Bats are potentially exposed to pesticides by eating contaminated insects in croplands. Commonly used pesticides such as organophosphates (OPs) are neurotoxic for non-target vertebrate species and even low doses can impair essential processes such as locomotion and cognition. These neurotoxic effects are usually sublethal and can therefore be difficult to study using traditional toxicological assessments. Behavioral studies are a promising alternative to evaluate sublethal effects on bats. Echolocating bats usually develop individual stereotyped flight patterns as they become familiar with a novel space. We evaluated bats’ ability to memorize and navigate a new space by comparing the consistency of these repetitive trajectories between exposed and unexposed bats. We orally dosed captive big brown bats (Eptesicus fuscus) with an environmentally relevant concentration of Chlorpyrifos, a commonly used insecticide. We tracked their flight behavior while exploring a flight tent. We evaluated the similarity in their trajectories within and among trials, time spent in flight, and landing frequency. We also quantified the ChE activity in brain and plasma as a biomarker of the potential mechanism of neurotoxicity. Preliminary results suggest an increase in the variability of the trajectory in exposed bats within trials, and an increase in landing frequency compared to unexposed bats. Exposed bats presented a 60% reduction of the brain ChE activity. These results support the sensitivity of behavior as a biomarker of toxicity and as a tool to elucidate potential ecological implications of anthropogenic stressors on wildlife.