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A Conceptual Framework for Understanding Effects of Wildlife Water Developments in the Western United StatesLarsen, Randy T 01 December 2008 (has links)
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.
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Ecological Investigations of Chukars in Western UtahLarsen, Randy T. 11 July 2006 (has links) (PDF)
This thesis presents three separate manuscripts in chapter format dealing with the ecology of Chukars (Alectoris chukar) in western North America. All three manuscripts have been formatted for publication in professional journals. Chapter one confirms discovery of ingested lead pellets in Chukars across a broad region of western Utah including all four western counties sampled. Prevalence rates were 1.9% (n=105) for crops and 10.7% (n=75) of gizzards showing no evidence of penetration wounds. Ingestion is likely related to grit size preferences that are consistent with common shot sizes. The second chapter describes watering patterns and water-site selection of Chukars. Chukars watered during daylight hours with a modal hour from 1100 hours to 1200hours. Annual patterns suggest no use of water sources from November to May with first visits occurring in June of each year and last visits in October. Shrub canopy cover was the only variable to discriminate between use and non-use watering sources (P < 0.01). Cross validation showed a predictive success rate of 84%. Significant differences were found between use and non-use sites in terms of protective cover (P < 0.01), but not total cover (P > 0.05). Chukars were found to have a shrub canopy threshold near 11%; water sources meeting this threshold received use, whereas those not meeting this threshold did not. Chapter three challenges several claims postulating negative conservation implications relative to exotic Chukars in North America. These claims were proven to be unfounded with no evidence of cheatgrass (Bromus tectorum) dispersal despite widespread utilization. Furthermore, guzzlers designed to benefit Chukar populations were heavily utilized by native species and only slightly (two species at three sites) by other exotics. These three manuscripts illuminate several areas of Chukar ecology and represent a significant advancement in our understanding of this bird and its management.
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Causes, Extent, and Consequences of Lead-Pellet Ingestion by Chukars (Alectoris Chukar) in Western Utah: Examining Habitat, Search Images, and ToxicologyBingham, R. Justin 01 May 2011 (has links)
Lead ingestion adversely affects humans and over 130 species of wildlife. Wild chukars (Alectoris chukar) are documented to ingest lead, but the causes and consequences of this ingestion are poorly understood. The objectives of this research were to 1) examine the influence of habitat use, the hunting season, and seasonal climate on the extent and severity of lead ingestion by chukars in western Utah, 2) assess the effects of habitat use, feeding behaviors, and lead density on the causes of lead-pellet ingestion in captive and wild chukars, and 3) investigate the consequences of lead-pellet ingestion in captive chukars as a function of lead weathering, diet, and wild onion (Allium spp.) supplementation. I documented that 11.5% (n=54) of my sample of wild-harvested chukars contained an ingested lead pellet or increased liver lead (≥ 0.5 ppm). In conjunction with data from captive chukars dosed with lead, I was able to differentiate between bone-lead concentrations resulting from chronic or acute exposure to lead. I documented individuals from seven different mountain ranges with an ingested lead pellet or increased liver lead. I recorded 19 instances of ingested lead during June-October (n=221) and 20 during November-January (n=193). I observed 14 events of increased liver lead for June-October (n=97), but did not find a single occurrence during November-January (n=24). The frequency of lead-pellet ingestion by captive chukars increased significantly when given a greater density of lead pellets with food and when fed a diet with seeds and grit pebbles that were similar visually to lead pellets. I estimated a density of 1,712,134 pellets/Ha in soils at an area used for target shooting. I found significantly more lead pellets in soils near springs than near guzzlers or reference points. I calculated that as many as 58,600 pellets/Ha may be present in soils near springs, and up to 2,445 pellets/Ha in soils surrounding guzzlers and reference points. One #6 lead pellet was able to induce morbidity and mortality in captive chukars. A mixed-seed diet and lead weathering exacerbated the effects of lead ingestion, whereas wild onion supplementation alleviated them.
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