Why do animals fight? When do they avoid it?
Conflict is very common in the animal kingdom. In many cases conflict between animals is resolved by displaying and actual fighting is avoided, but there are also many examples of fighting, some of which end up in the death of the opponent. From observations of animal conflict it is clear that some circumstances are more conductive to fighting than others, that animals do not always fight when given the opportunity and that individuals vary in the readiness with which they resort to fighting. Such differences in agonistic behaviour often reflect an animal’s chances of winning or getting injured and the importance of the issue concerned. I am going to examine why animals fight and when they avoid it.
The benefits of displays or fighting are quite obvious in many cases. The winner(s) can gain exclusive use of a resource such as a food source or may obtain exclusive mating rights whereas losers gain either nothing or only partial access. The more aggressive an animal is, the more benefits it is likely to gain, but if an animal is too aggressive it might face unacceptably high costs, such as serious injury, so the animal must weigh up the relative costs and benefits of its action and choose an optimum level of aggression. If the costs are too high and the benefits too low, avoiding a fight may be preferable to competing. In other cases it may be worth fighting vigorously for a valuable resource.
In many cases animal conflict is concerned with territories. In the Sonoran desert botfly males defend adjacent territories on the top of a ridge, chasing away rivals and mating with any females that arrive. This type of territory, used only for mating and containing no resource required by either the male or female, is known as lek. In social insects the colony, and sometimes a feeding territory around it, is defended from conspecifics and other intruders. African weaver ants fight fiercely and frequently and they produce colony-specific chemicals which help to recruit more ants when intruders are discovered; the intruders are killed and eaten. These two examples clearly show that territorial defence takes place for different reasons i.e. because different kinds of “resources” are valued by the animals concerned. An example of conflict over food sources are oystercatchers who feed in flocks on mussel beds in winter. Aggressive attacks, usually over mussels, consists of a lunge with the bill held horizontally, occasionally with wings flapping. Sometimes a bird stabs its bill at another or even grabs at a wing or tail. Attackers manage to steal the mussel only 21% of the time, however. Some individuals are more aggressive than others, feed in the best areas and are more successful at stealing. Immature birds are less aggressive, less successful and are displaced from the best mussels. Agonistic encounters can take place within groups of animals without actually being about a particular resource, but in order to establish a dominance hierarchy which is of course linked to resources. In a troop of rhesus monkeys, both males and females have a dominance structure, with some high status animals being deferred to by the entire group and, at the other extreme, low status animals deferring to all others. The nature of this hierarchy is complex, however, since two or more animals (relatives or animals or adjacent rank) often co-operate to defeat an opponent of higher status. These complications make the outcome of aggressive encounters between two particular individuals less than predictable, since even the top ranking male may be forced to retreat in certain conditions. The examples above show that animals may fight or at least engage in agonistic behaviours for very different reasons.
- Quote paper
- BA (Oxon), Dip Psych (Open) Christine Langhoff (Author), 2003, Why do animals fight? When do they avoid it?, Munich, GRIN Verlag, https://www.grin.com/document/13244