Trapping efficiency for foxes (Vulpes vulpes) in central New South Wales: age and sex biases and the effects of reduced fox abundance

A total of 276 red foxes (Vulpes vulpes) was captured over 40 597 trap-nigh ts during 1994-96 at three separate sites in central New South Wales, resul ting in an overall trapping efficiency of one fox per 147 trap-nights. Trap ping using multiple trap sets placed at carcases was 3.2 times more efficie nt than trapping using single trap sets. During 1994-95, when two of the si tes suffered a severe drought, fox abundance declined to less than 0.2 foxe s km(-1) of spotlight transect; trapping efficiency at those sites also dec lined, to an average of one fox per 315 trap-nights. Mean trapping efficien cy for non-drought periods was one fox per 135 trap-nights, 2.3 times more efficient than during the drought period. In 1995 and 1996, 353 foxes were shot in areas adjacent to each site. This gave the opportunity to compare s ex and age biases between the trapped and shot samples: the ratio of males to females was significantly higher in the trapped sample than in the shot sample, and there was also a significantly higher ratio of adults to juveni les in the trapped sample than in the shot sample.