Theses and Dissertations at Montana State University (MSU)
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Item Connectivity in a montane river basin : salmonid use of a major tributary in the Smith River system(Montana State University - Bozeman, College of Letters & Science, 2015) Ritter, Thomas David; Chairperson, Graduate Committee: Alexander ZaleThe Smith River is a popular recreational sportfishery in western Montana, but salmonid abundances there are relatively low and limited by high summer water temperatures and low discharges. Smith River tributaries may serve as thermal refuges and also as important spawning and nursery areas. Tributaries unaltered by anthropogenic disturbances may be especially important. If so, maintaining connectivity between the main-stem river and its tributaries would be essential. Moreover, an understanding of salmonid habitat use and management in a stressed system could help identify potential climate change adaptation strategies and tactics. My goal was to determine the roles of a major undisturbed tributary in the life histories and movements of salmonids in a montane river basin. My focus was on Tenderfoot Creek, a remote, unaltered major tributary to the Smith River. A PIT-tag detection network monitored the seasonal movements of rainbow x cutthroat hybrid trout, Mountain Whitefish, Brown Trout, and Brook Trout. Abundances were estimated by electrofishing and snorkeling. Despite thermally stressful conditions in the Smith River, no tagged fish were directly observed using Tenderfoot Creek as a thermal refuge, although such use probably occurred at the confluence within the Smith River. Interchange between Tenderfoot Creek and the Smith River was common for Brown Trout, Mountain Whitefish, and rainbow x cutthroat hybrid trout and consisted mostly of spawning migrations. Some large, presumably dominant Brown Trout appeared to establish permanent territories within Tenderfoot Creek. Spawning effort by Mountain Whitefish and rainbow x cutthroat hybrid trout was high; about 7,568 Mountain Whitefish were observed in spawning aggregations in autumn and estimated abundance of rainbow x cutthroat hybrid trout juveniles (N = 25,127) was much higher than that of other taxa. Brown Trout also spawned in Tenderfoot Creek (159 redds counted in 2011 and 2012), and Brook Trout spawned in side channels and tributaries. Tenderfoot Creek is heavily used by Smith River fishes for spawning; maintaining its connectivity and habitat quality is therefore beneficial to recruitment to the Smith River fishery.Item Greater sage-grouse (Centrocercus urophasianus) habitat in central Montana(Montana State University - Bozeman, College of Agriculture, 2006) Woodward, Jennifer Kristy; Chairperson, Graduate Committee: Carl Wambolt.Greater sage-grouse (Centrocercus urophasianus) habitat was studied in central Montana primarily on Wyoming big sagebrush (Artemisia tridentata wyomingensis) dominated rangeland. The primary objective was to compare shrub and herbaceous parameters within (use, random or non-use) and between seasonal habitats (nest, brood, winter). Nesting occurred in areas with greater total shrub cover (15v13%) and height (28v26 cm), and taller live (12v11 cm) and residual grass (9v8 cm) than randomly available. The shrubs under which hens nested were taller (50v44 cm) and more productive (61v51 g) than random shrubs. Due to increased precipitation in 2005, total herbaceous (18v13%), grass (15v12%), and forb cover (7v3%), and live grass height (13v10 cm) were greater in 2005 than 2004. Brood and paired random sites were similar for all parameters. There was greater shrub height (29v25 cm), total herbaceous cover (19v16%), forb cover (15v13%), and live grass height (17v11cm) in 2005 than 2004. Shrub density (1.5v1.1/m2) and residual grass height (9v5 cm) were greater in 2004.Item The influence of landscape characteristics on duck nesting success in the Missouri Coteau Region of North Dakota(Montana State University - Bozeman, College of Letters & Science, 2003) Stephens, Scott Eugene; Chairperson, Graduate Committee: Jay J. Rotella; Mark S. Lindberg (co-chair)Because of the importance of nesting success to avian population dynamics, and the extensive and ubiquitous nature of habitat fragmentation, many studies have attempted to address the relationship between fragmentation and nesting success. However, an overall theory of fragmentation effects on nesting success has remained elusive. First, we reviewed published literature to examine fragmentation effects on nesting success at three spatial scales (i.e., edge, patch, and landscape scales). We identified 86 relevant manuscripts that provided 117 individual tests of hypotheses regarding the effects of fragmentation on nesting success. Fragmentation effects were more likely to be detected if fragmentation was examined at a landscape scale and if research was conducted over several years. Next, we examined the influence of habitat and landscape variables on duck nest survival (n ~ 4200 nests) on 18 10.4-km2 sites in the Missouri Coteau Region of North Dakota. We evaluated competing models of nest survival that considered combinations of habitat features measured at nests, within nesting patches, and at multiple landscape scales. We used generalized non-linear mixedmodeling techniques to model nest survival. Information-theoretic techniques were used to select among competing models. Models that included random effects of individual sites and covariates measured at multiple landscape scales were dramatically better than models that included nest-level, patch-level, or landscape-scale covariates measured at a single spatial scale. Nest survival was positively related to the amount of grassland habitat, negatively related to the wetland density and related to the amount of grassland edge in a complex quadratic manner. Finally, we combined our nest survival model with existing models of mallard pairs using spatially-explicit GIS models and applied them to the entire Coteau region of North and South Dakota to guide conservation programs. Important trade-offs existed between pair density and nest survival; source populations were dominated by low pair-density areas while sink populations were dominated by high and medium pair-density areas. Based on the complex suite of factors influencing nest survival, a unifying paradigm of fragmentation across taxa and habitat types may not exist. Thus, research on the species and habitats of interest may be necessary to guide successful conservation efforts.Item Breeding ecology, survival rates, and causes of mortality of hunted and nonhunted greater sage-grouse in central Montana(Montana State University - Bozeman, College of Letters & Science, 2006) Sika, Jenny Lyn; Chairperson, Graduate Committee: Jay J. RotellaDeclines in productivity have been implicated in population declines for greater sage-grouse (Centrocercus urophasianus) in several areas, but there is considerable variation in reproductive effort, reproductive success and female survival, both temporally and spatially, and more data are needed. Despite declining populations, sage grouse are still legally harvested in most of their current range, including Montana, and uncertainty about how harvest impacts sage grouse vital rates remains. The reproductive activity, survival rates, and causes of mortality of hunted and nonhunted sage grouse females were monitored year round using radio-telemetry in central Montana during 2004 and 2005. Data on nest survival and brood survival were also collected. Nest survival was greater for renests, 0.56, than for first nests, 0.32. Brood survival to 30 days posthatch was estimated as 0.79. Reproductive effort and reproductive success were higher in 2005. Female survival during the nesting season was constant, 0.94 monthly.