Feeding Specialisations

Journal

Canadian Journal of Zoology, January 2002, Vol. 80, No. 1, pp. 83-93(11)

Authors

Revilla E. and Palomares F.

Abstract

Several local populations of the otherwise trophic-generalist Eurasian badger have been defined as specialising locally on variable food resources such as earthworms, olive fruits, or young rabbits, owing to a lack of correlation between resource availability and use. However, theoretical models predict that temporal variation in resources reduces the probability of diet specialisation.

To understand the relationship between temporal resource variability and local feeding specialisation, we studied temporal variation in diet composition and diversity (using faecal analysis), the availability of a temporally stable key resource, and the relation between consumption and availability of rabbits (key prey) and invertebrates (secondary prey) for a badger population previously described as specialised on young rabbits. 

We found strong variations in the use of different resources (including young rabbits) and in diet diversity among seasons and years. The main food resource was young rabbits during winter and spring, fruits in autumn, and reptiles in summer. Diet diversity was inversely related to consumption of young rabbits and directly related to consumption of secondary prey (invertebrates). Consumption of rabbits (both young and adults) was correlated with their abundance in the field, with a type 3 functional response in the consumption of young rabbits, which is typical of a generalist to whom alternative prey are available. There was no relationship between the abundance of invertebrates and their consumption. Our results show that badgers in the study area were not locally specialised, therefore care should be taken when referring to a population as specialised without an adequate test of the predictions.

Web site

http://www.ingenta.com