Through the Save The Snakes Pacific States Grant Program, Save The Snakes supports Emily Martin 2023 to increase awareness about snakes in Oregon, Nevada, and California. Her project aims to understand how rattlesnakes respond to ongoing climate change, habitat fragmentation and urbanization.
Project Title:
Geographic Variation in Clutch Size of Northern Pacific Rattlesnakes
Project Summary:
For many terrestrial vertebrates including birds and some reptiles, clutch size tends to be positively correlated with latitude, irrespective of maternal body size. The underlying mechanism for this trend—known as the latitudinal clutch size gradient—remains largely unknown. Decades of avian research have generated three main hypotheses, which implicate per-capita food availability, day length, or nest predation as the primary drivers of this trend across taxa. Unfortunately, the highly mobile, often migratory nature of birds has impaired any attempt to draw causative conclusions.
Aims and Objectives:
In early spring, when rattlesnakes are emerging from hibernation, we plan to attend known hibernacula. These den complexes are located in areas where reproductive data for C. oreganus has not yet been collected, which maximizes the scientific impact of the data collected at each site. At each complex, we will conduct visual surveys to identify basking and exit locations, which will ensure that we limit the effect of capture disturbance to snake-dense areas. I will capture snakes either via snake tongs and hook or by constructing temporary drift fences at emergence points. At sites where drift fencing is appropriate, drift fences will be constructed using a box trap array with four pitfall or funnel traps at the end of each.
Male and juvenile rattlesnakes will be released immediately upon capture. Adult females will be scanned for PIT tags (or visually inspected for non-toxic acrylic paint markings). Females who have already been captured that year will be immediately released at their capture location.\ Snakes will be placed head-first into a clear plastic restraint tube to minimize the risk of accidental envenomation. Morphometric measurements will be taken (SVL and weight), and gravid females will be palpated for the presence of enlarged ovarian follicles. Any enlarged follicles will be counted according to Taylor and Booth, 2016. Following aseptic procedure, a PIT tag will be injected subcutaneously, anterior to the cloaca, or non-toxic acrylic paint will be used to mark the rattle in a unique identification sequence. Each snake will then be released at its precise capture location.
Goal:
This project uses phylogenetic comparative methods to test explicit predictions of the three established hypotheses in a novel study system: Squamate reptiles. To complement this comparative approach and determine the role of intra-specific reproductive plasticity on the latitudinal clutch size variation in snakes, we have also chosen to collect reproductive data on several known populations of Crotalus oreganus. These data will give us a comprehensive look at how and why reproductive output in this species varies geographically and will help us understand how these animals may respond to ongoing climate change, habitat fragmentation, and urbanization.
Support Snake Conservation
Emily Martin’s project is a recipient of the 2023 Save The Snakes Pacific States Grant Program. These grants are made possible because of the generosity of compassionate people and organizations who are inspired and dedicated to protect threatened snake populations and mitigate human-snake conflict around the world. Please donate today to help us continue to fund projects like their snake conservation project in the United States. Thank you for your support.
