South Greeley, WY, United States
South Greeley, WY, United States

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Webb S.L.,Hayden Wing Associates LLC | Dzialak M.R.,Tetra Tech Inc. | Kosciuch K.L.,Hayden Wing Associates LLC | Winstead J.B.,Hayden Wing Associates LLC
Rangeland Ecology and Management | Year: 2013

Areas identified as winter range are important seasonal habitats for mule deer (Odocoileus hemionus) because they can moderate overwinter mortality by providing thermal cover and forage. Therefore, identifying seasonally important resources is a conservation priority, especially when sensitive areas are proposed for development. We used data collected from global positioning system (GPS) collars fitted on female mule deer (n=19; one location every 3 h) to identify resources important during winter (23 February 2011-30 April 2011; 1 November 2011-15 January 2012) in a region spanning southern Wyoming and northern Colorado that has been proposed for wind energy development. The study period included portions of two consecutive winters but were pooled for analysis. We used methods to account for GPS biases, fractal analyses to determine perceived spatial scale, and discrete choice models and conditional logistic regression to assess resource selection prior to development (i.e., baseline data). Resource selection by female mule deer revealed similar patterns between active (0600-1800 hours) and nonactive (2100-0300 hours) periods. Deer selected most strongly for proximity to rock outcrops and shrubland and average values of slope. Deer tended to avoid roads and grasslands; all other landscape features had minimal influence on resource selection (hazard ratios near, or overlapping, 1). Using the fixed-effects coefficient estimates, we developed two spatially explicit maps that depicted probability of mule deer occurrence across the landscape. Based on an independent validation sample, each map (active and nonactive) validated well with a greater percentage of locations occurring in the two highest probability of use bins. These maps offer guidance to managing mule deer populations, conserving important seasonal habitats, and mitigating development (e.g., wind energy) in areas identified as important to mule deer. © 2013 The Society for Range Management.

Dzialak M.R.,Hayden Wing Associates LLC | Webb S.L.,Hayden Wing Associates LLC | Harju S.M.,Hayden Wing Associates LLC | Winstead J.B.,Hayden Wing Associates LLC | And 3 more authors.
Landscape Ecology | Year: 2011

Prioritizing habitat for animal conservation in heterogeneous landscapes requires an understanding of where animal occurrence coincides with human influences on demographic performance. We related broad-scale patterns of occurrence with risk of mortality among female Rocky Mountain elk (Cervus elaphus) in a human-modified landscape to develop a spatially-explicit framework for animal conservation at the landscape level. Variability in the spatial pattern of elk occurrence was driven by preference for specific habitat types as well as responses to human activity. In contrast, risk of mortality was a function of human modification of the landscape with little variation explained by habitat. Proximity to industrial development was associated with increased risk of mortality whereas proximity to residences and agricultural structures was associated with decreased risk. Individual-level results revealed added complexity, whereby risk of mortality was associated with a consistent pattern of occurrence relative to industrial development, yet the association between risk and occurrence relative to structures was highly variable and likely a function of disparate land-use priorities. Approaches to managing human-mediated risk at the landscape level are most effective when they decompose human activity into constituent parts influencing risk, and when individual variation relative to the population response is investigated. Conservation interventions need to target factors that have a consistent influence across the population rather than risk uncertainty that would arise from targeting factors that influence individuals in variable or situation-specific ways. The spatial tools developed herein provide guidance for sustainable landscape planning in the study area, while the concept of linking occurrence and demographic performance within a hierarchical modeling framework has general application for animal conservation in landscapes subject to change, human-caused or otherwise. © 2011 Springer Science+Business Media B.V.

