Spatial and temporal variability in growth of giant gartersnakes: Plasticity, precipitation, and prey

Journal of Herpetology
By: , and 



The growth rate of reptiles is plastic and often varies among individuals, populations, and years in response to environmental conditions. For an imperiled species, the growth rate of individual animals is an important component of demographic models, and changes in individual growth rates might precede changes in abundance. We analyzed a long-term dataset on the growth of Giant Gartersnakes (Thamnophis gigas) to characterize spatial and temporal variability and evaluate potential environmental predictors of growth. We collected data on the growth in snout–vent length (SVL) of Giant Gartersnakes over 22 yr (1995–2016) from eight sites distributed throughout the Sacramento Valley of California, USA. The von Bertalanffy growth curves indicated male Giant Gartersnakes grew faster toward shorter, asymptotic SVL than did females. Nearly equal variability in growth was attributable to differences among years and among sites. From 2003–2016 we collected data on precipitation, temperature, and the abundance of fish and anuran prey at each site and used these variables as predictors in growth models of Giant Gartersnakes. Snake growth was positively related to the amount of precipitation that fell during the prior water year and the abundance of anurans at a site. Fish and frog abundance interacted to affect snake growth: at low abundances of one prey type, the other positively affected growth, but the slope of this relationship decreased as alternative prey abundance increased. Our results highlight the plasticity of growth in this threatened snake species, point to potential environmental drivers of growth, and provide valuable data for demographic modeling efforts.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Spatial and temporal variability in growth of giant gartersnakes: Plasticity, precipitation, and prey
Series title Journal of Herpetology
DOI 10.1670/17-055
Volume 52
Issue 1
Year Published 2018
Language English
Publisher Society for the Study of Amphibians and Reptiles
Contributing office(s) Western Ecological Research Center
Description 10 p.
First page 40
Last page 49
Country United States
State California
Other Geospatial Central Valley
Google Analytic Metrics Metrics page
Additional publication details