Water is essential to life. Three general forms of water exist: pre-formed water that is available in food, metabolic water that is created as a byproduct of life processes (e.g., metabolism of fat or breakdown of carbohydrates), and free water (i.e., water available for drinking). As humans settle arid environments, the addition of man-made free water sources (e.g., sewage ponds, catchment ponds) often occurs. In addition, a tool commonly used to increase the abundance or distribution of wildlife species in desert environments is the addition of water sources, usually specifically designed to benefit game species like bighorn sheep (Ovis canadensis), mule deer (Odocoileus hemionus), and chukar partridge (Alectoris chukar). In recent decades, some scientists have argued that adding water sources to deserts may have little to no effect on desert species because they are adapted to living in desert conditions, and have thus evolved to obtain their water needs in preformed and/or metabolic form. Scientists have also suggested that adding water sources to desert environments may actually harm some individual species and alter the arraignments of groups of similarly related species, known as communities. I conducted four studies at the U.S. Army Dugway Proving Ground to determine if man-made water sources have an influence on the rodent community, jackrabbits, and the canid community at the U.S. Army Dugway Proving Ground, Utah. I found that turning off water sources had no effect on abundance of rodent communities or jackrabbits. I found that a portion of coyotes used water sources and coyotes were only slightly less common near water sources once they were turned off. In addition, a portion of coyotes rarely or never drink from water sources and that coyotes did not leave their territories if water sources accessible to them were turned off. My final study revealed that turning off water sources did not influence kit fox survival or abundance, and that kit fox territories differed from areas associated with water sources in several key environmental characterizes, which may suggest that areas associated with water sources were not historically used by kit foxes. In summary, these findings suggest that water developments have little impact on the species that I studied.

Records of change of [delta]13C values in vertebrate teeth offer an opportunity to gain insight into changes in past vegetation. Increasingly, teeth from small mammals are used for such purposes, but because their teeth grow very rapidly, seasonal changes in vegetation potentially provide a large source of variability in carbon isotope composition, complicating interpretations of small mammal tooth isotope data. To investigate the controls of seasonality on the stable isotope composition of fossil teeth, we constructed a Monte-Carlo-based model to simulate the effects of changes in the seasonal pattern of diet in leporid lagomorphs (rabbits and hares) on the distribution of [delta]¹³C values in random populations of leporid teeth from the Edwards Plateau in central Texas. Changes in mean-state, seasonal vegetation range, and relative season length manifest themselves in predictable ways in the median, standard deviation, and skewness of simulated tooth [delta]¹³C populations, provided sufficient numbers of teeth are analyzed. This Monte Carlo model was applied to the interpretation of a 20,000 year record of leporid tooth [delta]¹³C values from Hall's Cave on the Edwards Plateau in central Texas. Variations in the [delta]¹³C values of teeth deposited at the same time (standard deviation = 1.69%) are larger than changes in the mean vegetation composition reconstructed from bulk organic carbon [delta]¹³C, indicating the influence of short-term variability, making it difficult to assess changes in mean C3/C4 vegetation from the tooth [delta]¹³C data. However, populations of teeth from different climate intervals (e.g., the late Glacial, Younger Dryas, and the Holocene) display changes in the shape of the tooth [delta]¹³C distributions. Interpretation of these changes as shifts in seasonal vegetation patterns that are based upon results from our model are consistent with hypothesized climatic changes. An increase in the standard deviation of the tooth population between the late Glacial and the Younger Dryas -- Holocene is consistent with an increase in seasonality. Furthermore, a shift to more C3-dominated vegetation in the tooth [delta]¹³C distribution during the Younger Dryas is accompanied by a more skewed population -- indicative of not only wetter conditions but an increase in the duration in the C3 growing season. However, late Holocene changes in vegetation are not clear in the tooth data, despite the evidence from bulk organic carbon [delta]¹³C values for an increase in % C3 vegetation of 57%. Small mammal teeth can potentially provide unique insights into climate and vegetation on seasonal and longer timescales that complement other data, but should be interpreted with a careful consideration of local conditions, taxon ecology and physiology, and the dominant timescales of isotope variability. / text