Sensitive Herpetofauna of the Black Hills National Forest

Sensitive Herpetofauna of the Black Hills National Forest 

by Nate Stephens and Brian Smith

The Black Hills is home to 23 species of reptiles and amphibians, several of which are rare. The United States Forest Service considers four species of particular concern and classifies them as sensitive species on the Black Hills National Forest. Black Hills State University, in cooperation with the Black Hills National Forest, has been working for the past several years with the U. S. Forest Service to design management strategies to conserve these species. In this presentation we describe these species and threats to their populations.

The tiger salamander has one of the largest ranges of any amphibian in the world. In parts of its range it is threatened with extinction, but in many areas its population status is simply unknown. Its aquatic larval stage has been fairly well studied, but despite the large numbers of studies we still know little about the basic biology of this salamander and especially about the terrestrial stage of its existence.

The tiger salamander is even less well known in the Black Hills. We have found adults throughout the Black hills but at unpredictable times in unpredictable locations. Breeding ponds are very poorly known. Because terrestrial adults spend most of their time underground we have almost no knowledge of their habits. Sexually mature larval forms are also found in the Black Hills in various permanent springs and ponds. However, we know little about where they are found as well.

Like all amphibians the tiger salamander can be affected by diseases, pollution, acidification, over development, and over collection. However, our most important recommendation as regards the tiger salamander is simple survey work. We need to survey ponds throughout the Black Hills searching for this species at appropriate times of the year to determine the abundance and distribution of the tiger salamander in the Black Hills.

The northern leopard frog is threatened with extinction or is extinct across large parts of its wide historical range. Once one of the most widely distributed frogs in North America, its range has been shrinking for decades. A variety of reasons have been given for the extirpation of the northern leopard frog across its range, including over development, diseases, over collection, pollution, loss of the ozone layer, acidification, and other causes. Recently, deformed northern leopard frogs have been found across various parts of the upper Midwest of the United States. These deformations are currently unexplained.

We believe that northern leopard frog populations may still be secure in the Black Hills, but are worried that these populations could also disappear. We also know very little about the population status and abundance of this species in the Black Hills. We have recommended immediate surveys to determine population sizes in the Black Hills. We have also recommended that steps be taken to secure the small wetlands in which this species breeds and to protect riparian corridors along which northern leopard frogs move when traveling from pond to pond.

The redbelly snake, Storeria occipitomaculata, is a species of eastern North America. It is a small snake that feeds on soft-bodied invertebrates, such as slugs, that it finds in moist areas under cover items such as rocks, logs, and decaying plant litter. The life history of redbelly snakes is geographically variable, so studies in other regions may not help us to understand the life history of populations in the Black Hills, where they have not been studied. The species is divided into three subspecies, two of which are found exclusively in the eastern United States. The third is found in the west and was thought by taxonomists to be confined to the Black Hills. A recent specimen found near Bison, however, shows that redbelly snakes may be more widely distributed in South Dakota than previously thought.

The Black Hills redbelly snake, Storeria occipitomaculata pahasapae, was described in 1963 from the Black Hills. However other studies have found them in Minnesota, North Dakota, Nebraska, and Manitoba. Within the Black Hills, the snake is thought to inhabit most habitats that are threatened by encroaching ponderosa pine forest. The snakes may be threatened by loss of habitat, as wetlands are disappearing in the Black Hills. This may affect their prey, possibly slugs, which are very susceptible to desiccation. Management for the Black Hills redbelly snake would mean the preservation of these habitats and returning the historical diversity of habitats that occurred throughout the Black Hills.

The milk snake, Lampropeltis triangulum, is a diverse species with possibly the widest range of any American snake. This species is divided into 25 subspecies that vary in color, pattern, and general biology. Throughout parts of their range they are effective mimics of the dangerous coral snake. Because of their bright colors and harmless nature they are often kept as pets. The northernmost and probably least know subspecies is the pale milk snake, Lampropeltis triangulum multisriata.

The pale milk snake is found throughout the Black Hills in Wyoming and South Dakota. This rare predator is thought to feed mainly on reptiles and small mammals. Although it is not dangerous to humans, it is often mistaken as the venomous coral snake and killed on sight. Coral snakes are not found within the range of the pale milk snake and there is no danger from them in South Dakota. The pale milk snake spends most of its time hiding and is therefore difficult to find, let alone study. Finding a pale milk snake in the Black Hills is rare and care should be taken not to disturb its habitat, as we know very little about them in the area. The management of this snake is concerned with habitat diversity, which has been shown to increase the abundance of prey items the snake may use.  

There are several constant themes running though each of these accounts. Probably most importantly the Black Hills area has long been neglected by herpetologists. It is one of the last parts of the United States to still lack basic survey work on reptiles and amphibians. We suspect that several management actions, including cattle grazing, logging, development, and mining, can have adverse affects on these species. However, before designing wise management strategies that accommodate the interests of the wide variety of users of the Black Hills National Forest, we have recommended a program of extensive surveys to determine the status and abundance of these species.