J.J.A. Dekker : "Rabbits, refuges and resources. How foraging of herbivores is affected by living in burrows"

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9 May 2007 13:30
Unit: Wageningen University
Location: Aula, building 362, Gen. Foulkesweg 1, Wageningen
Organisation: Wageningen University
Promotor: prof.dr. H.H.T. Prins (Resource ecology)
Co Promotor: Dr. S.E. van Wieren

 Small herbivores such as rabbits, pika and marmots create spatial patterns in vegetation around their burrows by grazing. On the 9th of May 2007, Ir. Jasja Dekker (Resource Ecology Group, Wageningen University), defends his PhD thesis, which focuses on these refuge-living herbivores.

By performing experiments with rabbits, he showed that looking for predators causes the spatial patterns: this costs more foraging time as the burrow is farther, causing a preference for foraging close to the burrow. The animals can stay close to their burrow when the vegetation grows, but are forced to graze larger areas as plant growth declines, and are negatively affected by the seasonal deterioration of plant quality. Models predict that this will have repercussions for population density, but can be countered by large grazers. Ir. Dekker also showed that large grazers also affect refuge living herbivores through changes in vegetation structure: this alters the timing of their activity.

The spatial variation in grazing by refuge living herbivores potentially increases variation in structure and diversity in the vegetation. That way, these small, refuge living herbivores are an important addition to large grazers.
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