Catalogue Search | MBRL
Search Results Heading
Explore the vast range of titles available.
MBRLSearchResults
-
LanguageLanguage
-
SubjectSubject
-
Item TypeItem Type
-
DisciplineDiscipline
-
YearFrom:-To:
-
More FiltersMore FiltersIs Peer Reviewed
Done
Filters
Reset
17
result(s) for
"Milligan, Megan C."
Sort by:
Habitat selection of female sharp-tailed grouse in grasslands managed for livestock production
by
McNew, Lance B.
,
Berkeley, Lorelle I.
,
Milligan, Megan C.
in
Animal behavior
,
Animal husbandry
,
Beef cattle
2020
Habitat selection links individual behavior to population abundance and dynamics, so evaluation of habitat selection is necessary for conservation and management. Land management can potentially alter both the structure and composition of habitats, thus influencing habitat selection and population size. Livestock grazing is the dominant land use worldwide and, while overstocking has been linked to the decline of many wildlife species, properly managed grazing could improve habitat quality and maintain native rangeland habitats. We evaluated breeding season habitat selection of female sharp-tailed grouse, an indicator species for grassland ecosystems, in relation to grazing management and landscape features in eastern Montana and western North Dakota. At broad spatial scales, females selected for multiple landscape features, including grassland, but exhibited no selection for either landscape or management variables when selecting habitat at smaller spatial scales. Females selected for pastures managed with rest-rotation grazing when choosing a home range, but selection did not equate to improved fitness. Moreover, we observed strong individual variation in both home range size and third-order habitat selection. While the high variability among individuals makes specific management recommendations difficult, selection for grassland habitats at broad scales suggests that strategies that maintain intact native rangelands are important for the conservation of sharp-tailed grouse.
Journal Article
Linking resource selection to population performance spatially to identify species' habitat across broad scales: An example of greater sage‐grouse in a distinct population segment
by
Casazza, Michael L.
,
Mathews, Steven R.
,
Brussee, Brianne E.
in
Animal reproduction
,
Applied Ecology
,
Brood rearing
2024
Management decisions often focus on the habitat selection of marked individuals without considering the contribution to demographic performance in selected habitats. Because habitat selection is not always adaptive, understanding the spatial relationship between habitat selection and demographic performance is critical to management decisions. Mapping both habitat selection and demographic performance for species of conservation concern can help guide population‐scale conservation efforts. We demonstrate a quantitative approach to differentiate areas supporting selection and survival at large spatial extents. As a case study, we applied this approach to greater sage‐grouse (Centrocercus urophasianus; hereafter, sage‐grouse), an indicator species for sagebrush ecosystems. We evaluated both habitat selection and survival across multiple reproductive life stages (nesting, brood‐rearing) in the Bi‐State Distinct Population Segment, a genetically distinct and geographically isolated population of sage‐grouse on the southwestern edge of the species' range. Our approach allowed us to identify both mismatches between selection and survival and trade‐offs between reproductive life stages. These findings suggest resource demands vary across time, with predation risk being a dominant driver of habitat selection during nesting and early brood‐rearing periods when chicks are smaller and flightless, whereas access to forage resources becomes more important during late brood rearing when resources become increasingly limited. Moving beyond identifying and managing habitat solely based on species occupancy or use by incorporating demographic measures allows managers to tailor actions to their specific goals; for example, protections of areas that support high selection and high survival and restoration actions focused on increasing survival in areas of high selection and low survival. Habitat selection is not always adaptive, so understanding the link between habitat selection and demographic performance is critical to management decisions. We evaluated both selection and survival across multiple reproductive life stages in a genetically distinct and geographically isolated population of greater sage‐grouse, an indicator species for sagebrush ecosystems. Our approach allowed us to identify both mismatches between selection and survival and trade‐offs between life stages.
Journal Article
Variable effects of wind‐energy development on seasonal habitat selection of pronghorn
by
Wallace, Cody
,
Smith, Kurt T.
