The Minnesota Biological Survey (MBS) conducts field surveys for amphibians and reptiles from April through September utilizing a variety of survey techniques.
The Blanding's turtle (Emydoidea blandingii) is a threatened species in Minnesota. It can be observed basking on beaver lodges or wetland edges in early spring. Photo by C. D. Hall.
Drift fences are used to capture salamanders. Photo by C. D. Hall.
Turtles are documented by scanning wetlands and riparian habitats for basking turtles, and by capturing turtles in hoop nets. Captured turtles are aged, sexed, and checked for reproductive condition prior to release. Searches are also conducted in open, sandy areas near wetlands in early June to locate nesting females or predated turtle nests.
Anuran call surveys document breeding frogs and toads by identifying the calls of males at night. At selected wetland locations all species heard calling during a 3-minute interval are recorded and a corresponding call intensity is estimated. This technique is used from April through July to obtain information during all species calling periods.
Drift fences capture secretive amphibians and reptiles and record seasonal movements from one area to another. A drift fence typically consists of a 50-foot length of aluminum flashing which creates a barrier, guiding animals into funnel or pit-fall traps. This technique is most effective during the spring when animals are dispersing from overwintering sites.
Terrestrial searches find amphibians and reptiles by turning over logs and rocks and searching an area in a systematic manner. Basking surfaces or rock crevices are also examined.
Road surveys find amphibians and reptiles during times, such as after a warm rain, when amphibians may be moving across roads.
Other observations, such as road-killed animals, tracks, and nests are recorded when encountered.