Burrowing owls eavesdrop on southern lapwings' alarm calls to enhance their antipredatory behaviour.

Eavesdropping is a widespread behaviour among animals, providing the receiver with valuable information to assess the habitat, resources or threats. This kind of behaviour has been reported for the burrowing owl (Athene cunicularia), which in its northern range lives in close association with fossorial mammals and eavesdrops on their alarm calls as indicators of risk. In their southernmost range, burrowing owls do not associate with mammals, but they are often found sharing foraging and nesting patches with the southern lapwing (Vanellus chilensis), a noisy, territorial and aggressive plover species. We designed a field experimental study aimed at determining if burrowing owls are able to use lapwing calls as indicator of potential risk. We exposed focal owls to a sequence of sounds including lapwing alarm calls, and biological and non-biological controls, and registered their response as alert or relax behaviours. Linear mixed modeling showed that owls increased their alert behaviour in response to lapwing alarm calls but not in response to control treatments. In addition, owls' response was consistent between habitats (rural and urban) and seasons (breeding and non-breeding). Our results suggest that eavesdropping is a generalized strategy of burrowing owls to acquire environmental information throughout its distribution range.