Matthew R. Dzialak

Identifying and Prioritizing Greater Sage-Grouse Nesting and Brood-Rearing Habitat for Conservation in Human-Modified Landscapes

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 m2), 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.

Landscape features and weather influence nest survival of a ground-nesting bird of conservation concern, the greater sage-grouse, in human- altered environments

IntroductionGround-nesting birds experience high levels of nest predation. However, birds can make selection decisions related to nest site location and characteristics that may result in physical, visual, and olfactory impediments to predators.MethodsWe studied daily survival rate [DSR] of greater sage-grouse (Centrocercus urophasianus) from 2008 to 2010 in an area in Wyoming experiencing large-scale alterations to the landscape. We used generalized linear mixed models to model fixed and random effects, and a correlation within nesting attempts, individual birds, and years.ResultsPredation of the nest was the most common source of nest failure (84.7%) followed by direct predation of the female (13.6%). Generally, landscape variables at the nest site (≤ 30 m) were more influential on DSR of nests than features at larger spatial scales. Percentage of shrub canopy cover at the nest site (15-m scale) and distances to natural gas wells and mesic areas had a positive relationship with DSR of nests, whereas distance to roads had a negative relationship with DSR of nests. When added to the vegetation model, maximum wind speed on the day of nest failure and a 1-day lag in precipitation (i.e., precipitation the day before failure) improved model fit whereby both variables negatively influenced DSR of nests.ConclusionsNest site characteristics that reduce visibility (i.e., shrub canopy cover) have the potential to reduce depredation, whereas anthropogenic (i.e., distance to wells) and mesic landscape features appear to facilitate depredation. Last, predators may be more efficient at locating nests under certain weather conditions (i.e., high winds and moisture).

Prioritizing Conservation of Ungulate Calving Resources in Multiple-Use Landscapes

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.

The spatial pattern of demographic performance as a component of sustainable landscape management and planning

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.

Temporal and hierarchical spatial components of animal occurrence: conserving seasonal habitat for greater sage‐grouse

Developing strategies for sustainable management of landscapes requires research that bridges regionally important ecological and socioeconomic issues, and that aims to provide solutions to sustainability problems. We integrated Global Positioning Systems (GPS) telemetry and statistical modeling to quantify hierarchical spatial and temporal components of occurrence among greater sage-grouse (Centrocercus urophasianus; n = 87), a species of conservation concern, with the larger goal of developing spatially-explicit guidance for conservation of important winter habitat in a Wyoming, USA landscape undergoing development for energy resources. The pattern of occurrence at the landscape level (second-order) and within seasonal use areas (third-order) included selection for shrub vegetation with a prominent sagebrush (Artemisia spp.) component, and avoidance of rough terrain, mesic areas, and human activity. A change in resource selection behavior across the diel cycle was not an apparent component of the higher-order selection process; however, at the finer scale of investigation sage-grouse shifted behavior across the diel cycle in ways likely related to risk aversion or maintaining a favorable thermal environment (i.e., day-time-only avoidance of natural gas wells and night-time-only selection for taller shrubs). At both spatial scales there was considerably more variation among individuals in the sign of their association with anthropogenic features than with vegetation and terrain. The final spatially-explicit model, which depicted lower-order selection (local, patch-level, and seasonal use area) across the diel cycle constrained by selection processes at a higher order (second-order), validated well, offering specific guidance for managing human activity and sage-grouse conservation in the study area, and general guidance in developing sustainable landscape management strategies when animal occurrence reflects multiple spatial and temporal processes.

Corridors affect dispersal initiation in reintroduced peregrine falcons

We reintroduced 33 peregrine falcons (Falco peregrinus) at two release areas with contrasting habitat configurations to assess landscape influences on dispersal. One site (Daniel Boone National Forest) had non-forested corridors within a forest matrix, whereas the other site (Tom Dorman State Nature Preserve) had forested corridors within an agricultural matrix. We used aerial telemetry and ground observation to assess differences in dispersal between sites and we used multivariate statistical analyses to detect combinations of response variables depicting landscape influences. Non-forested corridors at Daniel Boone affected post-fledging movements and initiation of dispersal, whereas no discernable pattern in dispersal initiation was observed at Dorman Preserve. Results included significant (p<0.05) differences between peregrines at Daniel Boone and Dorman Preserve in x± SD post-fledging area (PFA) size (2643.5±2599.0 and 931.7±732.1 ha, respectively), maximum movement distances (12.9±13.9 and 6.1±4.6 km, respectively), orientation of movements (second-order x angle±95% confidence interval (CI)=280.8±58.6 (non-random orientation) and 358.8±98.8 (random orientation), respectively), time spent on the PFA (16.0±12.2 and 31.0±3.3 days, respectively) and selection of agricultural habitats (Euclidean distance vectors ρ=0.66 and ρ=2.50, respectively). Selection of agriculture by peregrines released on Daniel Boone reflected selection of corridors as part of pre-dispersal movement. These results, coupled with generally unorientated movement behaviour by Dorman Preserve peregrines, provided evidence for an influence of functional landscape connectivity on dispersal in peregrines.

