A Road Survey of Amphibians and Reptiles in a Bottomland Hardwood Forest

Abstract

The impact of roads on amphibian and reptile numbers at Texas Parks and Wildlife Department's Old Sabine Bottom Wildlife Management Area (OSBWMA), a bottomland hardwood forest was studied from 1 June 2003 to 1 June 2004 by vehic- ular and pedestrian surveys. One weekly survey was conducted in the morning and the other in late afternoon. Vehicular surveys were conducted by driving 16.1 km/hr over the roads (9.5 km) through the bottomland twice per week. Pedestrian surveys were conducted on 6 sections of those roads (1.3, 1.3, 1.3, 1.1, 0.3, and 0.3 km), three on the larger main gravel road, and three sections on smaller dirt tributaries, twice weekly. One section of the main road (1.3 km) was located near three operat- ing oil rigs. The other 5 sections of the survey route traversed forested regions of the management area. The 3 sections located along the main gravel road were subject to regular vehicular traffi c by the public and OSBWMA staff. The three sections located along the dirt trail tributaries had primarily foot travel with much less and slower ve- hicular traffi c. GPS coordinate, date, and condition (alive or dead) of the specimens were recorded. In the summer, 10.5% of the amphibians and reptiles were found dead on the road (DOR). The number of DORs in the fall was 47.1%, and 64.3% in the spring. For amphibians, 28.1% were DOR (summer), 20% in the fall, and 83.3% in the spring. In the winter months, no specimens were observed on the roads. Road traffi c in this bottomland impacts reptiles extensively in the fall and amphibians in the summer, whereas both reptiles and amphibians are affected by road traffi c in the spring. Smaller roads and the section of road with oil rigs had lower mortality rates, while areas with adjacent borrow pits had higher mortality rates.