I love goldfinches and I'm delighted that we have had two regularly and sometimes three of them this year. They seem to love the niger seeds.
I don't own any really long lenses so I stretched the 70-200 with the 1.4x extender and cropped heavily for this shot. I was pleased with the sharpness of the results despite the crop!
Canon EOS-1D Mark III, f/4 @ 280 mm, 1/1000, ISO 400