Managing Prairie and Shrubland Grouse Populations in the 21st Century: Revisiting the Declining and Small Population Paradigms

Symposium
ROOM: Room 120 – Dona Ana
SESSION NUMBER: 61
 
Prairie and shrubland grouse have experienced some of the most drastic population declines of any taxonomic group in North America, and several species have or are being considered for listing under the Endangered Species Act. Much of western grasslands and rangelands still support species of prairie chicken, sage-grouse, or sharp-tailed grouse, yet most populations have declined in recent decades. Management efforts to maintain these populations amidst multiple-use resource mandates on public and private land are unlikely to allow for persistence of these species across the landscape. In many cases, research and management are a triage of efforts to understand the persistence of small populations, focused on recovery efforts to address the effects of being small. In some cases, data are available that allow for initial understanding of potential mechanisms causing populations to become small. These are the small and declining population paradigms, and rarely do either of these alone result in the conservation of a species. For conservation of prairie and shrubland grouse to be successful, science and management need to first address what caused the populations to decline, and second, understand what puts small populations at risk of extirpation or extinction. Presentations will highlight recent advances in science to evaluate the success and failure of prairie and shrubland grouse conservation efforts to address the declining and small population paradigms. We will discuss novel approaches that may help to advance grouse conservation by working to sustain small populations while attempting understanding and alleviate some of the external pressures that caused those populations to become small in the first place.

10:30AM Small Populations: Lessons Learned from the Attwater’s Prairie-Chicken
  Michael E. Morrow; John E. Toepfer
Attwater’s prairie-chicken (Tympanuchus cupido attwateri) populations have been in decline since it was described as a subspecies in the late 19th century. Conservation efforts can be characterized as a mix of Caughley’s small- and declining-population paradigms. Early actions were generally consistent with the declining-population paradigm including basic life-history research, protection from hunting, and establishment of protected refuges. Once population declines accelerated in the late 1980’s, recovery philosophy shifted toward principles more aligned with the small-population paradigm. During that time, conservation efforts were motivated by the hypothesis that environmental stochasticity in concert with habitat loss and fragmentation were the primary factors driving population declines. Habitat management was implemented to mitigate potential impacts of environmental variation on any one population, and a captive-rearing program was established to preserve as much genetic information as possible, and to serve as a source stock for population supplementation and repatriation efforts. However, additional research (declining-population paradigm) revealed that the original hypothesis for population decline, while probably correct in the historical context, had been supplanted by an even greater threat. Unsustainably high chick mortality resulting from the indirect effects of red imported fire ants was implicated as the most likely factor limiting recovery efforts. While we appreciate principles of the small-population paradigm in guiding design of conservation reserves, we submit that focused research as prescribed by the declining-population paradigm, not “professional judgement” guided by theory, is essential to successful management of small populations. We disagree with Caughley that the declining-population paradigm lacks theoretical context. Rather, we suggest that Liebig’s Law of the Minimum provides the theoretical framework necessary to guide effective implementation of the declining-population paradigm. While the distinction between these paradigms may seem trivial to some, it is critical for efficient allocation of scarce resources, and may dictate the success of small population rescue efforts.
10:50AM Small Populations of Prairie Grouse; Causes, Consequences, and Challenges
  Michael A. Schroeder
In 1994 Graeme Caughley wrote, “Conservation biology has two threads: the small-population paradigm which deals with the effect of smallness on the persistence of a population, and the declining-population paradigm which deals with the cause of smallness and its cure.” These two issues are currently at the heart of prairie grouse conservation in North America. The prairie grouse species include greater sage-grouse (Centrocercus urophasianus), Gunnison sage-grouse (C. minimus), sharp-tailed grouse (Tympanuchus phasianellus), greater prairie-chicken (T. cupido), and lesser prairie-chicken (T. pallidicintus). All have declined dramatically in the last century. The causes of these population declines have been well documented, including reductions in the quantity, quality, and connectivity of habitat due to various factors such as habitat conversion, tree encroachment, development, and fragmentation. The impacts of these factors result in small isolated areas of occupation, often substantially smaller than the area needed to support a viable population of prairie grouse. We have focused management energy on these small populations, with limited success. The reason for this lack of success appears to be that small populations have inherent issues that cannot be successfully addressed on a limited geographic scale. However, there are now examples where management has ‘scaled-up’ potential solutions to prairie grouse conservation. One example is the Conservation Reserve Program. It is essential that we learn from this example.
