Historical Changes of Reptiles and Amphibians of Northwest Indiana Fish and Wildlife Properties

Article excerpt

ABSTRACT.-We conducted the first formal quantitative study of the herpetofauna of the Jasper-Pulaski, Willow Slough and LaSalle Fish and Wildlife areas (FWA) in northwest Indiana from 1994-1996 to gather baseline data necessary to determine distribution and status of species and to monitor long-term population trends. We compared our results with those of earlier collectors Chapman Grant, Paul Swanson and Sherman Minton. A total of 339 populations of 13 amphibian species and 78 populations of 22 reptile species were encountered from 1994-1996. Only 9 species were found at all three FWAs and only 11 were commonly encountered. Sixteen new site records and new county records were made while at least 7 species with validated records before 1972 were not found during this survey and may be locally extirpated. The relative abundance of species at Jasper-Pulaski FWA has changed between the 1930s and 1990s with declines of the thirteen most abundant species and increases in some formerly overlooked or rare species. Large-scale changes in habitat may be partly responsible for changes in species abundance. All of the state-listed species (Acris crepitans blanchardi, Rana blairi, R pipiens, Thamnophis p. proximus, Clemmys guttata, Emydoidea blandingii, Kinosternon s. subrubrum, Terrapene a. ornata, Opheodrys vernalis and Sistrurus c. catenatus), except Ambystoma laterale, have clearly declined.

INTRODUCTION

Change in amphibian and reptile biodiversity can result from anthropogenic habitat alteration (Hecnar and M'Closky, 1996) or natural ecological processes (Skelly et al., 1999). However, faunal surveys conducted before widespread habitat alteration that allow rigorous assessment of changes in amphibian and reptile populations are rare (Karns, 1988; Barinaga, 1990; Lannoo et al., 1994; Busby and Parmelee, 1996; Fisher and Shaffer, 1996). Such surveys are essential to the assessment of species losses or gains and to development of causal hypotheses. Several studies in the Midwest suggest that amphibian and reptile diversity declines can occur when habitat is lost, disturbed or fragmented (Lannoo et al., 1994), but can remain stable when native tracts of complex native vegetation and wetlands are preserved (Karns, 1988; Busby and Parmelee, 1996).

Formal study of the herpetofauna ofJasper-Pulaski (JP), Willow Slough (WS) and LaSalle (LS) Fish and Wildlife Areas (FWAs) in northwest Indiana began in the 1930s when Major Chapman Grant and Paul L. Swanson enlisted numerous people under their supervision to gather specimens of amphibians and reptiles. Their publications are based partially on observations and collections from JP (Grant, 1936; Swanson, 1939). In the early 1950s, Dr. Sherman Minton, Jr. conducted the only known herpetological study at WS (Minton, 1972; pers. comm.). These early surveys indicate that at least 16 amphibian and 26 reptile species historically inhabited these FWAs. The nearby LS was never formally surveyed for amphibians and reptiles, however a few records were made (Minton, 1972). The Indiana Depart ment of Conservation (IDC) at JP during 1931-1933 gathered the only quantitative data on the number of animals seen or captured. Grant (1936) reported these observations. However, they must be reviewed cautiously for potential errors because no vouchers were returned and Grant did not verify specimens. Grant (1936) and Swanson (1939) made qualitative statements (common, rarely encountered, etc.) on the relative abundance of species at JP and did retain vouchers.

In northwest Indiana along and south of the Kankakee River these three FWAs form the core of sizable natural areas. Together they contain remnants of wetland, oak forest, savanna and prairie elements in this unique region of Indiana (Lindsey et al., 1969). LaSalle (1480 ha), in northwest Newton County and southwest Lake County, contains a stretch of the Kankakee River and a small portion of the once expansive Grand Kankakee Marsh (Petty and Jackson, 1966). …