Latest customer at the Scholz Spa
That spot is a favorite hang out of the cardinals, robins and finches, who behave exactly the same. They sit there with wings extended for several minutes.
I've also seen our little wild rabbit roll around on the earth there.
A squirrel did the same thing on a similar patch on the other side of the yard.
Is there a zoologist in the blogosphere?
My theory: I saw a special on some (african I think) ants that would spray acid at threats. Birds (and lizards I think) would harass these little ants to incite them to spray them with the acid that would allegedly kill (or otherwise offer relief from) tiny mites or ticks or something.
Now, I don't think we have acid spewing ants, but I wouldn't be terribly surprised if the dirt was very acidic. Would having a dirt bath there have a similar effect? Anyone?