No, this isn’t about our insect friends. It’s about bird behavior that has mystified me for years. I think I got it figured out.
I’ve always had water baths for birds and other backyard critters, and toyed with setting up a bird dust bath. But I never got around to it. I see lots of areas in the neighborhood, where the grass is thin or nonexistent, with the telltale bird-belly sized divots. So my feathered friends are not lacking for dust bathing opportunities.
But I’ve noticed for years that, once in awhile, a bird has nestled down in the backyard as if to take a dust bath. The problem is, we have perennial flower beds and woodchip paths. No dust that I can see (outside, that is). The birds hunker down, belly to the ground, wings spread out on the ground, and sometimes with their head twisted up at an odd angle. The first bird I saw doing this was a Robin that appeared much like the title photo. I thought it was dead. Or at least in mortal distress. It was not and flew off at my approach.
A search on the Intertubes promptly came up with anting. A Wild Bird Scoop article describes the basics.
Ants, as well as other insects secrete a liquid which contains chemicals. One of the chemicals that ants secrete is formic acid and may be of benefit to the birds.
. . . .
When a feathered friend feels the need to rid themselves of some pests they will find a dry, safe spot where there are many ants in the area and stand in the midst of the insects and allow them to crawl on their body.
Wild birds have also been observed rolling on top of an ant hill to crush them or picking them up in their bill and then rubbing the insect on their feathers.
Another article goes into more detail.
More than 200 species of birds have been recorded displaying this [anting] behaviour.
There are two kinds of anting – passive and active. Passive anting is when the bird finds an ant nest, and then lies down on the nest sand, allowing the ants to crawl onto its feathers. After a sufficient number of ants climb onto the bird, it will shake its feathers causing the ants to secrete formic acid. Once the ants have discharged their acid, the bird may eat them. It is possible that the acid may also act as an insecticide or fungicide, but there is no real scientific evidence of this.
During active anting the bird will actually pick up the ants and wipe them over its plumage. Once the stroking is complete and the ants have discharged their acid, the ants are either eaten, or thrown away.
Anting and dustbathing are equally efficient methods of removing parasites, but anting is far less common, and is one of the more unique behaviours in the animal world.
For a deep dive, here’s a 22-page scholarly paper out of the University of New Mexico by Eloise F. Potter. Based on the 1970 date of this paper, the theorizing about why birds ant has been around for quite awhile, but it’s new to me. A new laptop + retirement = time to start sorting through the mess that is my digital photo library. Seeing these old Robin photos retriggered my curiosity. Curiosity + retirement = time to actually pull on that thread and figure out what the birds may be up to.
Anting makes sense, given the nature of our backyard. The subsoil in our part of the Detroit suburbs is sand, deposited by glaciers. We have only a small patch of grass in the backyard for the dog, and the rest is garden.
With the sandy soil, no grass, wood chips and a good measure of landscape rocks and bricks, we have lots of ants. There’s no danger (yet) this far north for fire ants, so we leave them be. More of nature’s bird food in my mind. Based on the articles and the specific location of the behavior in the yard, my visiting birds are passive anting. I know now to look a little closer to see if they are active anting as well.
Now It’s Your Turn.
What have you noted happening in your area or travels. As usual, post your observations as well as their general location in the comments. Thanks for stopping by.