11:10AM Comprehensive Habitat Requirements and Migration Strategies of a Small Greater Sage-Grouse Population
  Aaron C. Pratt; Kurt T. Smith; Jeffrey L. Beck
Small, naturally occurring greater sage-grouse (Centrocercus urophasianus) populations are characterized by limited population size capacity, yet provide important conservation value because they often occur in fringe habitat or on the edge of the species range. Thus, conserving small grouse populations may prevent range contractions and maintain genetic connectivity between larger core populations. Because of the unique characteristics of these small populations they may require different approaches to conservation, including approaches to habitat preservation if grouse in small populations use different strategies, such as migration, to meet their annual habitat requirements. This was true for our study population in the Bighorn Basin, which was a small population in naturally-fragmented sagebrush (Artemisia spp.) habitat sandwiched between coniferous forest and saltbush (Atriplex spp.) desert, as compared to our other study population in Central Wyoming, which was a core population within the core of the species range. The Bighorn Basin population had more migrants and migration distances were farther than in Central Wyoming. Our first objective was to compare survival and reproductive success between different migration behavior to determine if there were any benefits. Our second objective was to measure how correlated seasonal (breeding, summer, and winter) and interseasonal habitat was within each contrasting study population. Traditionally, habitat conservation strategies have focused on breeding habitat as priority areas because of its importance for reproductive activities. However, effectively conserving habitat for one season may not capture the habitat needs for a species on an annual basis. Our third objective was to evaluate how well conserving breeding habitat would conserve the comprehensive habitat requirements for grouse within each contrasting study population. Our results are based on study area-specific observations from GPS-equipped female grouse in Central Wyoming (n = 52) and Bighorn Basin (n = 81) from 2011-2015.
11:30AM Landscape Context Is Critical for Conservation of Greater Prairie-Chickens in Nebraska
  Larkin A. Powell; Mary Bomberger Brown; Walter H. Schacht
The greater prairie-chicken (Tympanichus cupido) experienced a contraction in range during European immigrant settlement of the Midwest and Great Plains regions of North America. Populations in Nebraska are robust enough to be managed for annual harvest and have served as donor populations to states where the species was previously extirpated. Biologists are mindful of threats to greater prairie-chickens: loss of grassland habitat, modifications to habitat with rangeland management practices, invasions of grasslands by trees, and energy development. We have a decade of research in Nebraska that can be used to evaluate the differential risk from these potential threats. Our research suggests that there is no one-size-fits-all response that will ensure sustainable populations of prairie-chickens in Nebraska. In southern and eastern Nebraska, the economics of agricultural commodities is the single-most important risk factor for prairie-chickens in the context of farmlands. In the contiguous grassland of the Sandhills region, rangeland management practices are the most critical concern. In many areas in the Sandhills, shelterbelts and invasive eastern red-cedar have most likely affected predator communities as nest, brood, and hen survival are lower than expected in a large-contiguous grassland system. Although wind energy development has increased in recent years, our research suggests that, in this particular landscape, energy development does not pose a local threat to greater prairie-chickens. We identified interesting dynamics related to behavior, predator distribution, and vocalizations near a wind energy facility. But, we did not find negative effects on demographic processes of prairie-chickens. Further, the 15 current wind facilities in Nebraska have a small footprint on the landscape, suggesting that rangeland management and agricultural economics will continue to be the forces that predict success of conservation efforts for greater prairie-chickens in Nebraska.
