When birds try to clean up their act

By BILL CHAISSON
Of a Feather
I have pointed out in past columns the difference between birding and birdwatching. Birding is more of a sport, sometimes competitive, by which enthusiasts make an ever longer list of species seen (or heard), often by traveling to exotic places and getting up extremely early in the morning. Birdwatching, on the other hand, can be done without going anywhere at all (although getting up early is always a plus). You can be a decent birdwatcher if you put up bird feeders, bird houses, and plant shrubs and trees that attract birds to your yard.

Birdwatchers get to know individual birds because they see them day after day. They watch them fight with their neighbors, raise a family, and sometimes they have to wait for months while their resident birds spend the winter somewhere exotic, only to return in the spring and start fighting with their neighbors all over again.

If you watch the same birds day after day, you start to accumulate observations of different behaviors. One of the more unusual behaviors was originally described in 1935 by Erwin Streseman, a German ornithologist, who called it “Einemsen,” which translates into English as “anting.”

I first witnessed a mockingbird anting about 45 years ago. It is a strange sight. When you come upon an anting bird it is spread out awkwardly on the ground with its wings akimbo and its tail feathers spread. The nictitating membranes of the eyes may be closed, giving them a blank blue cast. Every so often the bird may quiver, making its feathers shake slightly. You will be forgiven for seeing this and wondering if the bird is injured, sick, or — more transgressively — on drugs.

What they are actually doing is an example of a broader class of animal behavior called “self anointing.” You have perhaps been told that it is not a good practice to pick up dead birds or collect their nests because they are infested with mites, lice, fungi, bacteria, and various other hitchhikers. This is the case with many animal species and many of them have evolved methods of applying chemicals to themselves to kill their vermin. Bears, for example, collect and masticate roots from Ligusticum porteri (variously called lovage, wild parsley, or bear root) and rub the chewed mass on their fur. The roots contain chemicals called coumarins, which have been shown to have anti-bacterial and anti-fungal properties.

Ants secrete formic acid as a defense against being eaten. Anting takes advantage of this defense by inviting the ants to crawl among the bird’s feathers until they reach the skin. The occasional shivering by the birds startles the ants and causes them to release formic acid to repel a perceived attack. The acid kills any mites, lice, fungi, or even bacteria that happen to be near the ants on the bird.

Some birds engage in what is called “active anting”; they will pick up an individual insect and rub it over their feathers. Being clasped in the bird’s beak is probably enough to set off the defensive reaction but being crushed likely manually releases the formic acid from the sacs in the ant. Experiments have been done using ants with empty formic acid sacs and these insects do not induce the anting behavior in birds.

It has been many years since I have witnessed birds anting. Yesterday I looked out the window of my office (after being summoned by a baffled town administrator) to see three robins sprawled in the characteristic posture along the edge of a clearing. It is very sandy where I work in Wilmot Flat; it is the beach of a former post-glacial lake and this is not ideal ant territory. But the robins were sprawled on the lawn beneath white pines and some deciduous trees. Apparently enough organic matter had accumulated to build a decent soil structure and had allowed the ants to build their tunnels.

It is a little counter-intuitive that ants do not like sand in that when you encounter an anthill it seems to be made up largely of sand grains. But remember that the ants are removing the sand grains in the process of building their colony of tunnels. If the substrate were entirely made of sand grains it would not support a tunnel; it would simply collapse as the grains slide past each other. You experience this quality of sand when you try to walk on it at the beach and sink in with each footstep.

I have not seen birds engage in anting on an anthill, nor have I seen any photographs of them doing so. I would guess that there might be too many ants right on a hill. Instead of getting pleasingly doused with formic acid, the birds would get uncomfortably bitten a little too often.

The above explanation for anting is not classified as established fact. There may be other reasons for anting. Some birds, blue jays in particular, have been observed eating the ants during the anting episodes, which has led to speculation that the behavior is a way of draining the unpleasant formic acid out of a meal. Birds also use millipedes and push moth caterpillars in self-anointing behavior, as both also secrete defensive chemicals.

Other bird scientists have noted that anting is most often observed this time of year and therefore might be related to molting. Certainly, birds this time of year are looking a little ragged. Birds generally molt twice each year, once before each leg of migration (or in non-migrant birds, before and after breeding, which involves similar timing). Many birds are now either done with breeding or are winding down that leg of their annual cycle. Their feathers have taken a beating: first during migration, then during any combat they might have engaged in while defending their territories, and also from simple wear and tear over the months of being nibbled upon and distressed by their arthropod and fungal passengers. Some have therefore speculated that anting is analogous to having a little body work done on your older car; you can’t really stop the corrosion, but you can slow it down.

Whatever its purpose anting is fascinating to watch. Bird species all over the world engage in the same behavior, not just songbirds, but raptors, fowl and other types as well. And again, it is part of a class of self-anointing behaviors practiced by many animals. The counterpart among humans would be herbal medicine or use of leeches. These may be thought of as somewhat marginal practices in the modern world, but nevertheless have been normal healing methodologies for thousands of years in many cultures. I’m not aware of anting being practiced by any human cultures (aside from the eating part), but apparently the Navajo were observant enough to learn about the medicinal properties of wild parsley by paying attention to bears.

Bill Chaisson is the former editor of the Eagle Times and now the property and land use assistant for the Town of Wilmot.