemporary estimate of natality and fertility rates, as well as reproductive timing on the Polovina Cliffs rookery of St. Paul Island during the 2008 (30 June-31 August) and 2009 (1 July-25 August) breeding seasons. Natality rate (defined as the number of pups born divided by the number of reproductively mature females) was determined from visual observations of parturition or associated maternal behavior in 208 and 217 individually marked females (via flipper tags) in 2008 and 2009, respectively. Data yielded observed natality estimates of 0.79 in 2008 and 0.88 in 2009. The fertility rate (defined as the number of pups born divided by the total number of females present, irrespective of reproductive maturity/age) was determined for the 2008 breeding season only. This ratio of total pup to female counts was derived from adjusted daily cross-sectional counts conducted through the breeding season. Maximum pup and female counts were derived as asymptotes of sigmoid growth models fitted to corrected daily counts. Live pup counts were corrected for mortalities by estimates of cumulative pup mortalities. Daily counts of females present in the rookery were corrected for reduced detection probabilities resulting from increased maternal foraging trip durations through the season, typical of attendance patterns associated with colonial, income breeders. Daily detection probabilities for individually marked females were generated from ... |
author2 |
Horning, Markus Gelatt, Tom Estill, Charles Dugger, Katie Fisheries and Wildlife Oregon State University. Graduate School |
format |
Master Thesis |
author |
Kunisch, E. (Erin) |
author_facet |
Kunisch, E. (Erin) |
author_sort |
Kunisch, E. (Erin) |
title |
Northern fur seal reproductive rates and early maternal care |
title_short |
Northern fur seal reproductive rates and early maternal care |
title_full |
Northern fur seal reproductive rates and early maternal care |
title_fullStr |
Northern fur seal reproductive rates and early maternal care |
title_full_unstemmed |
Northern fur seal reproductive rates and early maternal care |
title_sort |
northern fur seal reproductive rates and early maternal care |
publisher |
Oregon State University |
url |
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/5m60qv40s |
geographic |
Bering Sea |
geographic_facet |
Bering Sea |
genre |
Bering Sea Alaska Callorhinus ursinus Northern fur seal |
genre_facet |
Bering Sea Alaska Callorhinus ursinus Northern fur seal |
op_relation |
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/5m60qv40s |
op_rights |
All rights reserved |
_version_ |
1809903414136537088 |