Movement and habitat-use of the Great Basin Spadefoot (Spea Intermontana) at its northern range limit

The Great Basin Spadefoot (Spea intermontana) ranges from Arizona to British Columbia (BC) in western North America, being typically associated with arid environments. However, at the northern limit of the species (south-central BC), the ecosystem contains only small patches of grassland interspersed within a forested landscape, and the climate is cool and wet compared to the core of the spadefoot range. Due to the threatened status of spadefoots in BC, breeding ponds have been identified, but effective management requires data on habitat use away from these bodies of water. Using telemetry, I examined movement patterns and determined habitat associations of diurnal retreat sites (shallow self-made or pre-existing burrows) for these animals. I was able to track 19 spadefoots for varying lengths of time over two active seasons in 2009 and 2010. In general, telemetered spadefoots showed periodic, eruptive movements, where single (used one time only) or core (used multiple times) retreat sites were utilized for a period of time, prior to larger movements that took the animal to another area (with another set of retreat sites). Often retreat sites were used repeatedly; individuals would emerge to forage, travel to breeding ponds, and/or utilize other sites, sometimes retracing their movement patterns over large distances. The majority of terrestrial habitat used was within 112 m from breeding ponds and 136 m was the average maximum displacement, although telemetered spadefoots ventured up to 370 m from aquatic habitat. Grassland and forest path habitat-types types were selected by spadefoots at a higher proportion than in random locations. At a smaller scale within these macro-habitats, spadefoots selected for retreat sites containing higher proportions of bare ground and rock compared to random locations. This study provides much-needed background information on the behaviour and terrestrial habitat preferences of Great Basin spadefoots, and can be used to inform management strategies for this species at the northern extent of their geographic range.