Burrowing Owls Athene cunicularia (Strigidae) respond with increased vigilance to calls of the Curl-crested Jay Cyanocorax cristatellus (Corvidae) in the Paraguayan Cerrado

Nesting Burrowing Owls ( Athene cunicularia) in the Cerrado of northeastern Paraguay were observed to show increased vigilance in response to Curl-crested Jay ( Cyanocorax cristatellus ) calls. To test whether this reaction was species specific, a playback experiment was conducted using jay calls, a native passerine and three exotic passerines, and responses of the owls to the recordings were measured. The results indicated that the owls responded with increased vigilance only to calls of the Curl-crested Jay. It is hypothesized that the interaction between the two species may be related to competition for dietary resources initiating a greater aggressive response in the diurnal jay due to its more limited foraging time, compared to the nocturnal and diurnal owls. The vigilant response of the owls may thus be related to avoidance of potentially costly aggressive interactions with jays.