Anting is a behaviour of birds that involves rubbing insects, usually ants on their skin and feathers. The first reports of this behaviour come from the early 19th century when James Audubon recorded juvenile turkeys wallowing in ant hills. Anting has now been recorded in all but one continent and in over 200 bird species, it is thought that the fact that birds use ants that secrete formic acid or other pungent substances may mean this behaviour is a form of parasite control.
In active anting birds take an ant in their beak, crush it and directly rub it through their plumage. Active anting happens very quickly where a bird takes an ant in its bill and rubs one feather with one ant at a time, this often appears to the onlooker as just regular preening.
Other objects have been used for active anting, both living things such as caterpillars and wasps. Birds will also anoint themselves with non living substances such as leaves or lime juice.
Passive anting involves birds provoking ants to attack them by visiting ant colonies. Birds will lie and performing dust bathing type activities on the ground whilst allowing the ants to move through their feathers. This type of anting is less common and is mostly seen in robins and ravens.
Why do birds practice anting?
Ants will spray or exude formic acid as a form of defense or attack and it is the basis of this that leads to many of the hypotheses for why birds take part in anting behaviour. It has been noted that birds will more often than not choose ants from the family formicinae which spray and produce formic acid as a form of defence.
It is suggested that the secretions from ants may help to deter ectoparasites in birds feathers, however there is little evidence that formic acid does help control of feather mites and lice. Formic acid does however inhibit the growth of microorganisms such as fungi and bacteria that can damage feathers if present in large numbers, however it has not been demonstrated that there is a high enough concentration of formic acid on feathers to have bactericidal or fungicidal effects.
Some birds have been seen rubbing lime juice through their feathers and it has been shown lime rind is lethal to pigeon lice and toxic to cat fleas. Citronella and other citrus components are known to repel lice and other external parasites.
Anting may bring saliva to a birds feather as a way of removing old preen oil and other substances in order to maintain good feather condition.
This behaviour may allow the removal of formic acid and other pungent chemicals from ants before the birds eat them.
Some have suggested that birds may enjoy this behaviour and it may form some sort of habit that has no biological function but brings the birds pleasure, a bit like smoking in humans.
Stimulation of feather growth in molt
Most of the birds that show anting behaviour are passserines, these molt in the summer months and it has been suggested that it may help the development of large feather growth as this is where the behavioiur seems to be focused.
Convincing support for any of the hypotheses mentioned is still documented as studies that may prove these theories to be true or false are difficult to conduct.
It is fascinating to watch bird behaviour wherever you are, in your garden or at the park. Next time you see your garden birds preening and sunbathing, they might just be anting!