<P> Male grey catbirds fluff their feathers and spread their lower tails to defend their territory when threatened by another male . The bird that is capable of puffing up and appearing to be the biggest will win the territory . </P> <P> Male western gorillas display a wide range of both vocal and gestural communications when threatened by an opponent . A silverback (alpha male) will start hooting, throwing, chest pounding, leg kicks, and sideways running when approached by another male . This is done to intimidate the opponent and show physical abilities without actually making any physical contact . </P> <P> Threat behaviour is any behaviour that signifies hostility or intent to attack another animal . Threat behaviour is meant to cause the opponent to back down and leave . While ritual display can be used for an array of reasons or communicative purposes, threat distinctly is meant for hostility and is the last step before fighting or submission . Threat does not involve physical contact with another animal . Any threat behaviour most often elicits other agonistic behaviour in the recipient . This initiation of threat will result in a display of physical attributes, a fight, or submission; the behaviour or sequence of behaviours depends on what resources are being fought over and each individual's chance of winning against his opponent . In any animal species, threat always contains components of attack and fleeing, which expresses an animal's readiness and likelihood of winning . An intimidation display with a means to threat are exhibited through: hair bristling, feather ruffling, raising skin folds and crest, teeth displaying, horn displaying, making sound, etc . </P> <P> Chlamydosaurus kingii, an Australian agamid lizard, uses its frill as a way to display size and aggression to opponents . It is one of the largest and most notable displays seen in the animal kingdom . In comparison to its body size, the frill can flare out to make the lizards head look several times bigger, and it displays bright orange and red scales . Males of C. kinggi fight and display frills often during the mating seasons . The male ritualistic display includes repeated partial erections of the frill, head bobbing, tail lashing, and waving of forelimbs . </P>

Name several animals that engage in damaging fights