we probably will not thought of using this lens and camera combination for birding shots..
But on a recent trip to China, was lucky to see a nest at the ceiling of the house.
So managed to get some images of the birds
Even when the reach is not enough, we can still crop the image
As seen in this image, before it was cropped, and after it was cropped.
Some other images here
These few images were shot at iso 6400 due to the very bad lighting in the ceiling..