Deer Mouse Repopulation of a Poisoned Douglas-Fir Clearcut

Repopulation by deer mice (Peromyscus maniculatus rubidus) after baiting a clearcut area with compound 1080 (sodium fluoroacetate) was studied on the Mt. Hood National Forest, Oregon, at an elevation of about 2,000 feet in the Douglas-fir (Pseudotsuga menziesii) timber type. The poisoned clearcut and a similar untreated check clearcut nearby were live-trapped from November 1952 to December 1953. The December 1, 1952 poisoning appeared to be about 100 percent effective on the resident deer mouse population. However, although the bait was effective at least 38 days, animals were infiltrating the area 15 to 19 days after baiting. Within 5 to 7 months the population had reached about the same relationship with the check area as it had before baiting. Dispersal was responsible for most of the December and January repopulation; subadults appeared to be the most active colonizers. The first immature mouse was trapped on the poisoned area in February. Post-mortem examination revealed breeding deer mice in the vicinity every month except December 1953. The data suggested that more breeding occurred on the poisoned than on the check area.