Morphological change in Newfoundland caribou: Effects of abundance and climate

  • Shane P. Mahoney Sustainable Development and Strategic Science, Department of Environment and Conservation, Government of Newfoundland and Labrador, St. John’s, NL A1B 4J6
  • Jackie N. Weir Sustainable Development and Strategic Science, Department of Environment and Conservation, Government of Newfoundland and Labrador, St. John’s, NL A1B 4J6
  • J. Glenn Luther Wildlife Division, Department of Environment and Conservation, Government of Newfoundland and Labrador, Corner Brook, NL, A1A 5J7
  • James A. Schaefer Biology Department, Trent University, Peterborough, ON K9J 7B8
  • Shawn F. Morrison Dryas Research Ltd., Edmonton, AB, T6C 2R6
Keywords: antler, caribou, climate, Newfoundland, competition, diastema, density, morphology, NAO, forage, nutrition, Rangifer tarandus

Abstract

The demographic and environmental influences on large mammal morphology are central questions in ecology. We investigated the effects of population abundance and climate on body size and number of male antler points for the La Poile and Middle Ridge caribou (Rangifer tarandus, L. 1758) herds, Newfoundland, Canada. Across 40 years and 20-fold changes in abundance, adult males and females exhibited diminished stature as indicated by jawbone size (diastema and total mandible length) and the number of antler points at the time of harvest. Associations between jawbone size and population abundance at birth were consistently negative for both herds, both sexes, and all age classes. Large-scale climate patterns, as measured by the North Atlantic Oscillation in the winter prior to birth, were also negatively associated with jawbone size. Declines in male antler size, as measured by the number of antler points, were not well predicted by either abundance or climate, suggesting other factors (e.g., current, rather than latent, foraging conditions) may be involved. We conclude that these morphological changes indicate competition for food resources.
Published
2011-04-01
How to Cite
Mahoney, S. P., Weir, J. N., Luther, J. G., Schaefer, J. A., & Morrison, S. F. (2011). Morphological change in Newfoundland caribou: Effects of abundance and climate. Rangifer, 31(1), 21-34. https://doi.org/10.7557/2.31.1.1917
Section
Articles