Webb S.L.,Hayden Wing Associates LLC | Dzialak M.R.,Hayden Wing Associates LLC | Harju S.M.,Hayden Wing Associates LLC | Hayden-Wing L.D.,Hayden Wing Associates LLC | Winstead J.B.,Hayden Wing Associates LLC
Wildlife Research | Year: 2011

Context. Many ungulate species exhibit strong site fidelity to previously established areas, particularly females. However, development of the landscape may cause animals to shift their distribution to more secure areas. Aims. To determine range use dynamics (i.e. size and overlap of core areas and home ranges) of female elk (Cervus elaphus) relative to land development features (e.g. roads, well pads, buildings, developments, towns, etc.) after controlling for environmental features (i.e. forest cover). Methods. During the four-year study, we fitted elk (n = 165) withGPScollars annually and programmed collars to attempt one location fix every 3 h (eight locations per day) for one year. Females (n = 18) were subsequently recaptured and refitted with GPS collars to provide range use dynamics of individual elk over two to three years. We calculated sizes of core areas and home ranges using adaptive kernel estimators, overlap between annual ranges, and establishment of ranges relative to land development. Key results. Overlap of annual core areas (48.6%) and home ranges (67.9%) was high despite annual increases in land development. Sizes of core areas and home ranges and annual overlap (i.e. site fidelity) were negatively influenced by land development after controlling for forest cover. Conclusions. These data reveal that female elk show high levels of site fidelity even in the presence of increasing annual land development. Females did not appear to abandon previously established areas, but used ranges in a manner that minimised interaction with development within these areas based on reductions in range use size and fidelity as land development increased. Implications. To help mitigate impacts on elk, land development should be minimised and large areas of forest protected so elk can avoid areas associated with human activity. © CSIRO 2011.

Hess J.E.,University of Wyoming | Hess J.E.,Hayden Wing Associates LLC | Beck J.L.,University of Wyoming
Wildlife Society Bulletin | Year: 2012

Wyoming big sagebrush (Artemisia tridentata wyomingensis) treatments are often implemented to improve breeding habitat for greater sage-grouse (Centrocercus urophasianus), a species of considerable conservation concern. In 2008 and 2009, we measured vegetation structure available to sage-grouse for breeding at 19 sites that were prescribed burned during 1990-1999 and 2000-2006, 6 sites that were mowed during 2000-2006, and 25 paired, untreated reference sites in the Bighorn Basin of north-central Wyoming, USA We compared minimum guidelines for canopy cover and height of Wyoming big sagebrush and perennial grass in arid greater sage-grouse breeding habitat (Connelly et al. 2000b) to measurements at our sampling sites. Sagebrush canopy cover and height at reference sites met the minimum guidelines. Sagebrush canopy cover at burned and mowed sites did not meet the minimum guideline, except for sites mowed on aridic soilsmeasured during 2009. Burned and mowed (3 of 4 cases) sagebrush did not meet minimum height for breeding up to 19 yr and 9 yr post-treatment, respectively. Perennial grass canopy cover and height met the minimum guidelines for breeding habitat at reference, burned, and mowed sites. Burning increased grass canopy cover, but not height, compared to reference sites in 2 of 8 instances. Because burning, but not mowing, infrequently enhanced grass cover, but not height, and sagebrush structure was reduced by both practices for long periods, managers should consider how treatments may negatively affect Wyoming big sagebrush communities for sage-grouse and consider other practices, including continued nontreatment and improved livestock grazing, to increase grass cover and height. © © 2012 The Wildlife Society.

Webb S.L.,Hayden Wing Associates LLC | Dzialak M.R.,Hayden Wing Associates LLC | Wondzell J.J.,Hayden Wing Associates LLC | Harju S.M.,Hayden Wing Associates LLC | And 2 more authors.
Population Ecology | Year: 2011

