Food distribution and availability fundamentally shape foraging. Yet spatiotemporal distribution of mobile prey and its proximate effects on animals have rarely been assessed. The neotropical bat, Noctilio albiventris, forages on aquatic swarming insects which peak just one to two hours after dusk. We matched seasonal insect distribution at high spatiotemporal resolution to the foraging behavior of adult female bats. Surprisingly, insect abundance was lower in the wet season, and insect patches dispersed more rapidly. Correspondingly, bats emerged 45% earlier, foraged over 40% longer, and flew almost twice as far compared to the dry season. Wet season bats also spent less time at each patch, suggesting that patches, though the same size, were less dense and depleted more rapidly. Our results highlight the tight link between foraging and sharp seasonal shifts in the spatial unpredictability and temporal ephemerality of resources, shedding light on behavioral adaptations and plasticity in response to resource fluctuation.