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Item Greater sage-grouse (Centrocercus urophasianus) nest survival and nest predator response to fence modifications in a grazing modified landscape(Montana State University - Bozeman, College of Agriculture, 2023) O'Harra, Aaron William; Chairperson, Graduate Committee: Bok Sowell; This is a manuscript style paper that includes co-authored chapters.Livestock operations are present across much of the greater sage-grouse (Centrocercus urophasianus; sage-grouse) current range and the infrastructure associated with this land-use type can have negative effects on sage-grouse populations. Recent work has found that the daily survival rate of nests placed close to fences experience a 4-fold decrease in survival probability. The reduction in survival was theorized to be attributed to higher use of fences by predators due to increased movement efficiency and foraging rates predators experience along linear features. In this study, we experimentally modified fences to reduce perch availability and the barrier effects often associated with fences to improve sage-grouse nest survival. We monitored 177 nests over 8 years to assess the effectiveness of this management technique. We also used camera traps and point count surveys in the last 3 years of the study to assess the occurrence of three common sage-grouse nest predators; badgers (Taxidea taxus), coyotes (Canis latrans), and avian predators. We modeled daily nest survival against modified and traditional fences and landscape features throughout our study area in a Bayesian framework. Our predator occurrence rates were modeled using a single season occupancy model in relation to similar landscape features used for nest survival modeling. We detected evidence of an increase in nest survival of 11.4% (90% CRI: 3.2%, 20.0%) for sage grouse nests placed closer to modified fences (mean survival = 35.8%) when compared to traditional fence types (mean survival = 24.4%). We also found evidence for a 14% (95% CI: 5%, 23%) decrease in badger occurrence and a 15% (95% CI: 12%, 18%) increase in coyote occurrence along recently modified fences. We found no evidence that avian predators used fences more than areas with no fence present. Our results may be influenced by the distribution of fence types between sagebrush species. Our results indicate that predation risk for sage-grouse nests across a landscape is predator specific. We conclude that modifying fences in this way can improve sage-grouse nest survival, and the effectiveness of these modifications is controlled by a combination of the predators and landscape features associated with a nest site.Item Associations of broad scale vegetation characteristics and abundances, nest densities, and nest survival of mixed-grass prairie songbirds in northern Montana(Montana State University - Bozeman, College of Agriculture, 2019) Pulliam, John Patrick; Chairperson, Graduate Committee: Lance McNewGrassland bird populations are declining faster than any other avian guild. In northern Montana, four species are experiencing severe population declines: Baird's sparrow (Centronyx bairdii), chestnut-collared longspur (Calcarius ornatus), McCown's longspur (Rynchophanes mccownii), and Sprague's pipit (Anthus spragueii). In 2017 and 2018, I evaluated abundance, nest density and nest survival of these species in relation to local vegetative conditions with the goal of identifying important breeding season vegetation conditions to inform management. I conducted fixed-radius point-counts at 100 sites to estimate local abundance, rope drag surveys to estimate nest density, nest monitoring to estimate nest survival, and vegetation surveys to estimate vegetation structure and composition across grassland habitats in Phillips County, MT. Point-counts and rope drag surveys were carried out with replicated visits to allow estimation of species-specific detection probabilities. Vegetation conditions were measured at the plot level (9-ha) to provide information at scales relevant for land managers. The abundance of Baird's sparrows was positively associated with residual grass cover and litter cover. Chestnut-collared longspur abundance was negatively associated with residual grass, exotic grass, and shrub cover and had a quadratic relationship with biomass. Plot-level abundance of McCown's longspurs was negatively associated with both shrub cover and biomass. Sprague's pipit abundance declined with exotic grass cover and exhibited a quadratic relationship with biomass. Limited sample size only allowed inference of nest density and nest survival for chestnut-collared longspurs. Nest density was negatively associated with plot scale exotic grass cover, biomass, and slope. I did not find support for any vegetation covariates on nest survival for chestnut-collared longspurs. These results provide some guidance for landscape managers interested in improving habitat for these species. The contrasting results among species, however, emphasize the need for heterogeneity in vegetation structure and composition. The disconnect between relevant covariates for nest density and nest survival suggest possible maladaptation for chestnut-collared longspurs. This result suggests that an index of productivity for this species that does not include both nest density and nest survival may produce erroneous results.Item Nest site selection and brood home ranges of greater sage-grouse (Centrocercus urophasianus) in the Centennial Valley, Montana(Montana State University - Bozeman, College of Agriculture, 2016) Schroff, Sean Rudolf; Chairperson, Graduate Committee: Bok Sowell; Kyle A. Cutting, Craig A. Carr, Michael R. Frisina, Lance B. McNew and Bok F. Sowell were co-authors of the article, 'Fine-scale nest site selection of greater sage-grouse (Centrocercus urophasianus) in