Investigation of the Asian Chipmunk (Eutamias sibiricus Laxmann 1769) in De Panne (Belgium)
The Asian chipmunk is being imported in Belgium as a pet since the beginning of the sixties. Now there are four free-living populations in Belgium, one in the ZoniÃ«nwoud (Brussels, estimated at 18.000 individuals in 2000!), one in Westerlo, one in a Castle park in Zwijnaarde and the one from this study in the Calmeynbos in De Panne. About 20 years ago, 17 animals were released in the Calmeynbos by the amusement park Meli. In their original distribution area these animals can, at high densities, cause a lot of damage to agricultural fields. In the ZoniÃ«nwoud a negative influence on some ground breeding birds is indicated. Because of the danger of negative consequences on the ecological system due to increasing population pressure, preventive measures have been suggested. There is the need of a more specific study of the interaction of the chipmunks with the forestal ecological system. At first step taken in this direction is this study, conducted in fall 1998, 1999 and 2000 in De Panne.
The aim of this project is to estimate chipmunk numbers and distribution and to look at their behaviour (especially feeding habits). The study includes two parts : (1) an estimation of the population density based on the transect method in the whole study area and (2) a more accurate estimation of the population density based on capture-mark-recapture data in part of the study area.
The chipmunks preferred the forested area but in years with high densities they spread out in the surrounding gardens and dunes. Estimates were about 350 chipmunks in 1998, 160 in 1999 and 70 in 2000, so there seems to be a decrease in population size. The low number of chipmunks left in 2000 were concentrated in the part of the forest with the most food. The forest is divided by a road, with remarkable differences in sex ratio between both sides: at one side, with a low chipmunk density, sex ratio was about 1:1, while at the other side, with much higher densities, there were about 4 females for 1 male.