Animal populations are becoming increasingly exposed to human activity as human populations expand and demand for energy resources (e. g., coal, oil and natural gas) increases. We initiated this study to document survival and cause-specific mortality patterns of female Rocky Mountain elk (Cervus elaphus) exposed to increasing levels of human activity. We fitted 184 females with VHF or GPS collars over 4 years and used the Kaplan-Meier survival estimator to calculate annual survival rates. We used multinomial logistic regression to assess differences in cause-specific mortality and generalized linear mixed models to determine how probability of survival was structured during hunting season; both analyses examined a suite of 5 covariates (i. e., age, year, extent of space use, cover, and human footprint) as potentially influencing cause-specific mortality and survival probability. Annual probability of survival averaged 0.8 (±0.02 SE) over 4 years but averaged 0.91 (±0.03 SE) when harvest mortality was excluded, which was the most significant source of mortality in most years (x̃=0.13±0.02 SE). We found no difference between cause-specific mortality sources relative to elk that survived during the hunting season (χ102= 5.79, P = 0.832). The probability of a female surviving during hunting season was negatively influenced by age, year, extent of space use, cover, and human footprint. We found evidence that human activity may have influenced annual rates of natural survival (i. e., exclusive of hunting mortality) and probability of survival during the hunting season. We note that this study occurred largely on privately owned and managed residential and ranch land and focused on female elk; we acknowledge that survival rate and cause-specific patterns of mortality may vary as a function of land ownership (private vs. public), demographic status, and management and harvest practices. While temporal and spatial scales of 1 week may be sufficient to describe patterns of direct mortality during hunting season, broad temporal or spatial scale analyses may be needed to address natural mortality during other seasons. © 2011 The Author(s).

Dzialak M.R.,Hayden Wing Associates LLC | Harju S.M.,Hayden Wing Associates LLC | Osborn R.G.,Hayden Wing Associates LLC | Wondzell J.J.,Hayden Wing Associates LLC | And 3 more authors.
PLoS ONE | Year: 2011

Background: Conserving animal populations in places where human activity is increasing is an ongoing challenge in many parts of the world. We investigated how human activity interacted with maternal status and individual variation in behavior to affect reliability of spatially-explicit models intended to guide conservation of critical ungulate calving resources. We studied Rocky Mountain elk (Cervus elaphus) that occupy a region where 2900 natural gas wells have been drilled. Methodology/Principal Findings: We present novel applications of generalized additive modeling to predict maternal status based on movement, and of random-effects resource selection models to provide population and individual-based inference on the effects of maternal status and human activity. We used a 2×2 factorial design (treatment vs. control) that included elk that were either parturient or non-parturient and in areas either with or without industrial development. Generalized additive models predicted maternal status (parturiency) correctly 93% of the time based on movement. Human activity played a larger role than maternal status in shaping resource use; elk showed strong spatiotemporal patterns of selection or avoidance and marked individual variation in developed areas, but no such pattern in undeveloped areas. This difference had direct consequences for landscape-level conservation planning. When relative probability of use was calculated across the study area, there was disparity throughout 72-88% of the landscape in terms of where conservation intervention should be prioritized depending on whether models were based on behavior in developed areas or undeveloped areas. Model validation showed that models based on behavior in developed areas had poor predictive accuracy, whereas the model based on behavior in undeveloped areas had high predictive accuracy. Conclusions/Significance: By directly testing for differences between developed and undeveloped areas, and by modeling resource selection in a random-effects framework that provided individual-based inference, we conclude that: 1) amplified selection or avoidance behavior and individual variation, as responses to increasing human activity, complicate conservation planning in multiple-use landscapes, and 2) resource selection behavior in places where human activity is predictable or less dynamic may provide a more reliable basis from which to prioritize conservation action. © 2011 Dzialak et al.

