Theses and Dissertations at Montana State University (MSU)
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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 Can targeted cattle grazing increase abundance of forbs or arthropods in sage-grouse brood-rearing habitat?(Montana State University - Bozeman, College of Agriculture, 2018) Payne, Jarrett MacKenzie; Chairperson, Graduate Committee: Jeffrey C. MosleySuboptimal brood-rearing habitat often limits greater sage-grouse (Centrocercus urophasianus) populations in western North America. In mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana [Rydb.] Beetle) brood-rearing habitat, dense sagebrush canopy cover (> 25% cover) may limit the understory forbs and arthropods that sage-grouse prefer to eat during summer. Targeted cattle grazing is a potential habitat management tool to reduce dense sagebrush. This study evaluated targeted cattle grazing on a landscape scale to increase forbs and arthropods within core sage-grouse brood-rearing habitat. Objectives of this study were to evaluate how well targeted cattle grazing reduced mountain big sagebrush canopy cover, increased forb abundance and diversity, and increased arthropod abundance. Targeted cattle grazing was applied within two large, contiguous pastures (625 ha each) in the Beaverhead Mountains of southwestern Montana. The two pastures were grazed simultaneously at a light stocking rate (6.25 ha/AUM) for two weeks each year in mid-October 2015 and 2016. Vegetation and arthropod responses were measured during the following June-early July (2016 and 2017, respectively) within 32 microsites where mountain big sagebrush canopy cover exceeded 30% pre-treatment. Microsites were 0.008 ha to match the spatial scale at which sage-grouse broods select fine-scale habitat. One of two treatments was randomly assigned to each microsite: a low moisture block protein supplement or no supplement (unsupplemented). In the first summer after treatment, supplemented microsites averaged 78% less sagebrush canopy cover (8% vs. 36%; P < 0.001) and 25% more forb canopy cover (15% vs 12%; P = 0.122). Sage-grouse forb canopy cover was 50% greater in supplemented microsites (3% vs. 2%; P = 0.003). Forbs also comprised a greater proportion of the herbaceous understory in the supplemented vs. unsupplemented sites (48% vs. 36%; P = 0.002). Arthropod abundances were greater in supplemented than unsupplemented microsites only during the wet year of 2017 when arthropods were 1.7-1.8x more abundant in supplemented microsites. Sagebrush canopy cover was reduced by cattle trampling, not browsing. My results demonstrate that targeted cattle grazing can increase abundance of forbs and arthropods in mesic, dense stands of mountain big sagebrush in sage-grouse brood-rearing habitat.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.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.