Population Patterns of Copperbelly Water Snakes (Nerodia Erythrogaster Neglecta) in a Riparian Corridor Impacted by Mining and Reclamation

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ABSTRACT.-

Habitat loss has been identified as a principle reason for decline of many water snakes, and surface mining for coal could potentially put Copperbelly Water Snakes (Nerodia erythrogaster neglecta) at risk due to the severity of land cover change that takes place once mining and reclamation are complete. We studied Copperbelly Water Snakes in riparian habitat impacted by adjacent surface mining in southern Indiana. Snakes were surveyed pre-mining (1992 and 1993), during mining (1994 to 1996) and post-mining (1997 to 2000). Abundance of Copperbelly Water Snakes (cws/km ± SE) was higher after mining (5.43 ± 0.37) compared to abundance levels before (2.04 ± 0.74) or during mining (3.32 ± 0.76). No Copperbelly Water Snake was observed in reclaimed habitat immediately following reclamation, but use of reclaimed habitat by these snakes was evident in subsequent years (n = 89). Size class distribution of Copperbelly Water Snakes observed in reclaimed habitat largely paralleled that of the entire population of these snakes in the flood plain. Evidence of reproduction by Copperbelly Water Snakes, in the form of juveniles (<76 cm in length) and young-of-year (<30 cm in length), was observed throughout the study. These data indicate that the population of Copperbelly Water Snakes was reproductively active, sustained higher levels of abundance following completion of mining and reclamation and made frequent use of reclaimed habitat. The extensive use of constructed ponds and drainage ditches by these snakes suggests that reclamation following mining can be done in a manner that facilitates recovery of habitat for this species.

INTRODUCTION

The Copperbelly Water Snake (Nerodia erythrogaster neglecta) is a subspecies of the Plainbelly Water Snake having a disjunct distribution of isolated and relatively isolated populations ranging from southern Michigan to portions of Indiana, southern Illinois, northwestern Ohio and northwestern Kentucky (Conant, 1934). The Copperbelly Water Snake is endangered in Indiana (Anonymous, 1970) and is classified as threatened by the U. S. Fish and Wildlife Service north of the 40th parallel (USFWS, 1997). The Copperbelly Water Snake is protected below this line by a conservation agreement developed in 1996 by state and federal agencies, conservation organizations and private industry (Garrison, 1996).

Six subspecies of the Plainbelly Water Snake occur, with the Copperbelly Water Snake and the Yellowbelly Water Snake (Nerodia erythrogaster flavigaster) listed by Dodd (1987) as snakes in need of conservation and management. The status of the Copperbelly Water Snake in both Ohio (Conant, 1934, 1955) and Michigan (USFWS, 1997) is precarious at best, with some isolated populations observed in Kentucky already considered extirpated (B. A. Kingsbury, Indiana-Purdue University, pers. comm.).

Data are lacking to evaluate the possible impact of surface mining and reclamation practices on populations and habitat of the Copperbelly Water Snake. Kingsbury and Coppola (2000) demonstrated the importance of assessing the location of hibernation sites to aid in future habitat restoration efforts of the Copperbelly Water Snake, and Roe et al. (2004) recommend more study to evaluate the factors that significantly impact the prey base of this species. Regardless, population responses associated with surface mining and reclamation in and around habitats suited to Copperbelly Water Snakes have not been measured. The success of conservation strategies for the Copperbelly Water Snake requires that monitoring approaches be devised that accurately assess the status of populations and existing habitat conditions, especially where potential land-use conflicts such as surface mining exist. Herein we present the findings of a 9-y study of the Copperbelly Water Snake in Pigeon Creek flood plain, southern Indiana. We tested two hypotheses with these data: that adjacent surface mining and associated habitat alteration might negatively affect the abundance of Copperbelly Water Snakes in the flood plain corridor and that habitat restoration efforts might be insufficient for supporting Copperbelly Water Snakes on reclaimed land. …