We evaluated the effects offlow reduction and drying on prey availability and bat activity along a desertriver in southeastern Arizona. We sampled bat activity and insect availability during the dry season atperennial and intermittent sites along the San Pedro River. Intermittent sites included both temporallyflowing and dry conditions during the study period. Bat activity significantly declined between May andJune sampling periods but was not related to whether sites had perennial or intermittentflow. Declinesin bat activity corresponded to reductions in insect availability, but only at perennial sites. Bats trackedaquatic insect availability at perennial sites but not at intermittent sites, where insects appear to activelyaggregate above localized wet portions of the intermittent reaches. Finally, both bat and insect avail-ability declined to nearly undetected levels when the river dried at 2 of 16 sites in despite increases interrestrial insect availability. Our results indicate that intermittency affects bat activity indirectly via itseffects on prey availability. Seasonal river drying appears to have complex effects on foraging decisionsby bats, initially causing imperfect tracking by consumers of localized concentrations of resources, butlater resulting in disappearance of both insects and bats after complete drying.
Influence of river drying and insect availability on bat activity along the San Pedro River, Arizona (USA). Available from: https://www.researchgate.net/publication/256941331_Influence_of_river_drying_and_insect_availability_on_bat_activity_along_the_San_Pedro_River_Arizona_%28USA%29 [accessed Nov 11, 2015].