Obtaining estimates of absolute abundance for rare or cryptic species can be challenging. In these cases, methods using indirect indicators such as sign might offer useful indices of population size. Pygmy rabbits (Brachylagus idahoensis) are small, burrowing lagomorphs for which methods for population assessment and monitoring are needed. Current tools for estimating relative abundance rely on detecting and assessing fecal pellets and burrow systems. We evaluated temporal changes in each of these indicators to gauge their potential usefulness as indicators of relative and absolute abundance of pygmy rabbits. Pellet persistence was strongly influenced by environmental exposure, and based on our data, we estimated that maximum persistence of fecal pellets would be 24–34 months. Pellet appearance (color) was affected by both time and exposure. Burrow systems were remarkably resilient over the course of the study. Probability of burrow systems transitioning between activity classes (active, recent, and old) did not vary detectably by study site, season, or year. We suggest that 2 protocols currently used for classification of pygmy rabbit burrow systems are most useful for different applications. Further work is needed, however, to link such assessments to quantitative estimates of population size.
Sanchez, Dana M.; Rachlow, Janet L.; Robinson, Andrew P.; and Johnson, Timothy R.
"Survey indicators for pygmy rabbits: temporal trends of burrow systems and pellets,"
Western North American Naturalist: Vol. 69
, Article 2.
Available at: http://scholarsarchive.byu.edu/wnan/vol69/iss4/2