Avian Anatomy for Artists: The Skull

Jul 27, 2020
American Robin skull. Ink on paper. 2020

Traditionally, human figure drawing includes the study of skeletal features. This knowledge gives the artist much more freedom to depict their subject in ways that are natural and accurate.

In this post, I’ll introduce you to some of the features of a bird’s skull that might help you to portray your birds more skillfully.

There are many features that make bird skulls unique. As artists, some of the most important aspects are:

  • The brain case is proportionally very small (hence the origin of the insult “bird brained”).
  • The eye socket takes up roughly half of the volume of the skull and the eye itself contains a special bone called a sclerotic ring. The orientation of the sclerotic ring relative to the skull greatly affects the appearance of the eye.
  • The lower portion of the bill is joined to the lower mandible and hinges from a point below and posterior to the visible portion of the eye.
Photo credit: Wikimedia Commons. Overlay drawing by the author.

In the figure above, you’ll see an overlay of a simple outline of an American Robin’s skull with the bird’s head for comparison.

The first thing you might notice is how little of the head is accounted for by the skull! The rest is musculature and feathers. If you look closely, you can see the roundness of the skull by the contours of the feathers themselves.

I’ve hypothesized the location and shape of the sclerotic ring (in red), which floats outside the orbital cavity, forming a protective region around the exposed portion of the eye. To get a better idea of what that floating ring looks like, take a look at this 3D model of a Black Vulture skull. (As an aside, I’ve yet to find a good model of a passerine skull that includes the sclerotic ring, which apparently is rarely included when specimens are prepared.)

The lower mandible is outlined in blue to help distinguish it from the from the upper portion of the skull.

To study more bird skulls, visit Skullsite.

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