,
Beck, Jeffrey L.
in
Alternative energy sources
,
Animal populations
,
Antilocapra americana
2021
In the face of climate change, wind energy represents an important alternative to oil and gas extraction to meet increasing energy demands, but it has the potential to disrupt wildlife populations. Because behavioral adjustments, such as altered habitat selection, are a primary way that long‐lived species respond to novel disturbances, we evaluated effects of wind energy development on pronghorn (Antilocapra americana) space use and habitat selection. Using data from GPS‐collared female pronghorn in the Shirley Basin of south‐central Wyoming, USA, we tested four potential effects of wind turbines on pronghorn space use during the summer and winter: (1) displacement away from wind turbines, (2) increase in size of home ranges, (3) short‐term avoidance behavior within home ranges, and (4) changes in avoidance behavior within home ranges over time. We monitored 166 individuals over five summers (2010, 2011, 2018, 2019, and 2020) and 142 individuals over five winters (2009/2010, 2010/2011, 2011/2012, 2018/2019, and 2019/2020) and used resource selection functions to evaluate selection relative to turbines after controlling for other habitat factors, such as snow depth. Although a lack of consistent negative effects of wind turbines on pronghorn across years suggested that wind energy development may have less severe and more intermittent effects on pronghorn than oil and gas development has had on other ungulates, there was a trend toward increased displacement during the study and behavioral avoidance was apparent for individuals in close proximity to turbines. However, pronghorn were highly variable in their fine‐scale habitat selection, across both individuals and years, which could make effects of wind energy development difficult to detect. Nevertheless, some individuals, particularly those close to wind‐energy facilities, did avoid turbines, which could translate to population‐level behavioral or demographic changes over time and affect the resilience and stability of the population. Over time, the accumulation of development, including wind turbines, roads, and fences, can both limit movement and fragment habitat, potentially reaching a critical threshold beyond which populations are negatively impacted.
Journal Article
Moisture abundance and proximity mediate seasonal use of mesic areas and survival of greater sage‐grouse broods
by
Casazza, Michael L.
,
Coates, Peter S.
,
Severson, John P.
in
Anthropogenic factors
,
Centrocercus urophasianus
,
climate
2022
Water is a critical and limited resource, particularly in the arid West, but water availability is projected to decline even while demand increases due to growing human populations and increases in duration and severity of drought. Mesic areas provide important water resources for numerous wildlife species, including the greater sage‐grouse (Centrocercus urophasianus; hereafter, sage‐grouse), an indicator for the health of sagebrush ecosystems. Understanding how wildlife use these crucial areas is necessary to inform management and conservation of sensitive species. Specifically, the influence of anthropogenic water subsidies such as irrigated pastures is not well‐studied. We evaluated brood‐rearing habitat selection and brood survival of sage‐grouse in Long Valley, California, an area where the water rights are primarily owned by the city of Los Angeles and water is used locally to irrigate for livestock. This area thus represents a unique balance between the needs of wildlife and people that could increasingly define future water management. In this study, sage‐grouse broods moved closer to the edge of mesic areas and used more interior areas during the late brood‐rearing period, selecting for greener areas after 1 July. Mesic areas were particularly important during dry years, with broods using areas farther interior than in wet years. Brood survival was also positively influenced by the availability and condition of mesic resources, as indicated by variation in values of normalized difference vegetation index (NDVI), with survival peaking at moderate values of NDVI and just outside the edge but decreasing inside the mesic areas. Our results highlight the importance of quality edge habitat of large mesic areas for sage‐grouse to balance habitat selection and survival, particularly during drier years and during the late brood‐rearing period, which is a critical period because chick survival has been shown to influence population growth. This study highlights the implications of large‐scale anthropogenic water manipulation, and the balance between local irrigation and water distribution to benefit other regions, from the context of a species of high conservation concern in North American sagebrush ecosystems. Mesic areas are critical resources for wildlife populations, are currently in decline, and are often managed by humans. We studied the influence of variability in vegetation productivity (NDVI) on Greater sage‐grouse, a sagebrush ecosystem indicator species, within and adjacent to mesic resources primarily managed by the city of Los Angeles, CA, USA. Availability and condition of mesic resources depended on drought and human usage, and had compelling but complex relationships with sage‐grouse brood habitat selection and survival. Conditions along mesic habitat edges represented a key feature influencing this important life stage.
