By now most birdwatchers and photographers are aware of anting. This is where certain birds make use of ants to get rid of lice found in their feathers. Ants are mostly used because they spray formic acid as a defence mechanism to subdue their prey. Picking up ants and rubbing them along the feathers will cause them to discharge formic acid. Birds also use millipedes as these have also been known to use chemicals against their enemies LINK. We have also documented woodpeckers pecking at the tree trunk to get at the sap for the same purpose LINK 1 and LINK 2.
If you are eager to witness anting, keep a close watch on the Javan Myna (Acridotheres javanicus). This is one of the most common birds in Singapore and chances are that you may be rewarded with seeing this behaviour LINK. Anting is also common among crows but these birds are now uncommon as they have been culled because they mess around with our garbage. Crows are interesting as they are involved in active as well as passive anting. Passive anting involves lying on an ant nest to allow the ants to swarm over them LINK.
Laughingthrushes also ant LINK (see video above, courtesy of Dr Leong Tzi Ming) as well as a number of other Passerines, but they have yet to be documented locally.
In active anting, the bird picks up the ant and places it on the outer flight feathers. Less frequently the ant may be placed under the tail, on the outer tail feathers. These birds very seldom place the ant on their body. Usually, the ant is picked up with the tip of the bill. The bird then strokes the ant down on the underside of the extended wing, moving from near the base of the feather to the tip. One primary feather is treated at a time. Attention is then given to the other wing or the bird may alternate from one wing to the other. The tail is then dealt with.
During anting the bird half closes the eyes and the nictitating membrane may then flick across the eye (above). This probably protects the eyes from the ant’s formic acid and against contact with the feathers.
The ants may be used singly or several at a time. Some birds crush the ant so that the acid-glands are ruptured, others use the ants intact. Most birds bite the ant and use it immediately although a few may nibble it first. The ants may be eaten or discarded after use.
So, is anting innate or acquired by learning? Ornithologists tend to agree that anting is innate, the behaviour being hard-wired into the bird’s DNA. However, it is possible that such behaviour needs to be learnt by observing others in order to perfect it through trial and error. How else do you explain birds picking up non-worker ants that do not produce formic acid to ant? Or use tobacco ash, lighted cigarette butts, mothballs, small limes and various insects to ant as reported in the literature? Or can these items actually get rid of lice?
2nd April 2018
Simmons, KEL 1957. A review of the anting-behaviour of Passerine birds. British Birds. Vol. L No. 10, 401-430 PDF.