Shooting through glass? (1 Viewer)

I have a window mounted hummingbird feeder. I've been able to get some pretty fine photos with a tripod and natural light, but I'm really wishing for some sharper images with more color. In order to do that, I need to shoot on an aperture stopped down, which means I need some flash.

I've done some looking online and seen a few setups outside. Since I live in an apartment with some not-so-nice neighbors, I can't put a bunch of speedlights outside because they'd be walked off with really fast. Obviously, flash through a window is hit-or-miss. What can I do to minimize flash blowback and still light the hummingbirds so that the flash makes the feathers show as iridescent?

Basically you need to get as close to the window as possible to avoid any glare being reflected back from the glass.