11:50AM Greater Sage-Grouse Reproductive Habitat Selection, Survival, and Male Lek Counts in Response to Wind Energy Infrastructure
  Chad LeBeau
Increasing concern for environmental sustainability, the demand for domestic energy, and an impetus on reducing dependence on fossil fuels have led to substantial investment in renewable energies including wind energy over the last two decades. Increases in wind energy development are especially noticeable in prairie habitats with high wind capacity. This has raised concerns over impacts to prairie grouse species including greater sage-grouse (Centrocercus urophasianus). We monitored 346 female greater sage-grouse via telemetry from 2009 to 2014 within a control area and an area influenced by a wind energy development to estimate the potential impacts of wind energy infrastructure on greater sage-grouse habitat selection and demography. Our study represents the only situation where habitat selection and demographic responses of sage-grouse to infrastructure associated with a wind energy development has been investigated. We did not detect a negative impact of the wind energy facility on nest site selection or nest survival during the study. The relative probability of greater sage-grouse selecting brood-rearing and summer habitats decreased as percentage of surface disturbance associated with the facility infrastructure increased. However, brood and female survival was not negatively influenced by the facility. The demographic and spatial responses of greater sage-grouse in this study were similar to greater prairie-chickens (Tympanuchus cupido) in response to wind energy development. Future wind energy developments should consider the potential impacts of wind energy development on sage-grouse habitat selection patterns and survival parameters within at least 1.20 km from any occupied sage-grouse nesting, brood-rearing, or summer habitats.
1:10PM Importance of Increased Reproduction in the Success of Sharp-Tailed Grouse Translocations and Efficacy of Artificial Insemination
  Steven R. Mathews; Peter S. Coates; Shwan Espinosa; David J. Delehanty
Prairie and shrubland grouse reproduction centers around leks, which can be viewed as cultural outcomes of grouse social behavior. Lek locations are traditional and likely are learned by young grouse through individual and social experiences. Male grouse exhibit lek philopatry and female grouse exhibit philopatry to nest and brood-rearing areas located near leks. Such cultural information is unavoidably lost under rapid population decline. Translocating grouse places them into areas where they lack cultural information. We carried out a 5-year reintroduction program by translocating Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus) from Idaho to Nevada (> 300 km) and carried out field methods that help to develop cultural and behavioral identity at the restoration site. Our objective was to maximize reproduction rates with the ultimate goal of producing immediate offspring at the release site, such that chicks with no previous experience will develop site fidelity and perhaps make less risky behavioral decisions that would increase population performance. Here, we discuss multiple techniques, including: (1) translocating young female grouse, (2) experimental use of artificial insemination, and (3) timing the capture attempts to target inseminated females and egg-laying females for translocation. We quantified post-release population performance (movement and demography) and generally compared our results with those using more conventional translocation methods. We found that yearling grouse are much better candidates for population restoration than adult grouse and timing the capture of grouse influenced their propensity to nest. We also found demographic information derived from translocated grouse can be misleading because such rates may be substantially different than those from the locally created population (e.g., offspring of translocated grouse), supporting our hypothesis that restoration of cultural affinity to an area improves population recovery.
1:30PM Patterns of Genomic Diversity Loss in Declining Prairie Grouse Populations and Its Implication on Fitness
  Jeff A. Johnson
To what degree genetic processes and their influence on fitness are associated with persistence of populations when of small size is a fundamental question in evolutionary biology and conservation practice in general (i.e., small population paradigm). Nearly neutral theories of genome evolution predict that small population sizes will result in an accumulation of deleterious variation within the genome. Depending on the strength of selection, for example, deleterious recessive traits are more likely maintained within a population of large size due to reduced potential for purging by genetic drift across multiple generations. When significantly reduced in size, however, detrimental traits can increase in frequency due to random processes related to drift. In a previous study investigating the effects of small population size in Attwater’s Prairie-chicken (Tympanuchus cupido attwateri), no significant correlation was observed between survival and genome-wide heterozygosity (22,990 SNPs), yet survival was related to specific alleles at multiple immune genes. Using a recently completed transcriptome of a closely related species, the Greater Prairie-chicken (T. c. pinnatus), I re-evaluate the above dataset to explore whether differences may exist in reference to survival between non-coding and coding sequences. I further explore whether Attwater’s Prairie-chickens possess an excess of detrimental mutations, i.e., amino acid substitutions, stop codons, or deletions compared to Greater Prairie-chickens sampled from large populations. Identifying regions in the genome that are influenced differently by changes in population size would provide a better understanding of the processes important for maintaining long-term self sustainable populations in a human dominated landscape. This work also contributes to identifying the relative importance and joint effects of drift, inbreeding, and local adaptation in captive-release programs and small isolated populations in general.
