Date of Award:
Doctor of Philosophy (PhD)
David N. Koons
Free water can be a limiting factor to wildlife in arid regions of the world. In the western United States, management agencies have installed numerous, expensive wildlife water developments (e.g. catchments, guzzlers, wells) to: 1) increase the distribution or density of target species, 2) influence animal movements, and 3) mitigate for the loss of available free water. Despite over 50 years as an active management practice, water developments have become controversial for several species. We lack an integrated understanding of the ways free water influences animal populations. In particular, we have not meshed understanding of evolutionary adaptations that reduce the need for free water and behavioral constraints that may limit use of otherwise available free water with management practices. I propose a conceptual framework for understanding more generally how, when, and where wildlife water developments are likely to benefit wildlife species. I argue that the following five elements are fundamental to an integrated understanding: 1) consideration of the variable nature in time and space of available free water, 2) location and availability of pre-formed and/or metabolic water, 3) seasonal temperature and precipitation patterns that influence the physiological need for water, 4) behavioral constraints that limit use of otherwise available free water, and 5) proper spacing of water sources for target species. I developed this framework from work done primarily with chukars (Alectoris chukar). I also report supporting evidence from research with mule deer (Odocoileus hemionus). Chukars demonstrated a spatial response to available free water when estimates of dietary moisture content were < 40%. Mule deer photo counts were reduced at water sources with small-perimeter fencing, suggesting increased predation risk caused mule deer to behaviorally avoid use of otherwise available free water. When all five framework elements are considered, I found strong evidence that wildlife water developments have benefited some chukar populations. Historic chukar counts suggested a population benefit following installation of wildlife water developments. Experimental removal of access to free water caused increased movements and decreased survival of adult chukars.
Larsen, Randy T., "A Conceptual Framework for Understanding Effects of Wildlife Water Developments in the Western United States" (2008). All Graduate Theses and Dissertations. 189.
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