Evaluation of injuries to Virginia opossums captured in the EGG (TM) trap

Concern about animal welfare has stimulated much research and development o f restraining traps considered more humane to capture furbearers. However, in formation about injuries to Virginia opossums (Didelphis virginiana) cap tured in such devices remains limited. We evaluated injuries sustained by o possums captured in the EGG(TM) trap. We caught all animals in central Illi nois during the 1996 and 1997 trapping seasons. Traps were staked solidly a nd checked daily beginning in early morning. We determined trap-related inj uries using radiographs and whole body necropsies. The mean total (whole bo dy) injury score based on a modified Olsen scoring system was 47 (n=40, ran ge=1-223, SE=11). Most opossums (75%) had total injury scores <50. We calcu lated an injury performance threshold of 123 points for the EGG (i.e., base d on our study, greater than or equal to 70% of the opossums captured in EG G traps could be expected to score less than or equal to 123 points with 95 % confidence). Severe injury scores (those >125) were limited to opossums w eighing less than or equal to 1.9 kg. Injury scores for small (less than or equal to 1.9-kg) opossums (n=10) were higher than those for large (>1.9-kg ) opossums (n=30) (P=0.002). We recommend additional field testing to compa re efficiency of the EGG trap with other restraining devices commonly used to capture opossums.