1:50PM Managing Genetic Diversity in Small Populations of Sage-Grouse: Promise and Pitfalls
  Sara Oyler-McCance
The small population paradigm focuses on the genetic and demographic issues facing populations at risk of extinction due to their small size. For almost two decades genetic data has been collected from populations of both species of sage-grouse (Centrocercus spp) with various goals including defining management units, estimating levels of connectivity, and documenting levels of genetic diversity. Although most sage-grouse populations are relatively well connected, there are several examples of small, isolated populations with lower levels of genetic diversity, particularly in Gunnison Sage-grouse (C. minimus). These small populations are particularly susceptible to genetic drift and potentially inbreeding depression. To make matters worse, the highly skewed mating system of sage-grouse further reduces overall genetic diversity that is passed on to future generations. Management strategies to thwart impacts of low genetic diversity in small populations include reconnecting populations either naturally through restoration of habitat or manually though translocation. Are these management activities particularly helpful in reducing risk of extinction? Or do they do more harm than good? I discuss several examples where management actions have aimed to increase genetic diversity and connectedness among populations with varying levels of success. I also discuss the transition from genetic to genomic data, which allows us to consider adaptive genetic variation when implementing translocation strategies.
2:10PM Lesser Prairie-Chicken Population Dynamics: the Good the Bad and the Ugly
  Christian Hagen
The Lesser Prairie-Chicken (Tympanuchus pallidicinctus; hereafter prairie-chicken) is a species of conservation concern in the United States. The primary threats to prairie-chickens are habitat loss and fragmentation that result from land uses incompatible with the species’ biology. However, landscape scale initiatives are underway and designed to yield population level responses to conservation practices. Further complicating species’ conservation is 90% of its habitat is privately owned. Monitoring biological responses to these conservation actions are paramount to maintain prairie-chicken populations into the future. Because prairie-chicken population dynamics can fluctuate dramatcially such monitor can be a challenge. I will discuss a variety of rangewide population monitoring tools and how they are being used to target conservation efforts and reduce threats facing the species.
2:30PM The Effects of Conifer Encroachment on Greater Sage-Grouse Demography and Tree Removal as a Management Strategy
  John P. Severson; Pete Coates; Mark Ricca; Brian Prochazka; Christian Hagen
Greater sage-grouse (Centrocercus urophasianus) are a sagebrush obligate species that are often considered an indicator of intact sagebrush ecosystems. Conservation of this species can help protect other sagebrush obligate and non-obligate species at large spatial scales, but recent local extirpations and overall widespread population declines indicate problems for sage-grouse and their habitat. Conifer expansion in the sagebrush ecosystem is one important threat to sage-grouse in some areas that can lead to decreased habitat availability and increased fragmentation resulting in small populations and associated reduced demographic performance. Additionally, chronic conifer expansion is a persistent threat that can contribute to continually declining populations and ultimately lead to local extirpation if management action is not implemented. Here, we provide an overview of recent studies linking conifer expansion to sage-grouse demographics including 1) links between avoidance patterns of conifers and impacts on adult survival of sage-grouse, 2) behavioral mechanistic movement patterns that relate to these avoidance and survival patterns, and 3) conifer removal as an effective management action that can improve sage-grouse population vital rates. These studies collectively help explain broader landscape patterns of conifer effects on sage-grouse population persistence, and point to common management goals for conifer removal treatments in sagebrush ecosystems. These accomplished efforts contribute to our ecological understanding as well as to conservation of sage-grouse by reducing negative impacts of small and declining populations on the species.