Hess J.E.,University of Wyoming | Hess J.E.,Hayden Wing Associates LLC | Beck J.L.,University of Wyoming
Journal of Wildlife Management | Year: 2012

Detecting the disappearance of active leks is the most efficient way to determine large declines in greater sage-grouse (Centrocercus urophasianus) populations; thus, understanding factors that influence lek abandonment is critical. We evaluated factors that may have influenced the probability of sage-grouse lek abandonment in the Bighorn Basin (BHB) of north-central Wyoming from 1980 to 2009. Our objective was to examine lek abandonment based on landscape characteristics that explain differences between occupied and unoccupied leks. We evaluated lek abandonment from 144 occupied and 39 unoccupied leks from the Wyoming Game and Fish Department lek database with sufficient data for our 30-year analysis. We conducted our analysis with binary logistic regression using landscape predictor variables obtained from geographic coverages at 5 scales (1.0-, 3.2-, 4.0-, 5.0-, and 6.4-km radii around leks) to evaluate how these disturbances have influenced lek abandonment. Coverages included anthropogenic characteristics such as agricultural development, oil and gas development, prescribed burned treatments, and roads; and environmental characteristics such as vegetation attributes and wildfire. Our combined model included the number of oil and gas wells in a 1.0-km radius, percent area of wildfire in a 1.0-km radius, and variability in shrub height in a 1.0-km radius around sage-grouse leks. Abandoned (unoccupied) leks had 1.1-times the variability of shrub height in a 1.0-km radius, 3.1-times the percentage of wildfire in a 1.0-km radius, and 10.3-times the number of oil and gas wells in a 1.0-km radius compared to occupied leks. The model-averaged odds of lek persistence with every 1 unit increase in oil and gas wells within a 1.0-km radius was 0.66 (90% CI: 0.37-0.94), odds with every 1% increase in wildfire in a 1.0-km radius was 0.99 (90% CI: 0.85-1.12), and odds with every 1 unit increase in the standard deviation of shrub height within a 1.0-km radius around a lek was 0.77 (90% CI: 0.45-1.08). Because the 90% confidence intervals around the odds ratios of wells did not overlap 1.0, we suggest this predictor variable was most influential in our model-averaged estimates. The BHB has lower developed reserves of oil and gas than many other regions; however, our study supports findings from other studies that demonstrate energy development increases lek abandonment. Our findings indicate conservation efforts should be focused on minimizing well development and implementing wildfire suppression tactics near active sage-grouse leks. © 2012 The Wildlife Society. Copyright © The Wildlife Society, 2012.

Harju S.M.,Hayden Wing Associates LLC | Olson C.V.,Hayden Wing Associates LLC | Dzialak M.R.,Hayden Wing Associates LLC | Mudd J.P.,Hayden Wing Associates LLC | Winstead J.B.,Hayden Wing Associates LLC
PLoS ONE | Year: 2013

Connectivity of animal populations is an increasingly prominent concern in fragmented landscapes, yet existing methodological and conceptual approaches implicitly assume the presence of, or need for, discrete corridors. We tested this assumption by developing a flexible conceptual approach that does not assume, but allows for, the presence of discrete movement corridors. We quantified functional connectivity habitat for greater sage-grouse (Centrocercus urophasianus) across a large landscape in central western North America. We assigned sample locations to a movement state (encamped, traveling and relocating), and used Global Positioning System (GPS) location data and conditional logistic regression to estimate state-specific resource selection functions. Patterns of resource selection during different movement states reflected selection for sagebrush and general avoidance of rough topography and anthropogenic features. Distinct connectivity corridors were not common in the 5,625 km2 study area. Rather, broad areas functioned as generally high or low quality connectivity habitat. A comprehensive map predicting the quality of connectivity habitat across the study area validated well based on a set of GPS locations from independent greater sage-grouse. The functional relationship between greater sage-grouse and the landscape did not always conform to the idea of a discrete corridor. A more flexible consideration of landscape connectivity may improve the efficacy of management actions by aligning those actions with the spatial patterns by which animals interact with the landscape. © 2013 Harju et al.

