Population ecology of narrow-headed gartersnakes
July 2021 - May 2025
- U.S. Fish and Wildlife Service
The narrow-headed gartersnake (Thamnophis rufipunctatus, hereafter THRU) is a federally threatened species endemic to the Mogollon Rim of central Arizona and western New Mexico. This species has undergone marked declines throughout its range due primarily to introduced fish and crayfish and loss or degradation of riparian and within-stream habitat. There is currently no THRU species recovery plan and in 2020 the U.S. Fish and Wildlife Service formally began the most recent Species Status Assessment (SSA) for THRU, which is anticipated to form the basis for the species recovery plan. However, there is relatively little empirical data available on the movement ecology and population dynamics of THRU, which span multiple seasons. This lack of critical information on how snakes seasonally shift activity and habitat use is currently an impediment to conservation managers to more accurately assessing range-wide and site-specific population risk and implement management actions. Additionally, a lack of empirical demographic parameter estimates (e.g., survival) inhibits efforts to conduct population viability analyses. This information would allow managers to identify at-risk populations and direct site-specific management actions, thereby aiding in species recovery.
This proposed study will address ecological and geographic gaps in the knowledge of THRU by studying the spatial, habitat, and population ecology of THRU along the Tularosa River, New Mexico. The results of this proposed study, when combined with previous studies on THRU, will help us better understand the geographic variation in THRU ecology and increase confidence in management recommendations and status assessments.
The goals of this study are to: (1) conduct two active seasons of intensive field sampling at one or more populations of THRU, including the Tularosa River in New Mexico; (2) use new and existing mark-recapture data to estimate survival and abundance; and (3) develop implantation and field tracking protocols using harmonic transponder tags using a closely related species, the western terrestrial gartersnake, and, conditional upon success of these efforts, implant harmonic transponder tags into juvenile and adult THRU in the Tularosa River to monitor space use and habitat selection.