2:50PM Refreshment Break
3:20PM Potential Restorative Benefits of Tree Removal and Sagebrush Restoration for Gunnison Sage-Grouse
  Jeffrey L. Beck; Kevin E. Doherty; Jacob D. Hennig; Jonathan B. Dinkins; Kathleen A. Griffin; Avery A. Cook; Jeremy D. Maestas; David E. Naugle
Gunnison sage-grouse (Centrocercus minimus) are a federally-threatened shrubland grouse species with a limited range in Colorado and Utah. Gunnison sage-grouse fit both the small and declining population paradigms described by Caughley (1994), compounding conservation challenges. They are a small population species because sagebrush (Artemisia spp.) communities in the Colorado Plateau are naturally fragmented and they are declining due to conifer expansion into sagebrush and additional losses and degradation of habitat attributed to human development and agricultural conversion across historical habitat in Arizona, Colorado, New Mexico, and Utah. Thus, restoring breeding habitat is a top priority. To assess threats on Gunnison sage-grouse lek presence, we developed a spatially-explicit breeding habitat model to compare active lek and random pseudo-absence locations from 2005-2015. Models identified land cover, climatic, and abiotic variables at landscape-level scales (0.56-km and 4-km) most important for predicting breeding habitat. Our model correctly differentiated between lek and pseudo-absence locations 94% of the time. All but one of the active leks (n = 94) were located in areas with >0.65 probability of lek occurrence. Using this probability value as a threshold, we predicted 15% of grouse range as high quality breeding habitat. Simulated removal of trees in areas with ≤30% tree canopy cover (0.56-km scale) increased extent of high quality habitat by 59%. Hypothetical restoration of sagebrush cover in the same areas increased habitat quality an additional 11%. Our breeding habitat model indicated that targeted tree removal and sagebrush restoration may have potential to improve Gunnison sage-grouse breeding habitat. The greatest increase in breeding habitat extent was in western subpopulations of Gunnison sage-grouse, where habitat was most fragmented and conifer encroachment highest. While our habitat treatment scenarios were not meant to be prescriptive, they highlight considerable uplift in Gunnison sage-grouse breeding habitat may be possible across much of its range.
3:40PM Understanding the Broad-Scale Implications of Livestock Management on Sage-Grouse Population Trends Using Public Records
  Adrian P. Monroe; Cameron L. Aldridge; Timothy J. Assal; Kari E. Veblen; David A. Pyke; Michael L. Casazza
Declines in populations of Greater sage-grouse (Centrocercus urophasianus) over the last half-century are well-documented and attributed to a variety of factors including loss of sagebrush (Artemisia spp.) habitat, fire, exotic grasses, and land use. One land use type often implicated in their decline is improper livestock grazing because herbaceous cover is important for sage-grouse nesting and brood rearing. However, sage-grouse require vast landscapes during their life history and there is a lack of studies that directly link population responses of sage-grouse to livestock management at broad scales. The Bureau of Land Management (BLM) currently oversees livestock grazing on nearly 61 million ha of rangeland across the Western United States, and their records may provide a unique opportunity to assess sage-grouse responses to livestock management. We used grazing data collected annually by BLM from 1,096 grazing allotments in Wyoming, USA, and then used annual counts of displaying males from 743 lek sites (2004-2014) to evaluate sage-grouse population trends in response to the timing and level of grazing, and interactions with local vegetation productivity. We found that livestock records corresponded with both positive and negative trends among sage-grouse populations depending on the timing and level of grazing, although these relationships may vary local vegetation productivity. Our findings suggest a benefit of broad-scale analyses when evaluating effects of livestock management by revealing patterns not readily apparent from more fine-scale studies, which could provide new insights into this ubiquitous land use across the sage-grouse range.
4:00PM The Adverse Impacts of Wildfire to Greater Sage-Grouse Population Numbers in the Great Basin: Inferences for Management Actions
  Mark A. Ricca; Peter S. Coates; Brian G. Prochazka; Matthew L. Brooks; Kevin E. Doherty; Erik J. Blomberg; Christian A. Hagen; Cameron L. Aldridge; Steven Hanser; David A. Pyke; Michael L. Casazza
Iconic sagebrush ecosystems of the American West are threatened by accelerated wildfires that can kill sagebrush and facilitate invasion by flammable annual grasses. The result is a non-analog positive feedback loop that consumes large expanses of sagebrush that often do not recover, yet how this feedback may drive population declines of obligate sagebrush species, such as greater sage-grouse (hereafter, sage-grouse), have not been quantified rigorously over large spatiotemporal scales. Within a Bayesian framework, we analyzed 30 years of wildfire and climatic effects on population growth rates of sage-grouse across the Great Basin, and accounted for variation in sagebrush recovery time after fire as determined by underlying soil properties that influence ecosystem resilience to disturbance and resistance to invasion. The cumulative loss of sagebrush to direct and indirect effects of wildfire has contributed strongly to declining populations of sage-grouse over the last 30 years. Most importantly, long-lasting effects from wildfire nullified pulses of sage-grouse population growth that typically follow years of high precipitation. If wildfire trends continue unabated, model-projections indicate populations will be reduced to 43% of their current numbers over the next 3 decades. Now that a strong mechanism driving population declines has been identified, we present scenario-based simulations to inform targeted fire suppression efforts, as well data-driven decision support tools to inform post-fire restoration actions, that may stabilize sage-grouse populations and prevent entry into Caughley’s small-population paradigm.
