Yesterday I noticed a carrion crow (Corvus corone corone) behaving rather strangely on the lawn at the front of our flats. It was sitting down in the grass with its wings slightly extended sideways, as if it was sunning itself -- but the Sun was not shining. I though it rather strange, but I had other things to do, so I soon forgot about it.
Well, today, what I presume was the same bird was doing exactly the same thing but in a slightly different spot. Then a car slowly drove past and the crow stood up and ambled further away from the road, waiting until the car was gone before returning to precisely the same patch of grass to sit down again. Then it occurred to me that I had often seen ants in the grass down there, so I went downstairs to take a closer look. Sure enough there was a concentration of ants in precisely the place where the crow had been sitting. Presumably, the crow was using these ants to de-louse itself.
When I came back in, the crow went back to the same spot to resume its ant-bath.
After observing the crow taking an ant-bath I started to think about
how such behaviour could have developed. How on earth did the
crow learn that sitting amongst ants was a good thing to do?
After all, sitting down in grass is not something that crows do very
often as part of their daily life, so they are not likely to have
stumbled across this behaviour by accident, and I would have thought
that their first reaction on seeing ants would be to eat them, not sit
Yesterday I realised that the obvious place that crows could sit amongst ants would be in the crow's nest. Ants might seek out birds nests as good sources of small parasitic insects and scraps of food and maybe the birds have learnt the benefits of the ants' presence, to the extent that when they see ants on the ground the idea occurs to them that it would be good to sit down among them. If this theory is correct then it would imply that ants must climb all the way up to crows' nests which are normally located in the tops of tall trees. Does any one know whether ants are commonly found in crows nests?
As I am typing this I can see a crow taking an 'ant bath' on the lawn
at the back of our flats. It has been there for the past 15
minutes at least.