Anting (behavior)

Modes

Active anting

Anting most commonly occurs on the ground, with some species preferring tree branches. A bird will seize an ant with the beak and proceed to rub it over the feathers. However, there are some cases where an ant is used more than once but never exceeds three uses. There are some exceptions to this as starlings often take a ball of ants in their bills to be used for anting. Active anting happens very quickly and can often be mistaken for regular feather maintenance. This type of anting can last anywhere from just several minutes to half an hour. Most species of birds practice active anting and do this individually or in small groups. Birds may also use 'substitutes' to ants, such as snails, grasshoppers, amphipods and even larvae.

Passive anting

Passive anting is the practice of allowing ants to crawl freely across the body. The wings and tail are spread as flat as possible, allowing contact with the ground. Birds will typically shake ants from the head and neck. This type of anting is less common and is mostly seen in robins and ravens.

Functions

Ridding of ectoparasites

Anting to get rid of ectoparasites is one hypothesis for anting in songbirds. This hypothesis suggests that birds use the chemical secretions that come from ants to control and get rid of parasites in their feathers. Microorganisms such as bacteria and fungi can destroy a bird's feathers if their numbers become large enough. Formic acid is a commonly produced chemical by ants, and it was found to inhibit growth of feather-destroying microorganisms. However, there is little evidence that chemicals from ants help to remove or deter other parasites such as feather lice and mites.

Feather grooming

The hypothesis that anting is a form of feather maintenance suggests that anting brings saliva to the bird's feathers for use in preening. This helps to remove old preen oil and other substances.

Food preparation

The food preparation hypothesis suggests that birds rub the ant in its feathers to remove a substance on the ant. Ants produce formic acid as an anti-predator adaptation. Thus, when an ant feels threatened, as when in the beak of a bird, it will spray formic acid. It is suggested that birds then rub the ants in their feathers to remove the harmful formic acid. The bird will then ingest the ant. This can be seen in European starlings, Sturnus vulgaris.

Sensory self-stimulation

Anting has been compared to human activities such as smoking and other external stimuli that serve no biological purpose and are just for self-stimulation. This hypothesis has been suggested as anting has no obvious function, it is non-adaptive, birds are said to achieve pleasure from anting and anting has characteristics of a habit. However, there is no definitive evidence that sensory self-stimulation is the purpose of anting in birds. There have been several studies that claim to prove this hypothesis while others say the opposite.

Functions in molt

It has been found that passerine birds molt in the summer months. These birds often focus much of the anting on their wings and tails. This is where the largest feathers emerge, and it has been suggested that anting helps stimulate the growth of these feathers during molt. Not all birds that ant do so during molt.

Species of ants used

Ants that spray and produce formic acid for defense are used for anting more often than species which do not spray or produce formic acid. Species from the subfamily Formicinae are the most commonly chosen by birds. Species from Dolichoderinae and Myrmicinae subfamilies are also used for anting however, not as common as Formicinae. If given a choice a bird will choose an ant in the subfamily Formicinae over all other species. In total there are 24 ant species birds use for anting.

Substitutes of ants

Some birds participate in similar behaviour with other organisms, such as garlic snails, amphipods, millipedes, dermapterans, caterpillars, grasshoppers, hemipterans, mealworm larvae, and wasps.

Related behaviours

Dusting with soil from ant-hills has been considered by some as equivalent to anting.

Some birds like antbirds and flickers not only ant, but also consume the ants as an important part of their diet. Other opportunist ant-eating birds include sparrows, wrens, grouse and starlings. European honey-buzzards have been found to gather fresh maple branches on the ground and then spread themselves over it and it has been suggested that this might be a case of tool-use to attract ants for anting.

Similar to anting may be the observed habit some birds show of picking up cigarette butts, sometimes lit, and rubbing themselves with them.