INTRODUCTION 



Increasing concern about declining amphibian populations and continued threats to their 

 wetland habitats has prompted many state and federal agencies to inventory local amphibian 

 species and revisit histoncal sites to document current status. The limited knowledge of 

 amphibian status and distribution in western Montana 50 years ago (eg Rodgers and Jellison 

 1942, Brunson and Demaree 195 1 ) has been supplemented by a recent series of survey etYorts 

 (e.g. Werner and Reichel 1994, Hendricks and Reichel 1996, Marnell 1997, Werner et al 1998), 

 a comprehensive summary is presented in Maxell (1999). 



The amphibian and wetland reptile survey of the Thompson Chain of Lakes in Sanders 

 County presented here contnbutes to a growing body of knowledge on the status and distribution 

 of amphibians and reptiles in northwest Montana. The 2000 inventory supplemented an 

 inventory of wetland vegetation in the same area. Both field inventories were supported by 

 funding from the Montana Department of Fish, Wildlife & Parks. 



METHODS 



Sites for amphibian surveys (see Fig. 1-4) were selected based on information received 

 during discussions with the Heritage Program wetland ecologist and MTFWP personnel, and 

 study of USGS 7.5' topographic maps (Thompson Lakes, Mont. 1983 photorevised. Loon Lake, 

 Mont. 1983 photorevised) The Thompson Chain of Lakes has not been the object of previous 

 systematic amphibian surveys, so a wide range of sites was selected Nevertheless, priority was 

 given to isolated wetland sites lacking introduced or native fish. Therefor, survey effort of the 

 major lakes was very limited. 



From 15-105 minutes were spent during each site survey (Table 1), depending upon the 

 size of the area, site conditions (including weather), and what was found Shorelines and 

 wetland margins were searched for adults and juveniles while walking slowly along the edge, 

 and sites were also scanned for turtles using an 8-power binocular The entire perimeter was 

 searched at smaller sites. The adjacent shallows were also inspected, all May surveys included 

 visual searches for egg masses attached to submerged and emergent vegetation At regular 

 intervals (where appropriate) the aquatic habitat was sampled for tadpoles or larvae using a 

 dipnet Time of day and duration of searches (a measure of search effort: Heyer et al. 1994, 

 Olson et al. 1997), weather, and species encountered were recorded on standardized U.S. Fish 

 and Wildlife Service data sheets Some sites were visited more than once to increase the 

 possibility of detection and document phenology of development 



RESULTS AND DISCUSSION 



Twenty-six site surveys were conducted at 16 sites during two visits (early May, early 

 June) to the Thompson Chain of Lakes. Four amphibian species (long-toed salamander 

 Ambysioma mucroJactylum. western toad Biifa horeas. Pacific tree frog Hyla re^illa, Columbia 

 spotted frog Rana luteiventn.s) and three reptile species (painted turtle ( 'hry.semy.s picia, common 

 garter snake Thamnophis sirtulis, western terrestrial garter snake ihunuiophis ele^^aiis) were 

 detected at 13 of the survey sites (Table 1). The most frequently detected species, long-toed 



