Fragmentation of sagebrush communities: does an increase in habitat edge impact pygmy rabbits?

Abstract

AbstractSagebrush (Artemisia spp.) communities are ecologically critical; however, these areas currently face severe threats from alteration and reduction. Pygmy rabbits Brachylagus idahoensis are sagebrush specialists that occupy the intermountain region of the USA. Little is known concerning how fragmentation of sagebrush and an increase in habitat edge may impact pygmy rabbits. From 2004 to 2009 in Utah, USA, we tested hypotheses concerning the influences of habitat edge on pygmy rabbits. We quantified the number of active pygmy rabbit burrows in relation to distance from habitat edge. At differing distances from habitat edge, we also deployed remote cameras at burrows and counted fecal pellets to document potential increases in the number of terrestrial predators and competitors. We classified activity of 528 burrows (284 active and 244 inactive). The proportion of active burrows was lower within 100 m of habitat edge (r2=0.502, P=0.02) compared with burrows located in control areas (>100 m from habitat edge). Photographs of pygmy rabbits decreased at burrows closer to habitat edge (P<0.01). Photographs of predators increased near habitat edge, but was marginally insignificant (P=0.07), and photographs of potential competitors [cottontail (Sylvilagus spp.), P<0.01; jackrabbit Lepus californicus, P<0.01] increased near habitat edge. Fecal pellet plots supported these patterns. Our results indicated that the proportion of active burrows and the relative abundance of pygmy rabbits were reduced near habitat edge. This reduction was associated with an increase in terrestrial predators and competitors near habitat edge. Consideration should be given to the influence of habitat edge on pygmy rabbits in order to conserve and manage this unique species.