By Jennifer A. Sheridan
Last week the amphibian and reptile unit acquired a valuable specimen—a timber rattlesnake (Crotalus horridus). This species is federally protected, and females can take up to 10 years to reach sexual maturity. This long time to maturity means that they are particularly vulnerable to population declines, so for this and other reasons we would never harvest a live one. Fresh roadkills, however, while sad, are valuable to our collection and the collective database on rattlesnakes. This was found dead in the road at Powdermill Nature Reserve, so I brought it back to the museum to fix in formalin.
The formalin helps to harden the tissues so that they maintain a shape in long-term storage that is conducive to future morphological study. After about two weeks, the curatorial assistant, Kaylin Martin, will soak the specimen in water to remove as much formalin as possible (leaving it in formalin too long can make the specimen difficult to handle for future studies), and then transfer it to gradually stronger ethanol for long-term storage. Amphibian and reptile specimens are stored in ethanol (hence the name of our home, the Alcohol House) to prevent them from decaying over time.
This particular specimen brings our total number of C. horridus at Carnegie Museum of Natural History to 597. Our earliest specimen dates back to 1872 (nearly 150 years ago!), and we have specimens representing every decade from 1890–1990, collected from 18 different states.
Prior to this roadkill, our last specimen was collected in 1991—so this is a good specimen to have considering the long time gap in our collection.
Researchers interested in studying long-term trends of rattlesnakes can search online databases such as VertNet to find which museums have specimens, and then examine specimens from several different museums to understand long-term changes in distribution, size, or breeding phenology, and how those may be associated with changes in land use due to increased human population sizes, or changes in climate. We’re sad to have found this beautiful specimen killed on the road, but I’m pleased to know that as part of our collection, it may provide a key element of understanding broader ecological patterns.
Jennifer A. Sheridan is the Assistant Curator in the Section of Herpetology at the Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.