Use of upland habitat by the Butler’s gartersnake (Thamnophis butleri).

Butler’s gartersnake, Thamnophis butleri, is a state-threatened species in Wisconsin. This
species occupies open-canopy habitat, including both wetlands and adjacent uplands, but
very little is known about the extent of use of upland habitats by the Butler’s gartersnake.
We studied how far T. butleri ranges into upland habitats adjacent to wetland hibernacula
in southeastern Wisconsin. We found that 25% of 329 observations of T. butleri were
within 63 ft (19 m) of a wetland edge; 50% within 138 ft (42 m), and 75% within 238 ft
(72 m). These observations provide an ecological basis for establishing protected buffer
zones around wetlands known to support T. butleri populations. Observations of the
common gartersnake, Thamnophis sirtalis, in the same habitat are compared with
observations of T. butleri.