red-shoulder hawk

This Red-Shoulder Hawk is a frequent visitor. He is sitting on the neighbors roof looking down in the grass probably for snakes. I don't know why he is standing like a flamingo with one leg tucked up. To date, I have never seen him get anything.

The species type has been verified by whatbird.com as a red-shoulder hawk.

Input regarding the folded leg was this, "could it be that he/she was trying to reduce the surface area of body touching the roof if the roof was especially hot or cold to avoid losing/gaining too much body heat?"

Here is what Cornell's All About Birds Site has to say about the one leg

54. Why is it standing on one leg?

It is perfectly normal for a hawk to stand on one leg while resting or roosting. They will sometimes alternate standing legs. They may do this as a heat-saving measure, keeping the raised leg warm against their stomachs, or as a way to reduce fatigue in the raised leg. Birds may also shift legs just to be more comfortable; in the same way a human will re-adjust their position!

source:  http://www.allaboutbirds.org/Page.aspx?pid=2607#2