What are the robins doing?

It is Labor Day (September 5) in central Indiana. It is warm (85 degrees) and perfectly sunny. There is a very nice spread of grass behind my house and my neighbors’, protected on all sides by the houses, the woods, and a hedge. Skittish wildlife likes to hang out on this little green–about four bunnies graze on it every evening, and there are tons and tons of birds that live in the woods and like to play in the unmowed grass.

But today, the robins are doing something very strange. They are fluffing out their feathers and spreading themselves out on the grass. Then they lie very, very still for a very, very long time. Eventually they snap out of it and dart back into the woods. But while they’re spread out on the grass, they are deathly still; in fact I took notice because I saw one of them out there and thought “cleanup on aisle 3.”

The robins don’t even move when the neighbor’s dachsund was let out for a run-around and actually sniffed one.

What on EARTH are they doing? I think that both males and females are doing it.

They may be just sunning, or they may be “anting,” a behavior in which birds lay down on anthills and allow ants to run over their bodies. Both behaviors are generally thought to be related to getting rid of feather parasites or other pests.

More on these behaviors can be found here