Modeling the decline of the Porcupine Caribou Herd, 1989-1998: the importance of survival vs. recruitment

The Porcupine caribou (Rangifer tarandus granti) herd increased from approximately 100 000 animals during the 1970s to 178 000 in 1989, then declined to 129 000 by 1998. Our objective was to model the dynamics of this herd and investigate the potential that lower calf recruitment, as was observed du...

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Main Authors: Stephen M. Arthur, Kenneth R. Whitten, Francis J. Mauer, Dorothy Cooley
Format: Article
Language:English
Published: Septentrio Academic Publishing 2003-04-01
Series:Rangifer
Subjects:
Online Access:https://septentrio.uit.no/index.php/rangifer/article/view/1693
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spelling doaj-eeb103f048e44d93a2dcbadd4a5622a22020-11-24T21:27:59ZengSeptentrio Academic PublishingRangifer1890-67292003-04-0123510.7557/2.23.5.16931578Modeling the decline of the Porcupine Caribou Herd, 1989-1998: the importance of survival vs. recruitmentStephen M. ArthurKenneth R. WhittenFrancis J. MauerDorothy CooleyThe Porcupine caribou (Rangifer tarandus granti) herd increased from approximately 100 000 animals during the 1970s to 178 000 in 1989, then declined to 129 000 by 1998. Our objective was to model the dynamics of this herd and investigate the potential that lower calf recruitment, as was observed during 1991-1993, produced the observed population changes. A deterministic model was prepared using estimates of birth and survival rates that reproduced the pattern of population growth from 1971-1989. Then, parameters were changed to simulate effects of lower calf recruitment and adult survival. Reducing recruitment for 3 years caused an immediate reduction in population size, but the population began to recover in 5-6 years. Even a dramatic temporary reduction in recruitment did not explain the continuing decline after 1995. In contrast, a slight but persistent reduction in adult survival caused a decline that closely followed the observed pattern. This suggests that survival of adults, and perhaps calves, has declined since the late 1980s.https://septentrio.uit.no/index.php/rangifer/article/view/1693Alaskapopulation modelRangifer taranduscariboumodelingpopulation trend
collection DOAJ
language English
format Article
sources DOAJ
author Stephen M. Arthur
Kenneth R. Whitten
Francis J. Mauer
Dorothy Cooley
spellingShingle Stephen M. Arthur
Kenneth R. Whitten
Francis J. Mauer
Dorothy Cooley
Modeling the decline of the Porcupine Caribou Herd, 1989-1998: the importance of survival vs. recruitment
Rangifer
Alaska
population model
Rangifer tarandus
caribou
modeling
population trend
author_facet Stephen M. Arthur
Kenneth R. Whitten
Francis J. Mauer
Dorothy Cooley
author_sort Stephen M. Arthur
title Modeling the decline of the Porcupine Caribou Herd, 1989-1998: the importance of survival vs. recruitment
title_short Modeling the decline of the Porcupine Caribou Herd, 1989-1998: the importance of survival vs. recruitment
title_full Modeling the decline of the Porcupine Caribou Herd, 1989-1998: the importance of survival vs. recruitment
title_fullStr Modeling the decline of the Porcupine Caribou Herd, 1989-1998: the importance of survival vs. recruitment
title_full_unstemmed Modeling the decline of the Porcupine Caribou Herd, 1989-1998: the importance of survival vs. recruitment
title_sort modeling the decline of the porcupine caribou herd, 1989-1998: the importance of survival vs. recruitment
publisher Septentrio Academic Publishing
series Rangifer
issn 1890-6729
publishDate 2003-04-01
description The Porcupine caribou (Rangifer tarandus granti) herd increased from approximately 100 000 animals during the 1970s to 178 000 in 1989, then declined to 129 000 by 1998. Our objective was to model the dynamics of this herd and investigate the potential that lower calf recruitment, as was observed during 1991-1993, produced the observed population changes. A deterministic model was prepared using estimates of birth and survival rates that reproduced the pattern of population growth from 1971-1989. Then, parameters were changed to simulate effects of lower calf recruitment and adult survival. Reducing recruitment for 3 years caused an immediate reduction in population size, but the population began to recover in 5-6 years. Even a dramatic temporary reduction in recruitment did not explain the continuing decline after 1995. In contrast, a slight but persistent reduction in adult survival caused a decline that closely followed the observed pattern. This suggests that survival of adults, and perhaps calves, has declined since the late 1980s.
topic Alaska
population model
Rangifer tarandus
caribou
modeling
population trend
url https://septentrio.uit.no/index.php/rangifer/article/view/1693
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AT francisjmauer modelingthedeclineoftheporcupinecaribouherd19891998theimportanceofsurvivalvsrecruitment
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