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Item Breeding ecology of greater sage-grouse in southwestern Montana(Montana State University - Bozeman, College of Agriculture, 2021) Cutting, Kyle Anthony; Chairperson, Graduate Committee: Jay J. Rotella and Bok Sowell (co-chair); Jay J. Rotella, Sean R. Schroff, Michael R. Frisina, James A. Waxe, Erika Nunlist and Bok F. Sowell were co-authors of the article, 'Maladaptive nest-site selection by a sagebrush dependent species in a grazing-modified landscape' in the journal 'Journal of environmental management' which is contained within this dissertation.; Jay J. Rotella, Emma Grusing, James A. Waxe, Erika Nunlist and Bok F. Sowell were co-authors of the article, 'Nutrient sources for offspring formation: diet-mother and mother-offspring isotopic discrimination in domesticated gallinaceous birds' submitted to the journal 'Isotopes in environmental and health studies' which is contained within this dissertation.; Jay J. Rotella, James A. Waxe, Aaron O' Harra, Sean R. Schroff, Lorelle Berkeley, Mark Szczypinski, Andrea R. Litt, Bok F. Sowell were co-authors of the article, 'Resource allocation effects on the timing of reproduction in an avian habitat specialist' in the journal 'Ecosphere' which is contained within this dissertation.The greater sage-grouse (Centrocercus urophasianus; hereafter: sage-grouse) is an umbrella species that needs large intact tracts of sagebrush habitat with habitat requirements that represent the needs of many other species found in the sagebrush biome of the American West. Much of the information collected to date on sage-grouse is from low-elevation, homogenous, landscapes, leaving information gaps for topographically complex, high elevation locations within the sage-grouse range. In this dissertation, I assess the following aspects of the breeding ecology of sage-grouse: 1) how females select nest and brood sites based on sagebrush type, along with livestock grazing features and other biotic and abiotic characteristics; 2) the influence of female nest-site selection on nest-survival outcomes; 3) experimentally derived isotopic discrimination values in domesticated gallinaceous birds as an estimation method for nutrient allocation strategies in wild sage-grouse; and 4) the degree to which females allocated nutrients from winter habitats for formation of offspring by comparing females nesting in southwest vs. central Montana. Based on the research, I found evidence that: 1) sage-grouse avoid a high-elevation sagebrush type that is the most common type in my study region and instead select for intermediate- or low-elevation sagebrush types for both nesting and brood rearing, 2) sage-grouse broods selected sites away from low-lying mesic areas and near ridgelines on upper slopes with south-facing aspects and sites further from cattle paths, 3) nest survival was (a) higher for nests placed away from fence lines, (b) lower in areas with more cow pies and taller dead grass, and (c) higher in areas with increased living grass cover, and 4) females from southwest Montana and in the high-elevation sagebrush type primarily allocated nutrients from winter habitats, whereas females from central Montana and in the low-elevation sagebrush type primarily allocated nutrient sources from spring habitats for offspring formation. My findings highlight a unique breeding strategy for sage-grouse residing in high-elevation sagebrush landscapes. Results described herein will allow managers in southwest Montana, and other regions in the northern Rocky Mountains, to better manage sage-grouse and sage-grouse habitats.Item Nutrient allocation to egg formation of lesser scaup(Montana State University - Bozeman, College of Letters & Science, 2010) Cutting, Kyle Anthony; Chairperson, Graduate Committee: Jay J. RotellaLesser Scaup (Aythya affinis) populations have declined for nearly three-decades. Recent evidence suggests that decreases in habitat quality and availability of spring staging areas may have resulted in a decline of recruitment. Recently, stable isotopes analysis has emerged as a powerful ecological tool to measure the degree of cross-seasonal effects of birds. In 2006 through 2008 in southwestern Montana, I used carbon (13C) and nitrogen (15N) stable isotopes to assess how red blood cells (RBC), which is a proxy for stored body reserves (endogenous), change over time as local foods (exogenous) are consumed, and to estimate the relative contributions of endogenous reserves and exogenous foods for egg formation. From arrival through the egg laying period, 15N values of RBC decreased while 13C values became more stable, a pattern consistent with expectations of endogenous tissues equilibrating with local dietary sources. In 2006 and 2008, isotopic values for egg albumen and yolk protein were similar to those expected from local dietary sources, which indicated that most protein used for producing egg albumen and yolk protein was obtained on the breeding grounds (exogenous sources). In 2007, endogenous reserves contributed on average 26% and 10% more for producing albumen and yolk protein, respectively, than in 2006 and 2008 combined. Due to small differences in 13C values between female endogenous lipids upon arrival to the breeding grounds and those of local invertebrate lipids, it was not possible to separately estimate the contributions of endogenous and invertebrate lipids to egg lipid formation. My results suggest that local invertebrates and endogenous lipid reserves contributed on average 51% (SE = 7%) to egg lipid production. The remaining contributions to eggs were derived from local seed sources. Despite recent findings of reduced endogenous reserves during spring migration, results from the females in this study suggest that the amount of time that females spend on the breeding grounds prior to nest initiation may be adequate in some years to allow them to attain adequate exogenous foods for reproduction. Future isotopic research is now needed across latitudinal gradients, allowing length of prebreeding season to vary, while separating out the contribution from endogenous versus exogenous sources.