CHARACTERISTICS OF A WHITE-FOOTED MOUSE (PEROMYSCUS-LEUCOPUS) POPULATION INHABITING A POLYCHLORINATED-BIPHENYLS CONTAMINATED SITE

Demographic characteristics of a white-footed mouse (Peromyscus leucop us) population inhabiting a woodland containing a low level of PCBs co ntamination were compared to an uncontaminated reference site. Althoug h population density was higher on the PCBs-contaminated grid, the pop ulation exhibited greater temporal variability among years and had a h igher number of transient animals. These population trends are consist ent with those observed in structurally suboptimal habitats, indicatin g that the PCBs-contaminated grid is functioning as a suboptimal habit at. However, the data are not compelling enough to firmly conclude tha t the differences are due to contamination rather than to undetected e nvironmental variation between sites. If demographic differences due t o contamination are slight, they will be difficult to detect against a background of demographic variation resulting from subtle environment al differences. We conclude that animals at this site experienced a le vel of contamination that was below threshold for unequivocal detectio n of demographic effects.