Belgian Red Squirrel PhD Project

Goedele Verbeylen

Dispersal and population dynamics of red squirrels (Sciurus vulgaris L. 1758) in highly fragmented woodlands

(Supervisor : Prof. Dr. Erik Matthysen, co-supervisor : Dr. Luc Wauters)

Red squirrels are typical inhabitants of North and Central Europe’s large forests. In large parts of Western Europe though, their habitat is strongly fragmented. A central hypothesis in the study of habitat fragmentation is that increasing isolation of habitat fragments decreases dispersal between them. In small populations this can lead to local extinction, compensated or not by later recolonization, and a higher degree of inbreeding. Until now this hypothesis is supported mainly by indirect studies (correlative research). To gain more insight in the functioning of squirrel populations in forest fragments, an intensive study on dispersal and population dynamics started in 1994 in a fragmented landscape where woodlands occur as small patches. The Eurasian red squirrel (Sciurus vulgaris L. 1758) is used as study species, because it’s density is not too high to mark all animals in the population and because fragmentation is known to affect the dynamics of small populations. The study area is an archipelago of woodland fragments situated in the province of Antwerp (Belgium), that contains 58 woodlands (between 0.08 and 57 ha, with only 15 > 3.5 ha) covering 6.5 % of the total area. These woodland fragments have different size, shape and tree species composition and are connected (in different degrees) by tree- and hedgerows. Squirrels were (re)captured bimonthly in all fragments. They got a transponder (for individual recognition, were weighed, sexed, aged, sexual status was noted, hind feet were measured and a skin sample was taken. This provides data on condition, reproduction, fluctuating asymmetry and population structure. To get information on home ranges and dispersal, each squirrel was radio-tracked once or twice a fortnight (and every 1 or 2 days for juveniles and dispersing adults). This was done by foot, car or, if necessary, by helicopter, depending on how far the squirrels dispersed. Microsatellite DNA fingerprinting will be used to study parenthood (to determine the origin of new squirrels that come into the population) and genetic diversity of local populations. Food abundance was estimated.

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