Seasonal High Road Mortality of Incilius luetkenii (Anura: Bufonidae) Along the Pan-American Highway Crossing the Guanacaste Conservation Area, Costa Rica

Abstract

The Pan-American Highway in Costa Rica is currently undergoing expansion in capacity as a response to growth in vehicle traffic associated with growing international trade. This highway bisects the Pacific lowlands Tropical Dry Forest of the Guanacaste Conservation Area, a World Heritage site of the United Nations Educational, Scientific and Cultural Organization, with notably high biodiversity, including herpetofauna. As wildlifevehicle collisions are one of the main direct causes of animal mortality, we quantified the species composition, seasonality, and location of amphibians and reptiles killed along a 30 km segment of the highway running through the conservation area. From August 2016 to February 2017, we mapped roadkill hotspots using Kernel Density Estimation (KDE) with KDE+ software. We detected 1,298 carcasses of 28 species, including seven anuran, one caecilian, three lizard, 15 snake, and two turtle species; the Neotropical Yellow Toad (Incilius luetkenii) comprised over half the total roadkill. The two most severe roadkill hotspots were short road segments near seasonally flooded depressional wetlands where I. luetkenii and other anurans breed. We urge construction of mitigation measures including barriers and subterranean passages to conserve amphibian populations, especially if the Pan-American Highway will be widened at these sites.