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Journal Publications
Gunn A. and Irvine R.J. 2003
Subclinical parasitism and ruminant foraging strategies—a review.
Wildlife Society Bulletin 31(1):117–126
(PDF = 148KB)
Abstract
Subclinical parasitism in wild ungulates has been largely neglected,
although it has both explanatory and predictive power in ruminant population
dynamics. This review identifies how subclinical disease from internal
parasites decreases individual reproductive success of their hosts through
reductions in forage intake which reduces body condition. Accumulated
evidence indicates that hosts have evolved adaptive strategies, especially
in foraging behavior, to minimize their exposure to parasites: for example,
reducing the risk of parasitism by avoiding areas of high fecal
contamination. Experimentally, this has been tested
in domestic sheep (Ovis aries), which have been shown to trade the risk of
further infection against forage quality at the scale of bite size and mass.
Appetite reduction, dung aversion, and parasite intensities reducing
fecundity have been demonstrated experimentally in a wild ungulate,
suggesting that using domestic stock as conceptual models is appropriate. We
argue that it is therefore essential to include the interactions between
parasites and host grazing patterns when analyzing broader spatial and
temporal scales of foraging strategies.
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