Predation as a probable mechanism relating winter weather to population dynamics in a North American porcupine population |
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Authors: | Géraldine Mabille Sébastien Descamps Dominique Berteaux |
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Institution: | 1. Chaire de Recherche du Canada en Conservation des écosystèmes Nordiques and Centre d’études Nordiques, Département de Biologie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC, G5L 3A1, Canada
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Abstract: | An abundance index of an eastern Quebec population of North American porcupines (Erethizon dorsatum) has cycled with superimposed periodicities of 11 and 22 years from 1868 to 2000. This cycle closely followed 11- and 22-year
cycles in solar irradiance and local weather (e.g., winter precipitation and spring temperature), generating the hypothesis
that solar activity may affect porcupine abundance through effects on local weather. We investigated the mechanisms linking
porcupine abundance to local weather conditions using a 6-year study (2000–2005) involving individual mark-recapture, radio
tracking, seasonal survival analyses and identification of mortality causes. Summer (May–August) survival was high and constant
over the study period, whereas winter (August–May) survival was lower and varied during the duration of our study. Variations
in local winter precipitation explained 89% of the variation in winter survival. Porcupine predation rates appeared strongly
related to snow conditions; 95% of depredated porcupines were killed when snow was covering the ground, and predation rates
were higher in years with increased winter precipitation. Our data thus support the hypothesis that changes in predation rates
under different snow conditions were the mechanism relating climate to porcupine population dynamics, via modifications of
the local predator–prey interactions and impacts on porcupine winter survival. Our study adds to the growing body of evidence
supporting an effect of climate on predator–prey processes. Also, it identifies one possible mechanism involved in the relationship
between solar irradiance and porcupine population cycles observed at this study site over a 130-year period. |
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Keywords: | Climate Fisher Predator–prey Seasonal survival Solar cycle Species interaction |
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