Analyzing The Impact Of Traffic Fatalities On Lava Lizard Populations (Microlophus Albemarlensis) In Santa Cruz, Galápagos, With Relation To Land Use And Potential For Fragmentation In The Landscape
Dawn R. Tanner, Dept. of Conservation Biology, University of Minnesota, St. Paul, MN 55108; (651) 290-2404; tann0042@umn.edu
James A. Perry, Dept. of Conservation Biology, University of Minnesota, St. Paul, MN 55108
Vehicle collisions with wildlife negatively impact species everywhere roads divide and transect natural habitats. This can be especially intense in areas where roads are a new addition to the landscape. This study addresses the impact of traffic fatalities on lava lizards, Microlophus albemarlensis, on the island of Santa Cruz, Galápagos. The main road bisecting the island north to south was a new addition to the island, begun in 1974 but not completed with asphalt until 2000. We assessed impacts occurring due to an increase in the amount of traffic and speed of travel on the island. Previous road-impact studies outside Galápagos have dealt with amphibian and reptile species, but few focus on lizard populations. On the island of Santa Cruz, ongoing studies are employed to monitor impacts on endemic bird populations. This study expands existing knowledge by focusing on lizards and addressing these impacts. Using Poisson Regression to analyze transect data at incremental positions from the road, we found a 30% increase in lizard abundance per 100 meters distant from the road, with significant results also between natural vegetation zones with little human impact and highly impacted areas with invasive species. By traveling the length of the 40-kilometer road, we were able to identify hot spots for fatalities of both lizards and birds, which will be used to recommend remediation strategies and target areas for future concentration of protection efforts. Finally, we used incidence of tail loss for lizards killed on the road and those located in transects to quantify additional energetic costs for lizards inhabiting territories near the road. The results of this were striking: 29% on the road, 10% adjacent to the road, with numbers quickly reduced, arriving at 1% at 400 meters distant. These results will be used to direct and focus future management efforts.