Characterizing Movement Patterns and Spatio-temporal Use of Under-road Tunnels by Long-toed Salamanders in Waterton Lakes National Park, Canada

Abstract

Linnet Lake (Waterton Lakes National Park, Alberta) is the breeding site of a population of Long-toed Salamanders (Ambystoma macrodactylum) that has decreased dramatically over the last 15 years, partially due to vehicle-caused mortality occurring on an adjacent road. In May 2008, Parks Canada installed four amphibian tunnels under this road. We installed drift fences to direct salamanders toward tunnel entrances and monitored tunnel use with pitfall traps in 2008 and 2009. We used logistic regressions and Akaike's Information Criterion (AIC) to determine if probability of tunnel use differed among individual salamanders. Salamander road mortality decreased from 10% of the population to <2% following installation of tunnels and fences. In 2009, 104 salamanders were documented using tunnels. Salamanders were 20 times more likely to use tunnels when traveling to the breeding site than when leaving the site. Distance from tunnel entrances, sex, and body size did not have significant effects on tunnel use by salamanders. Although salamander movement was positively correlated with occurrence of precipitation, this relationship was much stronger when salamanders were leaving the breeding site. Variation in use between the four tunnels was positively correlated with soil moisture of surrounding habitat. Continued monitoring will be needed to determine if tunnel use by Long-toed Salamanders increases through time, and if decreased road mortality translates into population gains.