Influences of supplemental feeding on winter elk calf:cow ratios in the southern Greater Yellowstone Ecosystem

Journal of Wildlife Management
By: , and 

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Abstract

Several elk herds in the Greater Yellowstone Ecosystem are fed during winter to alleviate interactions with livestock, reduce damage to stored crops, and to manage for high elk numbers. The effects of supplemental feeding on ungulate population dynamics has rarely been examined, despite the fact that supplemental feeding is partially justified as necessary for maintaining or enhancing population growth rates. We used linear regression to assess how the presence of feedgrounds, snowpack, summer rainfall, indices of grizzly bear density and wolves per elk, elk population trend counts, brucellosis seroprevalence, and survey date were correlated with midwinter calf:cow ratios, a metric correlated with population growth, from 1983–2010 from 12 ecologically similar elk herd units (7 fed and 5 unfed) in Wyoming, USA. Our statistical approach allowed for rigorous tests of the hypotheses that supplemental feeding had positive effects on calf:cow ratios and reduced sensitivity of calf:cow ratios to bottom-up limitation relative to top-down limitation from native predators. Calf:cow ratios generally declined across all herd units over the study period and varied widely among units with feedgrounds. We found no evidence that the presence of feedgrounds had positive effects on midwinter calf:cow ratios in Wyoming. Further, fed elk showed stronger correlations with environmental factors, whereas calf:cow ratios for unfed elk showed stronger correlations with predator indices. Although we found no consistent association between winter feeding and higher calf:cow ratios, we did not assess late winter mortality and differences in human offtake between fed and unfed regions, which remain a priority for future research. 

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Influences of supplemental feeding on winter elk calf:cow ratios in the southern Greater Yellowstone Ecosystem
Series title Journal of Wildlife Management
DOI 10.1002/jwmg.908
Volume 79
Issue 6
Year Published 2015
Language English
Publisher Wildlife Society
Contributing office(s) Northern Rocky Mountain Science Center, Contaminant Biology Program
Description 11 p.
First page 887
Last page 897
Country United States
State Wyoming
Other Geospatial Greater Yellowstone Ecosystem
Online Only (Y/N) N
Additional Online Files (Y/N) N