Introduction

The biodiversity of the South is impressive. Factors contributing to that diversity include regional gradients in climate, geologic and edaphic site conditions, topographic variation, natural disturbance processes, and the activities of Native Americans and European settlers (Boyce and Martin 1993, Delcourt and others 1993, Healy 1985). These factors have contributed to the diversity of several species groups: salamanders, snakes, and turtles (White and others 1998). The evolution of plants and animals, combined with the isolation that characterizes some habitats, produced remarkable levels of endemism—species that are restricted to special habitats.

The terrestrial vertebrate fauna of the South, including the entire States of Texas and Oklahoma, consists of 1,208 species. This total includes 170 amphibians, 197 reptiles, 595 birds, and 246 mammals (NatureServe 2000). Species richness is highest in Texas, Florida, North Carolina, and Georgia (fig. 5.1). North Carolina leads in amphibian diversity, while Texas leads in the richness of mammals, birds, and reptiles.

The variation in species richness among States is influenced by differences in size, geographic location, and environmental complexity (Stein and others 2000). Texas leads the region with 911 vertebrate species; diversity there is influenced by the State’s large size and its diversity of habitats (NatureServe 2000). Florida, North Carolina, and Georgia each support over 600 vertebrate species. The smallest number of species (487) occurs in Kentucky. Texas and Florida support species typical of Latin America and the Caribbean that reach their northern limits there (Stein and others 2000). For example, the northern limit for the American crocodile is in the Florida Keys and south Florida.

This diverse array of vertebrate species is found in a variety of habitats. A habitat is comprised of the physical and biological resources that allow a species to survive and reproduce. The habitat requirements for some species may be quite narrow, while those for another may be rather broad.

A species may require a certain habitat structure such as vegetation height, percent canopy cover, floristics, seral stage, patch size, or diversity and interspersion of plant communities. Some species are constrained by abiotic factors such as the precise cave temperatures required by many bat species. These features of habitat influence the distribution and abundance of species (Dickson 2001).

The habitat conditions for southern species have been modified by several factors (Buckner 1989). Habitat loss and degradation are serious threats to the region’s fauna (Noss and others 1995, Williams 1989). The rapid growth of the human population has resulted in land use conversion, urban sprawl, and habitat fragmentation (White and others 1998). Landscape modification has been accompanied by habitat isolation, water and air pollution, and altered disturbance regimes (Lorimer 2001, Trani and others 2001). In addition, southern wildlife has been influenced by the introduction of exotic species and the overexploitation of native species. Of particular concern is collection of species for the pet trade and overharvest of commercial species (Flather and others 1998). These factors have influenced species and their habitats in different ways.

This chapter provides an overview of the habitat associations of birds, mammals, reptiles, and amphibians in the South. The focus is on vertebrates because information on the regional biogeography of many terrestrial invertebrate groups is lacking (Echternacht and Harris 1993). Additional information on plant and animal associations is provided in chapter 1, chapter 2, and chapter 23.

Taxa groups are described, and general habitat associations for each are summarized. The status, distribution, and habitat requirements are provided for selected species of concern. Finally, conservation and management actions are suggested for enhancing habitat associations and mitigating known threats.

The following sections discuss the conditions needed to maintain and enhance conditions for species that occupy the terrestrial habitats of the South. Scientific names are provided in the chapter tables and the master species list in the Assessment appendix; therefore, only common names are provided in the text.