Factors Affecting the Timing of Movements to Hibernation Sites by Western Toads (Anaxyrus boreas)

Abstract

Toads in northern climates may spend seven months or more in hibernation; therefore, behavioral decisions related to hibernation are important for survival. We examined factors influencing the timing and nature of movements to hibernation sites by western toads (Anaxyrus boreas, formerly Bufo boreas) at three study areas in north-central Alberta, Canada, with the use of radiotracking. We found that small toads arrived at the general vicinity of their hibernation sites earlier than larger toads. Entry date into hibernation sites was similar for toads of all sizes. Arrival and entry dates were both significantly related to temperature and/or day length. Larger toads moved to hibernation sites later in the year and moved along straighter paths to reach these sites. We propose that larger toads are older individuals that are familiar with their landscape and locations of suitable hibernacula and that they maximize their fitness by remaining at good foraging grounds as late in the year as possible.