 In frogs , male territorial behaviour is often observed at breeding locations ; calling is both an announcement of ownership of part of this resource and an advertisement call to potential mates . In general , a deeper voice represents a heavier and more powerful individual , and this may be sufficient to prevent intrusion by smaller males . Much energy is used in the vocalization and it takes a toll on the territory holder who may be displaced by a fitter rival if he tires . There is a tendency for males to tolerate the holders of neighbouring territories while vigorously attacking unknown intruders . Holders of territories have a " home advantage " and usually come off better in an encounter between two similar @-@ sized frogs . If threats are insufficient , chest to chest tussles may take place . Fighting methods include pushing and shoving , deflating the opponent 's vocal sac , seizing him by the head , jumping on his back , biting , chasing , splashing , and ducking him under the water . 
