The light is just too dang low.
Guess I'll just have to wait for the next really sunny day...probably some time in, oh, April!
I did manage to accidentally catch this image of a northern shrike when it landed 35 feet from me in the sumac. Since it's a 'mini-hawk' in behavior, I had one glorious instant surrounded by the sound of alarm chips and whirring wings as a mixed flock of 150 small birds went up from under the feeders all at once!
Shutter speed of 1/800; ISO bumped up to 640. It's still pretty dark, but not too bad for a serendipitous shot of an uncommon bird.
Missed it's take off, though, so blew the opportunity to find out if 1/800 will freeze moving shrike wings.