The gnatcatcher and the caterpillar...

While I sat in the grass watching a Red-shouldered Hawk's nest, this Blue-gray Gnatcatcher landed on a branch in a tree very close to me. I had been sitting still for a while, so maybe he didn't notice me, or maybe the promise of tasty crawly eats overrode the danger of a human with a camera...

This Blue-gray Gnatcatcher was studying something on a branch above him. I knew whatever it was had to be important because the little bird had come in so close to me. I wondered what it was and imagined a fat and juicy caterpillar inching along unaware of its impending doom...

...sure enough, the male gnatcatcher snatched up the protein-rich larva right in front of me!  The instant I clicked the shutter, he glanced my way, warning me off the tasty treat with a birdy (but steely) stink eye... 

Yum...fresh caterpillar...

...hmmmm...is that another?

...it definitely was, and within seconds, he jumped to the next branch over and nabbed another unsuspecting caterpillar. 

How do you tell a male Blue-gray Gnatcatcher from a female? 
Just look for "eyebrows." During the breeding season when males are in their alternate breeding plumage, you'll see a thick, black line above their eyes:

Male Blue-gray Gnatcatchers in breeding plumage sport dark eyebrows!