Journal Article
Survival of Sharp-Tailed Grouse Under Variable Livestock Grazing Management
by
BERKELEY, LORELLE I.
,
MCNEW, LANCE B.
,
MILLIGAN, MEGAN C.
in
adults
,
Agricultural land
,
Andersen‐Gill
2020
Livestock grazing is a predominant land use worldwide and can influence wildlife populations by altering grassland composition, structure, and productivity. Conceptually, rest-rotation livestock grazing could increase pasture-level heterogeneity that would allow wildlife to balance the need for resources with the risk of predation. Prairie-grouse (Tympanuchus spp.) are recognized as important indicator species for grassland ecosystems, so identifying management approaches suitable for prairie-grouse could have implications for other species. We monitored radio-collared female sharp-tailed grouse (T. phasianellus) to evaluate the effects of 3 systems of livestock grazing management on the breeding season survival and habitat-associated mortality risk of adult grouse in the northern mixed-grass prairie in eastern Montana and western North Dakota, USA, during 2016–2018. Cumulative breeding season survival was 0.65 ± 0.04 (SE) and annual survival varied from 0.28 ± 0.04 to 0.50 ± 0.05. Grazing management did not have a meaningful influence on any aspect of the cumulative breeding season survival of adult female sharp-tailed grouse, although the seasonal timing of peaks in mortality risk differed among systems. A 10% increase in cropland increased mortality risk of adult female sharp-tailed grouse by a factor of 1.27. Overall, our results suggest that strategies that preserve economically viable ranching systems in unfragmented grasslands may have greater benefits for sharp-tailed grouse survival than prescriptive livestock grazing systems.
Journal Article
Wind‐energy development alters pronghorn migration at multiple scales
by
Wallace, Cody
,
Beck, Jeffrey L.
,
Cufaude, Teal
in
Animal migration
,
Anthropogenic factors
,
Antilocapra americana
2023
Migration is a critical behavioral strategy necessary for population persistence and ecosystem functioning, but migration routes have been increasingly disrupted by anthropogenic activities, including energy development. Wind energy is the world's fastest growing source of electricity and represents an important alternative to hydrocarbon extraction, but its effects on migratory species beyond birds and bats are not well understood. We evaluated the effects of wind‐energy development on pronghorn migration, including behavior and habitat selection, to assess potential effects on connectivity and other functional benefits including stopovers. We monitored GPS‐collared female pronghorn from 2010 to 2012 and 2018 to 2020 in south‐central Wyoming, USA, an area with multiple wind‐energy facilities in various stages of development and operation. Across all time periods, we collected 286 migration sequences from 117 individuals, including 121 spring migrations, 123 fall migrations, and 42 facultative winter migrations. While individuals continued to migrate through wind‐energy facilities, pronghorn made important behavioral adjustments relative to turbines during migration. These included avoiding turbines when selecting stopover sites in spring and winter, selecting areas farther from turbines at a small scale in spring and winter, moving more quickly near turbines in spring (although pronghorn moved more slowly near turbines in the fall), and reducing fidelity to migration routes relative to wind turbines under construction in both spring and fall. For example, an increase in distance to turbine from 0 to 1 km translated to a 33% and 300% increase in the relative probability of selection for stopover sites in spring and winter, respectively. The behavioral adjustments pronghorn made relative to wind turbines could reduce the functional benefits of their migration, such as foraging success or the availability of specific routes, over the long term. Wind energy is the world's fastest growing source of electricity and represents an important alternative to hydrocarbon extraction, but its effects on migratory species beyond birds and bats are not well understood. We found that while connectivity was not lost and pronghorn continued to migrate through wind‐energy facilities, pronghorn made important behavioral adjustments relative to turbines during migration. These included avoiding turbines when selecting stopover sites, selecting areas farther from turbines at a small scale, moving more quickly near turbines in the spring, and reducing fidelity to migration routes relative to wind turbines under construction.
