On my Seagulls skin, Deepstraz recommended experimenting with other textures to fit the bird doodad. I did play around a bit more, and ended up making not a bird skin based on any other Warcraft creature, but a bat texture! A more realistic one. Since the birds doodad and bats doodad use the same texture, you can also use the birds as bats, they'll have visible legs and move a bit differently but still look like bat. However, the way the bats doodad works is that it's darkened by a geoset animation. I've included an edited model of the bats that has the geoset animation colour set to white so that you can see the texture. That is the doodad that I have used to provide the screenshots.

The skin is almost all freehand but I copied and edited the wing from a drawing I found online, and I based the colours of the rest of the bat on that art. I was not able to find an author, but here is a link to the art online.

Credit is appreciated but not required.