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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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 |
work_keys_str_mv |
AT stephenmarthur modelingthedeclineoftheporcupinecaribouherd19891998theimportanceofsurvivalvsrecruitment AT kennethrwhitten modelingthedeclineoftheporcupinecaribouherd19891998theimportanceofsurvivalvsrecruitment AT francisjmauer modelingthedeclineoftheporcupinecaribouherd19891998theimportanceofsurvivalvsrecruitment AT dorothycooley modelingthedeclineoftheporcupinecaribouherd19891998theimportanceofsurvivalvsrecruitment |
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