Journal Article
Habitat quality and nest-box occupancy by five species of oak woodland birds
2016
Habitat quality can have important consequences for avian communities through impacts on survival and annual reproductive success. However, habitat quality is often hard to measure, leading to the use of occupancy as a proxy. We compared habitat use of 5 avian species that used nest boxes in the oak woodlands of central coastal California, USA, to determine which habitat characteristics best predicted box occupancy. We focused on the relationship between habitat characteristics and occupancy for five species—Ash-throated Flycatcher (Myiarchus cinerascens), House Wren (Troglodytes aedon), Oak Titmouse (Baeolophus inornatus), Violet-green Swallow (Tachycineta thalassina), and Western Bluebird (Sialia mexicana)—for which we had 12 consecutive years of data on nest boxes spread over a 700 ha study area. We also examined whether the physical habitat characteristics and box occupancy rates were good predictors of reproductive success, to infer whether they were useful indicators of habitat quality. The habitat characteristics influencing nest-box occupancy differed among the 5 species. Ash-throated Flycatchers were associated with fragmented habitats with less grassland. House Wrens were associated with riparian vegetation, as were Oak Titmice, which were also associated with chaparral. Violet-green Swallows were associated with chaparral but tended to nest farther from riparian corridors than Oak Titmice. Western Bluebirds nested away from riparian corridors and in areas with more grassland and oak woodland. Finally, occupancy rate was a better predictor than habitat characteristics of reproductive success, which suggests that occupancy can be a valuable proxy for habitat quality for these 5 species.
Journal Article
EFFECTS OF SCAVENGING ON ASSUMPTIONS OF MORTALITY ANALYSES OF RADIO-MARKED GAMEBIRDS
2019
Survival estimation is critical to studies of wildlife population biology, and recent model developments allow for temporal covariates on mortality risk. To test model assumptions that scavengers do not influence either perceived mortality cause or location, we randomly placed 24 radio-marked Chukar (Alectoris chukar) carcasses over gradients of grassland habitat conditions in eastern Montana in both April 2017 and July 2018, and monitored scavenging activity at intervals relevant to gamebird telemetry studies. High rates of scavenging (12.5–78%, depending on season and relocation interval) suggest that scavenging activity could confound determination of cause-specific mortality, but that its influence varies with season. Scavenging activity did not significantly influence perceived mortality locations regardless of season or local habitat conditions with a relocation interval of 3 d (8% of carcasses moved), but mortality locations may be biased over longer periods (50% of carcasses moved in 7-d period), particularly in warm seasons or regions.
Journal Article
What Should Go in a Wildlife Professional’s Geospatial Toolbox?
by
LEE J. HECKER
,
MATTHEW DELHEIMER
,
BROOKE BERGER
in
ArcGIS
,
connectivity
,
Geographic Information System
2017
Geospatial tools have become a critical component to most wildlife studies and management questions. With a diversity of approaches available, current and future wildlife professionals deserve guidance on the most important tools to answer these questions. Younger professionals may be expected to know a separate set of skills from those required further on in their career. We conducted an online survey and a yearlong search of job advertisements to identify the most important geospatial approaches, techniques, programs, and ancillary skills for wildlife professionals. We provide the results of these 2 efforts so that wildlife professionals interested in geospatial tools can prioritize those most valued in our field. Habitat modeling and home range analysis were the 2 highest-ranked tools. Highly ranked programs included ArcGIS, R, Google Earth, and Geospatial Modeling Environment. We suggest that wildlife professionals should have a geospatial program they are comfortable with and be conversant with the major approaches (e.g., habitat modeling, home range analysis, remote sensing, andmobile mapping) but need not be experts in each field. Younger professionals should focus on the “big picture” tools such as ArcGIS, while professionals further in their career are expected to have some expertise in multiple areas, including knowledge of current and emerging trends.
Journal Article