Combine all the layers, for your convenience, that finally form a bird’s wing. Copy the group’s layer. Using Free Transform option, turn it around, like in the next step.

Make use of the old instrument to represent the figure below.

And one more.

Keep connected now only those layers, that form the bird’s silhouette. Unite them (Ctrl + Shift +E) and we’ll get:

Use the next parameters indicated below
Blending Options-Gradient Overlay

Gradient’s parameters

We’ll get the next:

Connect the layer having the dark background, lighted a little in its center. Place out the bird’s silhouette above the mentioned layer.

Use Free Transform option to turn around the layer with the bird’s silhouette, like it is shown the next step.

The final result!