Wildlife Damage Management, Internet Center for
Title
Body Size and Predatory Performance in Wolves: Is Bigger Better?
Document Type
Article
Date of this Version
2009
Abstract
Summary
1.
Large body size hinders locomotor performance in ways that may lead to trade-offs in predator
foraging ability that limit the net predatory benefit of larger size. For example, size-related improvements
in handling prey may come at the expense of pursuing prey and thus negate any enhancement
in overall predatory performance due to increasing size.
2.
This hypothesis was tested with longitudinal data from repeated observations of 94 individually
known wolves (Canis lupus) hunting elk (Cervus elaphus) in Yellowstone National Park, USA. Wolf
size was estimated from an individually based sex-specific growth model derived from body mass
measurements of 304 wolves.
3.
Larger size granted individual wolves a net predatory advantage despite substantial variation in
its effect on the performance of different predatory tasks; larger size improved performance of
a strength-related task (grappling and subduing elk) but failed to improve performance of a
locomotor-related task (selecting an elk from a group) for wolves > 39 kg.
4.
Sexual dimorphism in wolf size also explained why males outperformed females in each of the
three tasks considered (attacking, selecting, and killing).
5.
These findings support the generalization that bigger predators are overall better hunters, but
they also indicate that increasing size ultimately limits elements of predatory behaviour that require
superior locomotor performance. We argue that this could potentially narrow the dietary niche of
larger carnivores as well as limit the evolution of larger size if prey are substantially more difficult
to pursue than to handle.
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Comments
Published in Journal of Animal Ecology 2009, 78, 532–539.