Research note: approach rather than avoidance: behavioral responses of broiler chicks repeatedly exposed to an...

Previous experience shapes animal behavior, and repeated exposure to non-aversive stimuli can reduce responses to subsequent challenges. Autonomous robots that navigate commercial broiler houses are being developed for environmental monitoring and have been shown to increase bird locomotion during their passage. However, whether this increased activity primarily reflects displacement or fear-induced avoidance, and how robot exposure influences behavioral responses, remains unclear. We assessed behavioral responses of broilers repeatedly exposed to the AviSense robot (Appelie Robotics) compared with non-exposed controls. From day 1 post-hatch, chicks were reared under commercial conditions in three 7.5 × 4.5 m pens containing approximately 500 birds each: one robot-exposed (RE) and two unexposed controls (CON). RE birds were exposed hourly to the robot for 10 min, whereas CON birds remained unexposed to it. At 13-15 d, chicks underwent individual behavioral tests; responses were analyzed with mixed-effects models. In a two-choice runway containing the robot and an unfamiliar basketball at opposite ends, RE chicks left the neutral zone sooner (P = 0.013) than controls. Treatment × Zone interaction P-values were 0.060 for latency to enter the stimulus close zones and 0.043 for time spent in these close zones. Fisher's LSD post hoc comparisons showed that RE chicks entered the robot close zone sooner than CON chicks (P = 0.004), spent more time in that zone than CON chicks (P = 0.004), and spent more time in the robot than the ball close zone (P = 0.036). In tests conducted without the robot, RE chicks showed shorter latency to ambulate in an open field (P = 0.002) and required more attempts to induce tonic immobility (P = 0.012), whereas social-reinstatement behavior was similar between treatments. Overall, previous robot exposure was associated with a robot-specific increase in subsequent proximity and with lower behavioral inhibition in independent fear-related contexts, providing no evidence that such exposure induced fear-driven avoidance. Repeated exposure to a robot may therefore promote familiarization and facilitate its integration into the birds' environment.