Great-crested Flycatcher - Myiarchus crinitus
August 29, 2011
Hello - it's time for your Monday morning study skin lesson. Last week at the Field I was able to work on a beautiful specimen of a Great-crested Flycatcher; a bird that I have never seen before, neither in the prep lab or while bird watching. As flycatchers go it's quite large. As you can see, its breast is a beautiful light, lemon yellow, and it has long sienna brown tail feathers. I was sad to see it in the lab as it was a window kill, but I was excited to have an opportunity to study up close such an amazing species.
Last week I posted a couple of photos of a Rose-breasted Grosbeak that I had made in to a study skin, and thought that I would provide a few more process photos this time around. At this point, I am generally able to identify what I am working on, but in this case I didn't recognize the species and had to look it up in a guide. All specimens have a tag tied to their feet with a number, its scientific name, and the date it was collected.
The second photo shows what the bird looks like right before it is stuffed. I have removed everything except for the skull, wing bones, and leg bones. The skin has been cleaned of any fat and blood (usually there is little) with some sawdust. The larger piece of cotton will replace its body, with the thin part threading up through its neck and out the beak. The q-tip looking dowel will lend some support to the neck. The cotton end will be gently pushed up in to the skull, and this will also aid in keeping the eye cotton in place. Once all of the cotton is in place, then I sew up along the breast. This was the first (and only) incision I made to skin the bird.
Once sewn up, legs are tied together, and beak is tied shut. Some of the info that is included on the new tag: who the skin was prepared by (me!), sex (m), amount of body fat (low), tissue taken (yes), size and type of gonads (4 x 7 mm, testes), and skull ossification (100%). We only note skull ossification in passerine species. In the case of my flycatcher, the skull was fully ossified. This means that when I looked at it after removing the brain, a fine stippling pattern could be seen throughout the bone. This indicates that it is an adult bird. If I was working on something like a waterfowl, hawk, or an owl, ossification would not be relevant as their skulls develop differently.
The final step is to then pin out the bird to dry for a couple of weeks. I find that this is sometimes the most challenging part, and can determine a beautifully done study skin. The actual skinning can be challenging, depending on your skill level and the species on which you work. Bird skin varies greatly in strength from species to species. Robins and nightjars have infuriatingly delicate skin; tearing if you glance at them. Hummingbirds, on the other hand, have shockingly tough and elastic skin. But once the skinning is complete, there is the matter of putting feathers back in place and to make the bird look as natural as possible. I could spend twice the amount of time fussing and fidgeting with smoothing and positioning feathers compared to what I spend on the actual skinning. An experienced skinner will have developed an understanding of anatomy and feather placement, and it always shows in the final resulting specimen.
Well, I think this post is long enough! I hope to have time to do a watercolor of this fellow this week. We'll see. If I do, I'll be sure to post it.