the Centennial Valley, Montana' submitted to the journal 'The condor' which is contained within this thesis.; Kyle A. Cutting, Craig A. Carr, Michael R. Frisina and Bok F. Sowell were co-authors of the article, 'Brood home range sizes of greater sage-grouse in response to cattle grazing in the Centennial Valley, Montana' submitted to the journal 'The condor' which is contained within this thesis.The purpose of this study was to estimate the fine-scale nest site selection of greater sage-grouse (Centrocercus urophasianus) and to investigate the differences in brood home range size in response to cattle grazing in the Centennial Valley, Montana. A total of 111 sage-grouse hens were captured across two breeding seasons (2014-2015). Hens were captured on leks using spotlighting/dip netting techniques. A total of 90 nests were found across both breeding seasons using radio-collared sage-grouse (VHF). Vegetation surveys were conducted at nests and random sites that measured the nest shrub and the cover within 3 m of the nest. All habitat variables that were included in the top model (GLMs) were nest shrub morphological characteristics and the cover provided by the nest shrub. It appears that sage-grouse are selecting nest sites based on the concealment provided by the nest shrub. Forty-five percent of nests were under mountain big sagebrush plants (Artemisia tridentata ssp. vaseyana), 21% nests were under three-tip sagebrush (A. tripartita), and 20% of nests were under basin big sagebrush plants (A. tridentata ssp. tridentata). Nests under mountain big sagebrush and three-tip sagebrush shrubs provided twice the amount of lateral cover that basin big sagebrush provided. Of the 90 nests found, 18 produced successful broods. Grazing utilization levels, grass heights, and dominant sagebrush type were recorded at brood locations and extrapolated to estimate those values across the brood's home range. Two sample t-tests were used to test if there was a difference between the habitat variables in grazed and ungrazed pastures as well as by habitat type. Grazing utilization levels were on average 4% in brood home ranges across both years of the study. There was no year effect in brood home range size and brood home range size did not differ by grazed and ungrazed pastures or across the two habitat types the broods used. Brood home range size is most likely delineated by other factor(s) besides cattle grazing. Managers should focus on conserving continuous stands of mountain big sagebrush and three-tip sagebrush habitats because they provide higher concealment for nesting and were highly used for brood-rearing.Item Sage-grouse (Centrocercus urophasianus) nesting and brood-rearing sagebrush habitat characteristics in Montana and Wyoming(Montana State University - Bozeman, College of Agriculture, 2005) Lane, Vanessa Rae; Chairperson, Graduate Committee: Bok F. Sowell.Nesting and brood-rearing habitat data for greater sage-grouse (Centrocercus urophasianus) near Roundup in central Montana in 2004, Decker in south-central Montana and northern Wyoming in 2003, and Malta in north-central Montana in 2003 was collected. Sage-grouse hens were fitted with radio collars and tracked to nests. Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) canopy cover, density, and height for nest vs. random sites and brood vs. random sites were compared to determine if hens were selecting for these parameters. Forb, grass, total herbaceous, and residual cover, grass height, and residual height were also compared. Nest sites near Roundup (53 nest sites), Decker (58), and Malta (45) were measured. Most nest sites near Roundup were in sagebrush (91 %). All nest sites near Decker and Malta were in sagebrush. Only nest sites in sagebrush habitats were analyzed. Nest sites had taller (48 vs. 42 cm, P ¡Ü 0.01) and more productive (60 vs. 46 g of produced forage, P ¡Ü 0.01) nest shrubs than random sites near Roundup. At the Decker study area, nest sites had greater sagebrush cover (22 vs. 14 %, P ¡Ü 0.01), density (1.1 vs. 0.6 shrubs per m2, P ¡Ü 0.01), and taller shrubs within 15 m (52 vs. 42 cm, P ¡Ü 0.01) than random sites. Nest sites had taller shrubs within 15 m of the nest (30 vs. 26 cm, P ¡Ü 0.05) near Malta. Successful and failed nest sites did not differ between the Roundup and Decker study areas. Yearling nest sites had shorter grass than adult sites in Roundup (9 vs. 11 cm, P ¡Ü 0.05). Forty-four brood sites near Roundup and 73 brood sites near Decker were measured. Brood sites were not measured near Malta. Most brood sites near Roundup (71 %) and all near Decker (100 %) were in sagebrush. Only brood sites in sagebrush habitats were analyzed. Vegetation was similar between brood and paired random sites near Roundup. At the Decker study area, brood sites had denser sagebrush (1.1 vs. 0.6 shrubs per m2, P ¡Ü 0.01) than random sites. Adult and yearling hen brood sites did not differ near Roundup. Adult brood sites had greater sagebrush cover (14 vs. 8 %, P ¡Ü 0.05), density (1.0 vs. 0.6 shrubs per m2, P ¡Ü 0.05), and taller shrubs within 15 m (44 vs. 37 cm, P ¡Ü 0.05) than yearling sites near Decker. Brood sites had less shrub cover at 4 weeks than weeks 1 and 2 (10 vs. 16 and 17 %, P ¡Ü 0.01) near Roundup. Sagebrush habitats comprised 97 % (151 of 156) of the total nest sites and 92 % (108 of 117) of all brood locations. Nest sites had 19·C22 % sagebrush cover, 26·C52 cm sagebrush heights, and total herbaceous cover of 13·C33 %. Brood sites had 12-13 % sagebrush cover, 22·C43 sagebrush heights, and 14·C33 % total herbaceous cover. This study reinforces the importance of sagebrush habitats for nesting and brood-rearing sage-grouse. Management practices which remove this shrub would probably reduce the nesting and brood-rearing success of sage-grouse in central Montana and northern Wyoming.