Roads can potentially impact wildlife populations in several negative ways, such as deceasing population vital rates and acting as barriers to dispersal. Here we report preliminary findings on how roads are impacting populations of two common lizard species in the northern Chihuahuan Desert, side-blotched lizards (Uta stansburiana) and western whiptail lizards (Aspidoscelis [Cnemidophorus] marmorata). Our preliminary study site was located on New Mexico State Highway 9, a two-lane road with a low traffic load. Thirty-six pitfall traps with drift-fences were installed in May 2008 and trapped through October. Traps were located on both sides of the road on BLM land, at distances of 0 m, 50 m, and 125 m from the BLM fenceline. All lizards captured were identified to species, measured, marked, and released.
Results/Conclusions
The traps were opened for 54 days during the field season, for a total of 1925 trap-days. Four hundred ninety-three individual lizards (six species) were captured. Side-blotched lizards made up over 72% of captures and had a recapture rate of 28%. Western whiptail lizards made up 21% of captures with a recapture rate of 34%. The road did not have a consistent effect on capture and recapture rates. The number of captures per trap-day is roughly constant with distance from the road for both species. Side-blotched lizards did have higher recapture rates at the sites farthest from the road, suggestive of lower mortality rates. The opposite pattern exists for the western whiptail lizards, with the lowest recapture rates at the sites farthest from the road. These results suggest that these two species of lizards are differentially impacted by this road. However, these were not strong patterns, which is not unexpected on this lightly-traveled road. The study is expanding this year to include sites along Interstate 10, a larger and heavily-traveled road in the same region. We expect to see stronger evidence of road impacts at the new locations.
