Very interesting. The OOF reeds in front of the focus plane make it look almost as if the image was panned vertically during the exposure while somehow maintaining a sharp focus on the bird.
If their hadn't been a reed in front of the birds abdomen and tail, it would have been even stronger.
The image caused me to study it carefully, which is always a good thing!
I do love the light, it's dramatic and adds a lot to the image. Too bad about the OOF reed in front of the abdomen, would have liked to see more of a head turn towards the camera. Sweet little bird.