TY - JOUR
T1 - Mechanisms of population limitation in the southern red-backed vole in conifer forests of western North America
T2 - Insights from a long-term study
AU - Sullivan, Thomas P.
AU - Sullivan, Druscilla S.
AU - Boonstra, Rudy
AU - Krebs, Charles J.
AU - Vyse, Alan
N1 - Funding Information:
We thank Silviculture Branch, British Columbia Ministry of Forests (MoF), Victoria, British Columbia, the Canada-British Columbia Partnership Agreement on Forest Resource Development (FRDA II) for financial support during the first 4 years of the project, and Forest Renewal B.C. through the B.C. Science Council, Gorman Bros. Lumber Ltd., Tolko Industries Inc., Weyerhaeuser Company Limited, Natural Sciences and Engineering Research Council of Canada, and the Applied Mammal Research Institute for financial and logistical support, and H. Sullivan for assistance with fieldwork.
Publisher Copyright:
© 2017 American Society of Mammalogists.
PY - 2017/10/3
Y1 - 2017/10/3
N2 - Our goals were to characterize multiannual population changes of the southern red-backed vole (Myodes gapperi) to determine potential cycling behavior, and to specify the possible causes of these changes. We analyzed a detailed, 21-year record of changes in abundance of M. gapperi in late successional coniferous forest in southern British Columbia, Canada, from 1995 to 2015. We evaluated 3 hypotheses (H), namely that population changes are related to: (H 1) changes in food supply from cone crops of coniferous trees; (H 2) changes in forest habitat associated with beetle-killed lodgepole pine (Pinus contorta) trees; and (H 3) territorial reorganization leading to breeding season declines in abundance. There were 3 cyclic population fluctuations (6- to 7-year periodicity) where red-backed voles reached mean fall numbers of 19-25, 15-16, and 26-27 per ha, respectively; in contrast, only 2-5 voles per ha occurred during population lows. Breeding season declines in abundance occurred in 17 of 21 years, with particularly precipitous drops ranging from 49% to 69% loss of voles. M. gapperi had more successful pregnancies, juvenile recruits, and adult recruits in the high than in the low population years. Mean index of early juvenile survival was 22% higher in low than high population years. Mean summer survival (58%) was consistently lower than that in winter (83%). Population increases were positively related to cone crops of 3 coniferous tree species. Thus, H 1 was partially supported in 3 of 4 seedfall events. Positive changes in forest habitat, resulting from seed rain as a food supply and fallen debris from beetle-killed pine trees as cover, may have supported high numbers of voles in 2011-2012 (H 2). A spring reorganization event limited the number of breeding animals by density-dependent inhibition of maturation and survival of juvenile voles, and led to breeding season declines (H 3). Rigorous field experiments are needed to test these hypotheses and their interactions as mechanisms driving population change.
AB - Our goals were to characterize multiannual population changes of the southern red-backed vole (Myodes gapperi) to determine potential cycling behavior, and to specify the possible causes of these changes. We analyzed a detailed, 21-year record of changes in abundance of M. gapperi in late successional coniferous forest in southern British Columbia, Canada, from 1995 to 2015. We evaluated 3 hypotheses (H), namely that population changes are related to: (H 1) changes in food supply from cone crops of coniferous trees; (H 2) changes in forest habitat associated with beetle-killed lodgepole pine (Pinus contorta) trees; and (H 3) territorial reorganization leading to breeding season declines in abundance. There were 3 cyclic population fluctuations (6- to 7-year periodicity) where red-backed voles reached mean fall numbers of 19-25, 15-16, and 26-27 per ha, respectively; in contrast, only 2-5 voles per ha occurred during population lows. Breeding season declines in abundance occurred in 17 of 21 years, with particularly precipitous drops ranging from 49% to 69% loss of voles. M. gapperi had more successful pregnancies, juvenile recruits, and adult recruits in the high than in the low population years. Mean index of early juvenile survival was 22% higher in low than high population years. Mean summer survival (58%) was consistently lower than that in winter (83%). Population increases were positively related to cone crops of 3 coniferous tree species. Thus, H 1 was partially supported in 3 of 4 seedfall events. Positive changes in forest habitat, resulting from seed rain as a food supply and fallen debris from beetle-killed pine trees as cover, may have supported high numbers of voles in 2011-2012 (H 2). A spring reorganization event limited the number of breeding animals by density-dependent inhibition of maturation and survival of juvenile voles, and led to breeding season declines (H 3). Rigorous field experiments are needed to test these hypotheses and their interactions as mechanisms driving population change.
KW - British Columbia
KW - cone crops
KW - coniferous forest
KW - demographic changes
KW - Myodes gapperi
KW - population fluctuations
KW - red-backed voles
KW - spring reorganization
UR - http://www.scopus.com/inward/record.url?scp=85032875645&partnerID=8YFLogxK
U2 - 10.1093/jmammal/gyx082
DO - 10.1093/jmammal/gyx082
M3 - Article
AN - SCOPUS:85032875645
SN - 0022-2372
VL - 98
SP - 1367
EP - 1378
JO - Journal of Mammalogy
JF - Journal of Mammalogy
IS - 5
ER -