Midget Faded Rattlesnake Monitoring in Wyoming

We began our second consecutive year of midget faded rattlesnake monitoring in Wyoming  during  the second week of May.  I’m joined initially by Denim Jochimsen and Josh Parker.  Josh, a faculty member at Clayton State University in Georgia, is a collaborator on our project and is able to participate for this week before he returns to Georgia to teach.  Denim, who is a Ph.D. student at the University of Idaho studying the community ecology of the reptiles in the area, will be working here most of the summer.  It has been a cold spring so far in Wyoming and we’re not sure how active the snakes will be.  Last year we found snakes as early as April, and many snakes had already left the dens by this time in May.  We’re hoping the cool weather means that snakes have been staying near the den and will be easier to find.  However, our arrival is greeted by more cold, overcast weather and from Sunday to Wednesday we only find 2 snakes. We found both within den entrances, so we expect to locate more once the weather improves.

On Thursday our luck turns as the weather improves, and we have sunny days in the 60s and 70s before rain returns on Saturday afternoon.  We are joined by three more people:  Andy Gygli, who is an undergraduate at University of Idaho who will be assisting Denim throughout the summer; Steve Mackessy, a professor at University of Northern Colorado, who will be visiting for a few days to collect venom for his research; and Kaye Holman, a Ph.D. student at Colorado State University, who assists Steve in the field and lab.  Steve is studying how snake venom can be used to develop cancer drugs, and the venom he collects this week will be used for that research.  We visit five den sites and the snakes are certainly taking advantage of the sunny weather – we locate 60 snakes in two and a half days!

The age and condition of the snakes we find mirror that of last year – the snakes appear to be doing well as the region comes out of drought.  Last year we found lots of pregnant females and this year a third of the snakes we have found so far are less than one year old.  Almost all of the large females are gravid this year, and we captured two gravid snakes that we estimate to be only 3 years old.  Furthermore, we recaptured two females from the previous year that were gravid in both years.  Previous research by Josh as part of his Ph.D. studies in 2001-2003 suggested that females gave birth, at most, every other year. That research took place during drought years, and so it seems that greater precipitation in recent years has improved the reproductive capability of rattlesnakes.  So far, both our field work and modeling efforts point to the importance of climate for these populations.  How climate change might impact the future of midget faded rattlesnakes is a natural follow-up question that we hope to address.

Despite our productive weekend, the bad weather has returned, and has temporarily halted our field efforts.  As I write this, the sun has been hidden by clouds for 3+ days. But this weekend promises better weather, and we’re looking forward to finding even more snakes at additional dens as we continue to learn more about this unique, secretive rattlesnake.

Photo credit:  Steve Spear