Most bats depend strongly on surface water to survive and reproduce, and thus it is a limiting resource in markedly seasonal environments, such as semiarid and temperate Mexico. Cattle ranching, an important activity in these areas has resulted in construction of rainwater reservoirs that may represent the only available surface water during the dry season. Using acoustic detectors we measured activity in cattle ponds at La Michilía Biosphere Reserve, Durango, Mexico to assess patterns of use by insectivorous bats. We tested for differences in activity between ponds and seasons, and for relationships between bat activity and a set of environmental and pond variables. Bat activity was significantly higher at ponds in the dry season; ponds were used by aerial, trawling, and gleaning insectivores. In the rainy season gleaners did not use ponds, and the other guilds used them less frequently. Larger, older ponds with aquatic vegetation were used more frequently in the dry season, whereas maximum temperature and moon phase affected use in the rainy season. Cattle ponds are common in rangelands and forests of northern Mexico; they constitute important foraging and drinking resources in an area that harbors the largest populations of insectivorous bats in the world.