Greater Sage-Grouse and Severe Winter Conditions: Identifying Habitat for Conservation

Abstract Developing sustainable rangeland management strategies requires solution-driven research that addresses ecological issues within the context of regionally important socioeconomic concerns. A key sustainability issue in many regions of the world is conserving habitat that buffers animal populations from climatic variability, including seasonal deviation from long-term precipitation or temperature averages, and that can establish an ecological bottleneck by which the landscape-level availability of critical resources becomes limited. We integrated methods to collect landscape-level animal occurrence data during severe winter conditions with estimation and validation of a resource selection function, with the larger goal of developing spatially explicit guidance for rangeland habitat conservation. The investigation involved greater sage-grouse (Centrocercus urophasianus) that occupy a landscape that is undergoing human modification for development of energy resources. We refined spatial predictions by exploring how reductions in the availability of sagebrush (as a consequence of increasing snow depth) may affect patterns of predicted occurrence. Occurrence of sage-grouse reflected landscape-level selection for big sagebrush, taller shrubs, and favorable thermal conditions and avoidance of bare ground and anthropogenic features. Refinement of spatial predictions showed that important severe winter habitat was distributed patchily and was constrained in spatial extent (7–18% of the landscape). The mapping tools we developed offer spatially explicit guidance for planning human activity in ways that are compatible with sustaining habitat that functions disproportionately in population persistence relative to its spatial extent or frequency of use. Increasingly, place-based, quantitative investigations that aim to develop solutions to landscape sustainability issues will be needed to keep pace with human-modification of rangeland and uncertainty associated with global climate change and its effects on animal populations.

An Assessment of Raptor Hacking During a Reintroduction

Abstract As part of a program to recover the peregrine falcon (Falco peregrinus) in the southeastern United States, we assessed procedural and demographic influences on hacking success by evaluating inherent variation and incorporating controlled manipulation in hacking protocol. We examined release age and date, release cohort size and sex ratio, postfledging area occupancy, and feeding regimen. Fourteen peregrines dispersed successfully, 9 dispersed prematurely, and 5 died before dispersal. Generally, these variables were poor predictors of success with release age (t = −1.29, P = 0.25) and feeding regimen (χ2 = 1.32, P = 0.25) showing only weak associations with success. Sex interacted predictably with release age and postfledging area occupancy to influence success; males were more successful when released younger (± SD days = 45.4 ± 2.8 [successful] and 47.1 ± 5.0 [unsuccessful]) onto a postfledging area occupied by few conspecifics (± SD number of peregrines = 0.3 ± 0.4 [successful] and 1.3 ± 1.3 [unsuccessful]), whereas females were more successful when released older (47.0 ± 1.8 [successful] and 44.5 ± 0.7 [unsuccessful]) and were unaffected by postfledging area occupancy (0.9 ± 0.8 [successful] and 1.0 ± 1.4 [unsuccessful]). These results added substantiation to the perception of hacking as a procedurally sound tool in the release of captive-reared peregrines and highlighted some alternate considerations on feeding regimen and release-cohort sex ratio in raptor hacking.

A flexible approach for assessing functional landscape connectivity, with application to greater sage-grouse (Centrocercus urophasianus).

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.

Incorporating within- and between-patch resource selection in identification of critical habitat for brood-rearing greater sage-grouse

IntroductionIncorporating information on animal behavior in resource-based predictive modeling (e.g., occurrence mapping) can elucidate the relationship between process and spatial pattern and depict habitat in terms of its structure as well as its function. In this paper, we assigned location data on brood-rearing greater sage-grouse (Centrocercus urophasianus) to either within-patch (encamped) or between-patch (traveling) behavioral modes by estimating a movement-based relative displacement index. Objectives were to estimate and validate spatially explicit models of within- versus between-patch resource selection for application in habitat management and compare these models to a non-behaviorally adjusted model.ResultsA single model, the vegetation and water resources model, was most plausible for both the encamped and traveling modes, including the non-behaviorally adjusted model. When encamped, sage-grouse selected for taller shrubs, avoided bare ground, and were closer to mesic areas. Traveling sage-grouse selected for greater litter cover and herbaceous vegetation. Preference for proximity to mesic areas was common to both encamped and traveling modes and to the non-behaviorally adjusted model. The non-behaviorally adjusted map was similar to the encamped model and validated well. However, we observed different selection patterns during traveling that could have been masked had behavioral state not been accounted for.ConclusionsCharacterizing habitat that structured between-patch movement broadens our understanding of the habitat needs of brood-rearing sage-grouse, and the combined raster surface offers a reliable habitat management tool that is readily amenable to application by GIS users in efforts to focus sustainable landscape management.