Authors

J. D. Roth; J. D. Marshall; D. L. Murray; D. M. Nickerson;T. D. Steury

Comments

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Abbreviated Journal Title

Ecology

Keywords

alternative prey; Canada lynx; lepus americanus; lynx canadensis; population cycles; snowshoe hare; specialist/generalist predation; hypothesis; stable isotope ratios.; TEMPORAL VARIABILITY; STABLE ISOTOPES; CARBON ISOTOPES; SNOWSHOE HARES; 10-YEAR CYCLE; RED SQUIRRELS; PREDATION; PATTERNS; NITROGEN; EXPLANATION; Ecology

Abstract

Geographical gradients in the stability of cyclic populations of herbivores and their predators may relate to the degree of specialization of predators. However, such changes are usually associated with transition from specialist to generalist predator species, rather than from geographical variation in dietary breadth of specialist predators. Canada lynx (Lynx canadensis) and snowshoe hare (Lepus americanus) populations undergo cyclic. fluctuations in northern parts of their range, but cycles are either greatly attenuated or lost altogether in the southern boreal forest where prey diversity is higher. We tested the influence of prey specialization on population cycles by measuring the stable carbon and nitrogen isotope ratios in lynx and their prey, estimating the contribution of hares to lynx diet across their range, and correlating this degree of specialization to the strength of their population cycles. Hares dominated the lynx diet across their range, but specialization on hares decreased in southern and western populations. The degree of specialization correlated with cyclic signal strength indicated by spectral analysis of lynx harvest data, but overall variability of lynx harvest (the standard deviation of natural-log-transformed harvest numbers) did not change significantly with dietary specialization. Thus, as alternative prey became more important in the lynx diet, the fluctuations became decoupled from a regular cycle but did not become less variable. Our results support the hypothesis that alternative prey decrease population cycle regularity but emphasize that such changes may be driven by dietary shifts among dominant specialist predators rather than exclusively through changes in the predator community.

Journal Title

Ecology

Volume

88

Issue/Number

11

Publication Date

1-1-2007

Document Type

Article

Language

English

First Page

2736

Last Page

2743

WOS Identifier

WOS:000251067900009

ISSN

0012-9658

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