| Chapter 3—Threats to and Status of Resources27 |
strained by the applicable provisions of State water law. Water can be appropriated and applied only to a beneficial use recognized by the State of Wyoming, and though a considerable number of water rights have been approved by the Wyoming State Engineers Office, there is no formal list of approved or defined beneficial uses in Wyoming (Wyoming Joint Venture Steering Committee 2010). Without formal recognition of wildlife habitat creation, maintenance, enhancement, or management as a beneficial use in the State of Wyoming, the rulings for water appropriation can be inconsistent and can lead to wetland habitat loss that would directly affect wetland-dependent wildlife populations. As fragmentation increases, remaining habitats become geographically isolated and wildlife populations with limited dispersal abilities may potentially become genetically and spatially isolated.
Climate Change
Climate change has become one of the paramount conservation issues and management challenges. The term “climate” refers to the mean and variability of different types of weather conditions over time, with 30 years being a typical period for such measurements, although shorter or longer periods also may be used (Parry et al. 2007). The term “climate change” refers to a change in the mean or variability of one or more measures of climate (such as temperature or precipitation) that persists for an extended period, typically decades or longer, whether the change is because of natural variability, human activity, or both (Parry et al. 2007). Various types of climate change can have direct or indirect effects on species. These effects may be positive, neutral, or negative, and may change over time, resulting in different effects on species and associated habitats (Parry et al. 2007).
Mountain ecosystems in the western United States are expected to be especially sensitive to climate change. Data shows that many places in the Rocky Mountains have experienced three times the global average temperature increase over the past century. The magnitude of warming in the northern Rocky Mountains has been particularly significant, as shown by an 8-day advance in the appearance of spring phenological indicators since the 1930s (Cayan et al. 2001). The hydrologic regime in the northern Rockies has also changed in response to the shift in global climate, and is projected to experience further changes (Bartlein et al. 1997, Cayan et al. 2001, Stewart et al. 2004). Under global climate change scenarios, the mountainous areas of northwest Wyoming may eventually experience milder, warmer, wetter winters and drier summers (Bartlein et al. 1997). Furthermore, the pattern of snowmelt runoff may change, with a reduction in spring snowmelt (Cayan et al. 2001) and an earlier peak runoff (Stewart et al. 2004), resulting in relatively lower annual discharge during spring and summer.
There is no available information on the potential threats of climate change on the Wyoming toad, and there is no evidence of direct effects to the species at this time (USFWS 2013). Many species that are already listed as endangered or threatened may be particularly vulnerable to changes in climate; it is also recognized that, for some listed species, the likely effects may be positive or neutral. However, some studies have predicted that amphibians will be even more susceptible to climate change than bird or mammal populations because of their physiology; dependence on microhabitats and predictable hydrological regimes; limited dispersal abilities (Blaustein et al. 1994); and susceptibility to diseases that may be intensified by climate change (Pounds et al. 2006). Some models predict substantially larger changes in amphibian populations than in birds or mammals, based primarily on potential future range contractions and expansions. This multitude of projected impacts could exacerbate the current population declines of many amphibian species (Stuart et al. 2004). Many wetland and riparian habitats, such as those found within the boundary of the conservation area, are dependent on snowmelt from surrounding high-mountain ecosystems and are therefore expected to be more acutely affected by changes in runoff amount, timing, and quality than other habitats (Parry et al. 2007). Because the snowpack in high-elevation montane ecosystems directly affects the phenology of lower elevation watersheds, species associated with these systems may be more acutely affected than species in more temperate ecotypes.
For amphibians and reptiles, the timing of key ecological events is influenced by environmental conditions such as air and water temperatures and precipitation patterns. The timing of breeding, egg laying, metamorphosis, dispersal, and migration may shift in response to higher temperatures and changes in rainfall (Beebee 1995). As temperatures warm and the water in aquatic habitats becomes more variable, amphibians are likely to experience lower rates of survival to metamorphosis. Temperatures outside of their thermal optima can also cause physiological stresses (Gibbons et al. 2000). Because of their affinities to aquatic habitats and their small size, amphibians typically have relatively small home ranges and low dispersal rates (Duellman and Trueb 1994, Wells 2007), making them more vulnerable to changes in their environment. The Wyoming toad, in particular, is a glacial relict that is adapted to a cool montane climate with a reliably high spring runoff. As climate
