The Midden: Monitoring Habitat Use by Rattlesnakes
This article is the first in a series of posts showcasing articles published in the Winter 2023 issue of “The Midden”, Great Basin National Park’s semiannual resource management newsletter. The series will introduce you to some of the issues, projects, and management strategies currently happening in Great Basin National Park.
Where do rattlesnakes go in the summer in Great Basin National Park? How far do they travel? What do they eat? Learn how researchers from the University of Nevada-Reno are addressing these questions in a new research study.
Monitoring Habitat Use by Rattlesnakes
By Colton Irons and Kevin Shoemaker, Researchers, University of Nevada-Reno and Bryan Hamilton, Wildlife Biologist, National Park Service
In the summer of 2023, we set out to Great Basin National Park from Reno, Nevada to monitor Great Basin rattlesnakes (Crotalus lutosus) and the community of small mammals that serve as prey for this magnificent creature. We are tracking where the snakes go during the summer when they are most active and determining how far they travel from their hibernacula (also referred to as dens) in that given season.
With prescribed burns planned for our study region in November 2023, we will look for any changes in habitat use by rattlesnakes and their prey. The summer of 2023 (prior to prescribed fire treatments) gave us valuable baseline information, and after next year in 2024, we will find out how both populations were affected by the burns.
We captured approximately 50 rattlesnakes from April-October and a total of 156 small mammals during the month of July. Out of those 50 rattlesnakes, we selected 19 (11 males and 8 females) to track their movement patterns using radio telemetry in the Baker Creek Watershed. We first had to anesthetize the snakes to surgically implant them with radio transmitters.
Radios allowed us to track their movements in the wild, which we did weekly. The most adventurous snake we had traveled a total of 4.14 miles to and from their hibernaculum starting at 7,311 ft. and ending at 9,314 ft. All the snakes captured over the summer were examined for whether they were male or female, weight, length, and if they were captured previously by scanning for a PIT tag (a microchip that your cat or dog might have). We also collected blood and scale clip samples for genetics.
For the small mammal surveys, we set up live traps in the Baker Creek Watershed within the areas where the controlled burns would occur and at the Lehman Creek Watershed where burns wouldn’t occur. This will allow us to see how small mammal populations are impacted by areas treated and untreated by fire. For all small mammals we captured, we recorded sex, weight, and age, and we attached an ear-tag with a specific number (like an earring) so that if we caught that individual again, we would know. In 2023 we captured chipmunks (Tamias sp.), voles (Microtus sp.), shrews (Sorex sp.), and a whole lot of deer mice (Peromyscus maniculatus).
The summer of 2023 provided us with a lot of opportunities to present our findings at campgrounds to discuss fire ecology and the importance of rattlesnakes within the ecosystem, in terms of controlling the spread of disease in some small mammal populations. We also made very interesting discoveries in rattlesnakes feeding, mating, and socializing.
Stay tuned! In 2024, we plan to give more insight to folks on the predator-prey relationship between rattlesnakes and small mammals and how the prescribed burns affected this predator-prey interaction.
Photo: UNR researcher wrangling a rattlesnake. Colton Irons