One of the new MA students, Kaiya Provost is working with Dr. Brian Smith at the American Museum of Natural History. Kaiya is interested in bird phylogeography. As part of their work they use study skins, part of the collections at the museum. In this guest post, Kaiya talks about why these are important to her work and how one goes about making a study skin.
And now Kaiya…..
I have yet to meet someone who has never been to a Natural History museum. It is one of the standard class field trips that you would get overly excited about in primary and secondary school, because it meant getting out of European History. Even as a college kid those weekend-long trips to the American Museum of Natural History were something that you looked forward to. There isn’t anything quite like wandering through the Hall of African Mammals with a worksheet in hand, desperately trying to answer Question 7 (How many other species are in the Buffalo exhibit, and why do you think they are found in the same environments?) before you have to get back on the bus.
Teaching through museum exhibits is a great way to engage kids and get them away from the humdrum of the classroom, but it is only the very lucky school group that gets to see the museum from behind the scenes. As huge as the American Museum seems to a fifth grader, the sheer volume of space dedicated to research is even more astounding. In drawers and cabinets, millions of plants, animals, rocks, and historical artifacts are carefully preserved, waiting for an intrepid scientist to blaze a trail through the dusty halls and find them. These artifacts can be hundreds of years old, sitting carefully tucked away, holding within them the secrets of biology, history, anthropology and more.
It seems obvious that things such as bones, pots and other hardy materials might be able to be stored on a shelf for decades without much trouble. After all, we can find fossils in our backyard if we look hard enough! I myself have found old arrowheads, fossilized clams, and shark teeth just by exploring around parks and beaches. But, you might ask, how do you keep things preserved like the elephants in the AMNH’s Hall of Asian Mammals? Wouldn’t they, and other creatures, rot away?
Under normal circumstances, you’d be right. Indeed, the research specimens preserved in the bowels of the museum are constantly in danger of being eaten by scavenging bugs and beetles brought in from outside. But most of the tissue that would get particularly disgusting after years in a drawer is removed as the animal is being prepared for storage, and instead replaced with sawdust and cotton. Only the skin and bones remain.
I study birds, and as such preparing them for an eternity as a research specimen is an important skill for me and other ornithologists to have. Preserving them is a lengthy process, and one that requires great care, for they often have delicate skin and fragile bones. But the actual procedure itself is one that is simple.
To start, you need a collected bird. Many museum specimens come from birds that have been salvaged from roadkill or flying into windows, but more exotic specimens are occasionally gathered on collection trips to places such as the Amazon, Sahara, or Himalayas. These birds are temporarily stored on ice so that they don’t begin to degrade before they can be prepared.
When a bird is ready to be preserved, all of the information known about that bird is written down in a notebook. Sex, age, where it was caught, wing length, mass, and more are all recorded for the ages. This is later uploaded into a database that can be accessed by scientists around the world.
An incision is made into the outer later of the skin, from the bird’s sternum to it’s cloaca, the opening of the urinary, reproductive and digestive tracts. It is important that the body itself isn’t opened up, or the feathers could get wet with bodily fluids. To prevent this from happening, the bird is covered in sawdust. This absorbs the fluid and keeps the feathers looking pristine.
The skin is gently peeled back from the muscles, carefully working around the legs and wings and removing tissue along the way. The leg and wing bones are stripped of the muscles that allow them to move. Eventually, after hours of peeling skin, removing muscle, and dumping sawdust on the specimen, the skin is only attached to the head of the bird, resembling a sweater that has been turned inside out and gotten stuck.
At this point, the body cavity is finally opened to check the state of the internal organs. The bird is sexed by finding the ovaries or testes, and if the bird was in the process of breeding all of the developing eggs are counted. The stomach is opened to see what the bird was eating, and then a tissue sample is taken. The heart, liver, and breast muscles are all stored inside a labeled tube, which is then put into a freezer. These tissues can be used later in order to get DNA for scientific studies.
After all of this information has been recorded, the next step is to remove the parts of the skull that are not desired. All soft tissue is removed, but the beak and top of the cranium are kept with the skin. It wouldn’t look like much of a bird without a beak, after all! The skull itself is examined to check for pneumatization, or the complete formation of bone. Juvenile birds have skulls that are not completely intact, and so have windows that you can see through. As they mature, these windows close up and form into sturdy bone.
Now, the “sweater” of bird skin is carefully turned right-side out again. It is time for the bird to be stuffed with cotton!
First, cotton eyes are maneuvered up into the skull. This lets you see the beautiful and often intricate eye rings that some birds have, like MacGillivray’s Warbler. Then, cotton is wrapped around a dowel and lodged into the skull, serving as a replacement brain. Now, a large rolled-up piece of cotton is inserted to fill out the body, and two more are wrapped around the leg bones to replace the missing muscles.
Once the bird is properly stuffed, it is sewed up with string. The legs are tied together and the bird’s beak is glued shut. It is assigned a specific number, so that future researchers can find it, and then it is pinned to a board. Over the course of a few weeks, the specimen will dry out until it is ready to be placed into a drawer.
The American Museum of Natural History has over one million preserved birds, representing nearly all of the species of bird in existence today. They also have preserved eggs, skeletons, spread wings, and tissues. Only a fraction of these are out in the exhibits for the public to see. Museums will occasionally offer tours of the behind the scenes action, and I highly suggest that you check it out if you’re interested.
If you want to learn to skin, check with your local Natural History Museum, or even with your nearest university. Often they will offer classes to interested students, especially those who want to go into collections research. Not only will it get you very well-versed in bird anatomy, you’ll also contribute directly to further research by generating specimens and tissues to use!