This report, "Assessment of Grassland Ecosystem Conditions in the Southwestern United States: Wildlife and Fish," is volume 2 of a two-volume ecological assessment of grassland ecosystems in the Southwestern United States, and it is part of a series of planned publications addressing major ecosystems of the Southwest. Volume 1, An Assessment of Grassland Ecosystem Conditions in the Southwest (Finch, editor, 2004), focused on the ecology, types, conditions, and management practices of Southwestern grasslands. The second volume (herein) describes wildlife and fish species, their habitat requirements, and species-specific management concerns, in Southwestern grasslands. The first Southwestern ecological assessment, General Technical Report RM-GTR-295, emphasized forested ecosystems and was titled, An Assessment of Forest Ecosystem Health in the Southwest (by Dahms and Geils, editors, 1997). Given the complexities of grassland ecology and the increasing number of challenges facing grassland managers, the USDA Forest Service Southwestern Region, in partnership with the agency's Rocky Mountain Research Station, focused on grasslands in its second assessment. The assessment is regional in scale and pertains primarily to lands administered by the Southwestern Region (Arizona, New Mexico, Texas, and Oklahoma) of the U.S. Department of Agriculture, Forest Service. Broad-scale assessments are syntheses of current scientific knowledge, including a description of uncertainties and assumptions, to provide a characterization and comprehensive description of ecological, social, and economic components within an assessment area (USDA Forest Service 1999b). A primary purpose of volume 2 of the grassland assessment is to provide information to employees of the National Forest System for managing habitats and lands for wildlife and fish populations, both at the Forest Plan level for Plan amendments and revisions, and at the project level to place site-specific activities within the larger framework. This volume should also be useful to State, municipal, other Federal agencies, and to private landowners that manage or regulate wildlife and fish populations and their habitats in the Southwestern United States. The assessment is not a decision document because it identifies issues and risks to grassland ecosystems that provide the foundation for future changes to Forest Plans or project activities, but it does not make any site-specific decisions or recommendations.

Sustained conservation of species requires integration of future climate change effects, but few tools exist to assist managers. The System for Assessing Vulnerability of Species (SAVS) identifies the relative vulnerability or resilience of vertebrate species to climate change. Designed for managers, the SAVS is an easily applied tool that uses a questionnaire of 22 predictive criteria to create vulnerability scores. The user scores species' attributes relating to potential vulnerability or resilience associated with projections for their region. Six scores are produced: an overall score denoting level of vulnerability or resilience, four categorical scores (habitat, physiology, phenology, and biotic interactions) indicating source of vulnerability, and an uncertainty score, which reflects user confidence in the predicted response. The SAVS provides a framework for integrating new information into the climate change assessment process.

Experimental research and species distribution modeling predict that large changes in the distributions of species and vegetation types will occur due to climate change. Species responses will depend not only on their physiological tolerances but also on their phenology, establishment properties, biotic interactions (Brown and others 1997), and ability to evolve and migrate (Davis and Shaw 2001). The capacity of species and, thus, their distributions to respond to a warming environment also will be affected by changing disturbance regimes and other global change factors (Turner 2010). Because individual species respond to climate variation and change independently and differently, plant assemblages with no modern analogs can be expected (Williams and Jackson 2007). New plant assemblages might also arise in areas where novel climatic conditions develop (Williams and Jackson 2007). Support for predictions of novel climate regimes and corresponding plant assemblages is found in studies examining relationships among paleo-climate and plant community reconstructions. As Williams and Jackson (2007) pointed out: (1) many past ecological communities are compositionally unlike modern communities; (2) the formation and dissolution of past "no-analog" communities appear to be climatically driven and linked to climates without modern analogs; (3) many future climate regimes will probably lack modern analogs; and (4) novel communities and surprises should be expected in the future. Novel climate conditions coupled with vegetation communities that lack modern analogs pose significant challenges for resource managers. Accurate predictions of how species distributions will change under future warming are essential for developing effective strategies for maintaining and restoring sustainable ecosystems (Harris and others 2006). Several factors make predicting how species distributions and vegetation communities will change difficult. Global Circulation Models (GCMs) exhibit significant variation in forecasts of future temperature and especially precipitation (Christensen and others 2007). This variation is often amplified for topographically variable areas such as the Interior West (Rehfeldt 2006; Saenz-Romero and others 2010). In addition, information on species' relationships to climate variables is often lacking and must be inferred from data on current species distributions. And other factors such as competitive interactions with other species and disturbance regimes often obfuscate interpretation of species climate profiles in projected future climate space. In grassland, shrubland, and desert ecosystems, our understanding of likely changes in climate is limited. Also, we lack information on the climate profiles of the vast majority of species. Here, we provide (1) current forecasts for changes in climate over the remainder of the century and (2) available predictions for changes in regional vegetation types and individual species distributions. We then discuss the types of approaches that can be used to increase our predictive capacity and the research needs for these ecosystems.

The apparent decline in numbers among many species of migratory songbirds is a timely subject in conservation biology, particularly for ornithologists, ecologists, and wildlife managers. This book is an attempt to discuss the problem in full scope. It presents an ambitious, comprehensive assessment of the current status of neotropical migratory birds in the U.S., and the methods and strategies used to conserve migrant populations. Each chapter is an essay reviewing and assessing the trend from a different viewpoint, all written by leaders in the fields of ornithology, conservation, and population biology.