absolute density

Stoat (Mustela erminea) density was estimated by live-trapping in a South Island Nothofagus forest, New Zealand, at 8-9 (Jan/Feb 1996) and 15-16 (Aug/Sep 1996) month intervals after significant beech seedfall in autumn 1995. Absolute densities were 4.2 stoats per km² (2.9-7.7 stoats per km², 95% confidence intervals) in Jan;Feb 1996 and 2.5 stoats per km² (2.1-3.5 stoats per km²) in Aug/Sep 1996. Trappability of stoats increased in the latter sampling period, probably because mice (Mus musculus) had become extremely scarce.

Estimating the detection probability of introduced organisms during the pre-monitoring phase of an eradication effort can be extremely helpful in informing eradication and post-eradication monitoring efforts, but this step is rarely taken. We used data collected during 11 nights of mark-recapture sampling on Aguiguan, Mariana Islands, to estimate introduced kiore (Rattus exulans Peale) density and detection probability, and evaluated factors affecting detectability to help inform possible eradication efforts.