|Abstract or Summary
- I assessed potential barriers to dispersal using homing tendency and investigated the movements and settlement site selection of pygmy rabbits (Brachylagus idahoensis) after short distance translocations in southeastern Oregon from June – December 2008. I captured, radio marked, and translocated 59 pygmy rabbits 1-2 km across landscapes with (1) continuous big sagebrush (Artemisia tridentata) cover (n = 19), (2) fragmented patches of big sagebrush cover (n = 19), or (3) continuous big sagebrush cover bisected by a road (n = 21). Radio telemetry was used to monitor the movements and document the fates of translocated individuals. Logistic regression was used to compare the odds of homing among landscapes after accounting for sex and displacement distance of individuals. Geographic information systems (GIS) analysis and spatial analysis software (FRAGSTATS) were used to explore the post-release movements and settlement site selection of pygmy rabbits that failed to home.
Only 15% of translocated pygmy rabbits successfully homed to ˂ 150 m of their original capture locations. Individuals translocated across fragmented landscapes with little cover of big sagebrush were the most likely to home, whereas rabbits translocated across continuous big sagebrush cover bisected by a road were least likely to home. Of the pygmy rabbits that did not home, those translocated across fragmented landscapes moved the farthest (x¯ = 0.95 km, SE = 0.29 km) from their release sites prior to settlement. Individuals that were transported across continuous big sagebrush cover, with and without roads, settled an average of 0.45 (SE = 0.06 km) and 0.35 km (SE = 0.05 km) from their release sites, respectively. There was a general trend of pygmy rabbits settling closer to their release sites as big sagebrush cover increased. Pygmy rabbits also settled on sites that, on average, had greater big sagebrush cover, higher landscape connectivity, and fewer but larger patches of big sagebrush than were present at their capture sites. Current or past presence of conspecifics also appeared to be a factor in selection of settlement sites by pygmy rabbits.
Results of this study indicated that pygmy rabbits were capable of making long distance movements across landscapes with fragmented big sagebrush cover. In addition, pygmy rabbits were observed crossing secondary roads, but they often settled in the dense big sagebrush along road edges where there was increased risk of coyote (Canis latrans) predation. Results of this study suggested that successful translocation of wild pygmy rabbits will require selection of release locations with continuous big sagebrush cover and a history of pygmy rabbit presence. Managers should expect to lose a percentage of pygmy rabbits to homing attempts, post-release dispersal, and predation after translocation, so the release of large numbers of individuals may be required to establish resident populations.