Surveys for the Northern Ring-necked Snake (Diadophis punctatus edwardsii) in Northeastern Minnesota

Casper, Gary

The Northern Ring-necked Snake (Diadophis punctatus edwardsii)is a little known small reptile that reaches the northern limit of its range in northeastern Minnesota, where it has been recorded from only a few St. Louis and Lake county locations (Oldfield and Moriarty 1994; Carol Hall, personal communication 2012). It is a small, fairly secretive, animal with fossorial habits, and is often overlooked in biological surveys. In 2011, surveys performed for the Lake Superior Binational Program documented a few more records for this species in Lake County (G. Casper unpublished data). This study further evaluates known records in northeastern Minnesota, reports on surveys in May, June, July and September 2012, and discusses habitat features that may be important to the species. In sum, Northern Ring-necked Snakes are distributed from northern Carlton County (Jay Cooke State Park) to southwestern Cook County, with records hugging the north shore of Lake Superior, where climate moderation may explain the northern range limits. The maximum confirmed distance from the lake is approximately5 miles (specimen GSC 787).The distribution of populations in this region is probably more or less continuous, although there are gaps expected where habitat conditions are less suitable and in developed areas (i.e., greater Duluth). More southern outlying records in Pine County may be disjunct or not – more surveys are needed in this area to assess distribution extent. Additional gap surveys are also warranted in southeastern St. Louis County (between Duluth and the county Two Harbors), south-central Lake County (between Two Harbors and Gooseberry Falls State Park), southeastern Lake County (between Tettegouche State Park and the Cook County line), and in southwestern Cook County (to determine the northern range limit). The status of populations remains unknown. Northern Ring-necked Snakes were encountered much less frequently than the other two native snakes (Common Gartersnake, Northern Red-bellied Snake) on surveys in this area (G. Casper unpublished data). Whether this means they are less abundant, or simply less detectable due to differing or more secretive habits, is unknown. Several populations on public lands have been identified in this study which could be used to determine demographic parameters and conservation status through mark-recapture studies. Such studies are recommended in order to obtain baseline data for status assessment, and for monitoring the effects of ongoing climate change on the species.