Sexual dimorphism in cranial size and shape among red foxes Vulpes vulpes
from north-east Ireland
Lynch JM
BIOLOGY AND ENVIRONMENT-PROCEEDINGS OF THE ROYAL IRISH ACADEMY 96B
(1): 21-26 JUN 1996
Abstract:
Sexual dimorphism in cranial form was investigated for a sample of 204 adult red
foxes Vulpes vulpes from north-east Ireland. Using a combination of principal
component analysis and discriminant function analysis, size variation and allometry
was found to account for 65.29% of the between-sex variation. The crania of male
foxes were larger, more elongate and had a relatively narrower post-orbital constriction
than those of the female of the species. A set of discriminant functions allowed
sexing of unsexed material with over 86% accuracy. Discriminant functions derived
from English and Welsh fox populations were found to sex Irish foxes with 78.4%
and 85.8% accuracy, thus indicating that discriminant functions may not be entirely
population-specific. These findings were discussed in the light of other studies
of dimorphism in the species and on the 'adaptive' nature of such shape variation
in carnivores.