Habituation as a mechanism of reduced aggression between neighboring territorial male bullfrogs (Rana catesbeiana)

Territorial animals often exhibit relatively lower levels of aggression tow ard familiar territorial neighbors than toward strangers. Habituation to a neighbor or its communication signals has been proposed to account for this reduced aggression between adjacent territorial neighbors. The authors ask ed whether discrimination between neighbors and strangers by territorial ma le bullfrogs (Rana catesbeiana) could result from habituation of the aggres sive response to repeated presentations of the acoustic communication signa ls of a simulated new neighbor calling from an adjacent territory. In 3 fie ld playback experiments, the authors found evidence for 5 response characte ristics that operationally define habituation. Moreover, aggressive respons e decrements persisted between nights of chorusing and were specific to an individually distinct property of male advertisement calls. The authors sug gest that reduced aggression between neighboring territorial male bullfrogs could result from long-term, stimulus-specific habituation to the advertis ement calls of a new neighbor.