Abstract

Research that investigates the impact of invasive plants on reptiles, particularly snakes, is sparse. Butler's Gartersnake (Thamnophis butleri) is a rare snake, endemic to the upper midwestern United States. Little research has focused on the habitat selection of this snake, which is often sympatric with the Common Gartersnake (Thamnophis sirtalis). The highly invasive wetland grass Phalaris arundinacea(reed canarygrass [RCG]) has become established or dominant throughout much of the geographic distributions of these snakes. The impacts of this invasive grass on the habitat selection of T. butleri and T. sirtalishave not previously been examined. During 2 yr of drift fence surveys at three survey sites and five habitats sampled in southeastern Wisconsin, we captured 243 adult T. butleri and 311 adult T. sirtalis. Thamnophis sirtaliswas found more often in RCG than T. butleri, which appeared to have more specific habitat needs and most often occurred in upland habitats, particularly grassland, rather than wetlands. These findings have important regulatory and conservation implications for the globally rare T. butleri. For example, our data support the importance of upland habitat protection as part of conservation strategies for T. butleri. In addition, management of wetland habitat for this species must consider the impact of RCG and direct habitat restoration strategies accordingly.