4:20PM Simulating the Causes and Fates of Small and Declining Sage-Grouse Populations Using Spatially Explicit Individual-Based Modeling Approaches
  Julie A. Heinrichs; Cameron L. Aldridge
Effective conservation research and action requires addressing both the causes of population decline and the implications of small population sizes. Ecological research is increasingly evaluating the causes of decline, but the integration of small and declining population paradigms lags behind. Field experiments and data collection, historical reconstructions, and statistical evaluations are building evidence to support the causes of decline and persistence implications of small populations. However, few approaches explicitly link the mechanisms of decline with population consequences to inform conservation actions. Spatially explicit individual-based models are uniquely suited to combine the ideas and analyses from single paradigms to address questions that are relevant to small, declining populations. By linking habitat and system changes with individual responses, the contributions of each cause of decline to population size and persistence can be compared. Simulation approaches further provide the means for subtle and incremental shifts in habitat conditions, movement, habitat selection, behavior, or demography to accumulate through time and impact populations, informing the population-level consequences of ‘declining’ to a smaller population. We provide examples of decision support models to inform the management of small and/or declining Greater Sage-grouse populations in Canada and Wyoming, USA. We used spatially explicit simulation approaches in Wyoming to compare potential future declines caused by climate-induced habitat changes and an increasing oil and gas development footprint, associated Sage-grouse avoidance behavior, and reduced demography. Results indicated that population responses to development that could outweigh climate-induced changes in habitat within Wyoming, and potentially isolate local populations within protected core areas. Simulation models used in Canadian populations indicated sensitivities of the small populations to low survival rates, and strong source-sink dynamics. Spatially targeting habitat restoration by source-sink condition improved short-term population gains; however, multiple actions addressing both small and declining population factors are required to stabilize the population.
4:40PM A Data-Driven Decision Point Tool to Signal Sage-Grouse Population Declines at Multiple Spatial Scales for Adaptive Management
  Peter S. Coates; Mark A. Ricca; Brian G. Prochazka; Cameron L. Aldridge; Steve E. Hanser; Kevin E. Doherty
Population ecologists have recognized increasingly the importance of ecological scale in understanding processes that guide observed demographic patterns for prairie and shrubland grouse species. However, directly incorporating spatial scale into monitoring strategies that ‘flag’ declining populations before they reach critical low numbers are challenging and rarely implemented. Identifying such populations and appropriate spatial scale is critical so that management actions designed to reverse those trends are applied effectively. We describe a novel example of a hierarchical monitoring framework to estimate annual rates of population change (λ) for greater sage-grouse (Centrocercus urophasianus) across multiple biologically relevant spatial scales. Specifically, we used a 17-year lek count dataset in the Great Basin to estimate λ and compared trends across nested spatial scales using a Bayesian hierarchical modeling approach. This framework allowed us to flag declining populations across multiple spatial scales based on two criteria: declining λ and a decoupling of λ from larger scales. We offer a range of values for these criteria derived from modeled simulations. This approach can be carried out on an annual basis to identify declining populations before they are threatened with local extirpation. Furthermore, biotic and abiotic effects on λ can be partitioned across different spatial scales. For example, declines governed by local disturbances are disentangled from those that operate at larger spatial scales (e.g., broad-scale wildfire and region-wide drought). Overall, this framework could facilitates effective and responsive management actions for grouse populations annually provided lek count data, and similar hierarchical approaches might be beneficial for other species occupying landscapes with heterogeneous disturbance and climatic regimes.

 
Organizers: Cameron Aldridge, Colorado State University, Fort Collins, CO; Jeffrey Beck, University of Wyoming, Laramie, WY; Clait Braun , Grouse Inc., Tucson, AZ; Steve Hanser, U.S. Geological Survey, Reston, VA; Peter Coates, U.S. Geological Survey, Dixon, CA
 

Symposium
Location: Albuquerque Convention Center Date: September 26, 2017 Time: 10:30 am - 5:00 pm