Harju S.M.,Hayden Wing Associates LLC | Dzialak M.R.,Hayden Wing Associates LLC | Taylor R.C.,Taylor Environmental Consulting LLC | Hayden-Wing L.D.,Hayden Wing Associates LLC | Winstead J.B.,Hayden Wing Associates LLC
Journal of Wildlife Management | Year: 2010

Rapid expansion of energy development in some portions of the Intermountain West, USA, has prompted concern regarding impacts to declining greater sage-grouse (Centrocercus urophasianus) populations. We used retrospective analyses of public data to explicitly investigate potential thresholds in the relationship between lek attendance by male greater sage-grouse, the presence of oil or gas wells near leks (surface occupancy), and landscape-level density of well pads. We used generalized linear models and generalized estimating equations to analyze data on peak male attendance at 704 leks over 12 years in Wyoming, USA. Within this framework we also tested for time-lag effects between development activity and changes in lek attendance. Surface occupancy of oil or gas wells adjacent to leks was negatively associated with male lek attendance in 5 of 7 study areas. For example, leks that had ≥1 oil or gas well within a 0.4-km (0.25-mile) radius encircling the lek had 3591 fewer attending males than leks with no well within this radius. In 2 of these 5 study areas, negative effects of well surface occupancy were present out to 4.8 km, the largest radius we investigated. Declining lek attendance was also associated with a higher landscape-level density of well pads; lek attendance at well-pad densities of 1.54 well pads/km 2 (4 well pads/mile 2) ranged from 13 to 74 lower than attendance at unimpacted leks (leks with zero well pads within 8.5 km). Lek attendance at a well-pad density of 3.09 well pads/km 2 (8 well pads/mile 2) ranged from 77 to 79 lower than attendance at leks with no well pad within 8.5 km. Further, our analysis of time-lag effects suggested that there is a delay of 210 years between activity associated with energy development and its measurable effects on lek attendance. These results offer new information for consideration by land managers on spatial and temporal associations between human activity and lek attendance in sage-grouse, and suggest that regional variation is an important consideration in refining existing management strategies. © The Wildlife Society.

Dzialak M.R.,Hayden Wing Associates LLC | Olson C.V.,Hayden Wing Associates LLC | Harju S.M.,Hayden Wing Associates LLC | Webb S.L.,Hayden Wing Associates LLC | And 3 more authors.
PLoS ONE | Year: 2011

Background: Balancing animal conservation and human use of the landscape is an ongoing scientific and practical challenge throughout the world. We investigated reproductive success in female greater sage-grouse (Centrocercus urophasianus) relative to seasonal patterns of resource selection, with the larger goal of developing a spatially-explicit framework for managing human activity and sage-grouse conservation at the landscape level. Methodology/Principal Findings: We integrated field-observation, Global Positioning Systems telemetry, and statistical modeling to quantify the spatial pattern of occurrence and risk during nesting and brood-rearing. We linked occurrence and risk models to provide spatially-explicit indices of habitat-performance relationships. As part of the analysis, we offer novel biological information on resource selection during egg-laying, incubation, and night. The spatial pattern of occurrence during all reproductive phases was driven largely by selection or avoidance of terrain features and vegetation, with little variation explained by anthropogenic features. Specifically, sage-grouse consistently avoided rough terrain, selected for moderate shrub cover at the patch level (within 90 m 2), and selected for mesic habitat in mid and late brood-rearing phases. In contrast, risk of nest and brood failure was structured by proximity to anthropogenic features including natural gas wells and human-created mesic areas, as well as vegetation features such as shrub cover. Conclusions/Significance: Risk in this and perhaps other human-modified landscapes is a top-down (i.e., human-mediated) process that would most effectively be minimized by developing a better understanding of specific mechanisms (e.g., predator subsidization) driving observed patterns, and using habitat-performance indices such as those developed herein for spatially-explicit guidance of conservation intervention. Working under the hypothesis that industrial activity structures risk by enhancing predator abundance or effectiveness, we offer specific recommendations for maintaining high-performance habitat and reducing low-performance habitat, particularly relative to the nesting phase, by managing key high-risk anthropogenic features such as industrial infrastructure and water developments. © 2011 Dzialak et al.

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