Body mass, territory size and life-history tactics in a socially monogamous canid, the red fox Vulpes vulpes

Iossa, Graziella and Soulsbury, Carl and Baker, Philip and Harris, Stephen (2008) Body mass, territory size and life-history tactics in a socially monogamous canid, the red fox Vulpes vulpes. Journal of Mammalogy, 89 (6). pp. 1481-1490. ISSN 0022-2372

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Official URL: http://dx.doi.org/10.1644/07-MAMM-A-405.1

Abstract

Male-biased sexual size dimorphism is typical of polygynous mammals, where the degree of dimorphism in body
mass is related to male intrasexual competition and the degree of polygyny. However, the importance of body
mass in monogamous mammals is largely unknown. We investigated the effect of body mass on life-history
parameters and territory size in the red fox (Vulpes vulpes), a socially monogamous canid with slight sexual
dimorphism. Increased body size in males appeared to confer an advantage in territory acquisition and defense
contests because heavier males held larger territories and exerted a greater boundary pressure on smaller
neighbors. Heavier male foxes invested more effort in searching for extrapair matings by moving over a wider
area and farther from their territories, leading to greater reproductive success. Males that sired cubs outside their
own social group appeared to be heavier than males that only sired cubs within their social group or that were
cuckolded, but our results should be treated with caution because sample sizes were small. Territory size,
boundary pressure, and paternity success were not related to age of males. In comparison, body mass of females
was not related to territory size, probability of breeding, litter size, or cub mass. Only age affected probability of
breeding in females: younger females reproduced significantly less than did older females, although we did not measure individual nutritional status. Thus, body mass had a significant effect on life-history traits and territory size in a socially monogamous species comparable to that reported in polygynous males, even in the absence of
large size dimorphism.

Item Type:Article
Additional Information:Male-biased sexual size dimorphism is typical of polygynous mammals, where the degree of dimorphism in body mass is related to male intrasexual competition and the degree of polygyny. However, the importance of body mass in monogamous mammals is largely unknown. We investigated the effect of body mass on life-history parameters and territory size in the red fox (Vulpes vulpes), a socially monogamous canid with slight sexual dimorphism. Increased body size in males appeared to confer an advantage in territory acquisition and defense contests because heavier males held larger territories and exerted a greater boundary pressure on smaller neighbors. Heavier male foxes invested more effort in searching for extrapair matings by moving over a wider area and farther from their territories, leading to greater reproductive success. Males that sired cubs outside their own social group appeared to be heavier than males that only sired cubs within their social group or that were cuckolded, but our results should be treated with caution because sample sizes were small. Territory size, boundary pressure, and paternity success were not related to age of males. In comparison, body mass of females was not related to territory size, probability of breeding, litter size, or cub mass. Only age affected probability of breeding in females: younger females reproduced significantly less than did older females, although we did not measure individual nutritional status. Thus, body mass had a significant effect on life-history traits and territory size in a socially monogamous species comparable to that reported in polygynous males, even in the absence of large size dimorphism.
Keywords:red fox, territory size, mating system
Subjects:C Biological Sciences > C120 Behavioural Biology
Divisions:College of Science > School of Life Sciences
ID Code:6442
Deposited By: Carl Soulsbury
Deposited On:05 Oct 2012 14:56
Last Modified:13 Mar 2013 09:16

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