Terrestrial Gartersnake (Thamnophis elegans) consuming a Western Meadow Vole (Microtus drummondii) in the Sangre de Cristo Mountains of New Mexico

The Terrestrial Gartersnake (Thamnophis elegans) is a dietary generalist occurring in the western half of the United States, southwestern Canada, and northern Mexico. Terrestrial Gartersnakes are known to consume a variety of small mammals, including voles (Microtus). Herein we report on an observation of the Terrestrial Gartersnake consuming a Western Meadow Vole (Microtus drummondii). On 27 June 2025, we captured a large adult Terrestrial Gartersnake underneath a log just upstream of a North American Beaver (Castor canadensis) dam on the Vermejo River, Colfax County, New Mexico that regurgitated a partially digested adult Western Meadow Vole. Trapping in the immediate vicinity earlier that morning and elsewhere in the same watershed indicated high populations of Western Meadow Voles. Our observation of a large adult Terrestrial Gartersnake consuming an adult Western Meadow Vole likely reflects an ontogenetic diet shift toward mammals, particularly voles, observed in other studies for adult snakes of this species.