Red-headed vulture skull

Also known as King vulture, or Sarcogyps calvus.

A pretty fun one to draw with all the intertwining volumes and surfaces.

As usual, done on an iPad 2, with Sketchbook Pro, and a Wacom Bamboo stylus.

You should check it in big, as it features the version with the shadow layer.

And there's the rest of the series, obviously.