Red-tailed Hawk Mystery Solved

A few days ago I posted a few cropped pictures of distant shots of a Red-tailed Hawk that had a strange shape to its neck...

The mystery shots - solved.

I had asked if anyone knew of the reason for it and got a number of responses.  As one of the responders put it, my "cropped" images were ironically named.  I got the answer to the mystery from a number of people  including one from Caleb, a 12 year old who is obviously a well informed, young birder! (see some of his pictures here).  Turns out that the "lump" in its throat was likely lunch sitting in its crop.  From notes provided by those readers and after researching the net a bit, the crop is a holding place before the bird's stomach which will slowly release food after eating a large meal.  The hawk may not eat again for days so the food is released slowly to be more efficiently digested rather than all the food going through the bird's system where not nearly as much of the food value would be absorbed.  A brilliant design feature for sure.

Thanks for the responses everyone.