CJ Crawford (Yahoo!, Panasonic forum, 10th January 2004)...
I shoot through the window. I set up a tripod and pre-focus the camera, then stand there and wait. Eventually the birds lose their fear of the strange object they see -- if they see me. Sometimes, in the {morning} the reflections are such that they cannot see in very well, so if I don't move much they aren't alarmed. Wish the FZ10 had a remote so I didn't have to stand there with my finger on the button {the FZ20 does have a remote...} ... luckily, we have tons of birds fighting for position.
Auto contrast, or contrast/brightness {post-processing tools in Photoshop} seems to get rid of that bit of dullness that shooting through windows can create. Shadow/highlight can sometimes make things look a bit artificial -- I tend to tone it down quite a bit.
{Cindy's photo-gallery has a wide range of subject matter, not just birds. Other than the photographs, you can also have a look at her watercolours!}