Influence of Surface Area, Water Level and Adjacent Vegetation on Bat Use of Artificial Water Sources

Abstract

Reliable natural water sources often are unavailable for bats in semi-arid regions such as the Texas Panhandle. Metal stock tanks commonly are used to supply water to livestock and are used by bats as a water source. It is unknown how surface area, water level and adjacent vegetation influence use of tanks by bats. Infrared video cameras and supplemental infrared lights were used to video tape bat behavior and use of stock tanks in Palo Duro Canyon State Park, Texas. Treatment tanks were set out in pairs approximately 80 m apart in a cross-over design to account for influence of location on use of tanks by bats. Treatments included three sizes of tanks (1.2 m, 1.8 m and 3.0 m in diameter), three levels of cover of adjacent vegetation (no vegetation, light vegetation and heavy vegetation) and two water levels (full and ½ full). The number of bats that passed over 3.0 m and 1.2 m tanks was similar; however, bats drank from large tanks more than small tanks. Passes were similar between the tanks surrounded by light vegetation and tanks with no vegetation, but bats drank more from tanks surrounded by light vegetation. Tanks surrounded by heavy vegetation experienced fewer passes and fewer drinks than tanks without vegetation. Water level had no effect on the number of passes by bats but ½ full tanks were used for drinking less frequently than full tanks. Our research indicates that size of tank, water level in tanks and characteristics of adjacent vegetation influence use of metal livestock tanks by bats. Use of larger tanks, keeping tanks full and managing vegetation around tanks increases use of tanks by bats.