Lesser prairie-chicken dispersal after translocation: Implications for restoration and population connectivity

Conservation translocations are frequently inhibited by extensive dispersal after release, which can expose animals to dispersal-related mortality or Allee effects due to a lack of nearby conspecifics. However, translocation-induced dispersals also provide opportunities to study how animals move across a novel landscape, and how their movements are influenced by landscape configuration and anthropogenic features. Translocation among populations is considered a potential conservation strategy for lesser prairie-chickens (Tympanuchus pallidicinctus). We determined the influence of release area on dispersal frequency by translocated lesser prairie-chickens and measured how lesser prairie-chickens move through grassland landscapes through avoidance of anthropogenic features during their dispersal movements. We translocated 411 lesser prairie-chickens from northwest Kansas to southeastern Colorado and southwestern Kansas in 2016-2019. We used satellite GPS transmitters to track 115 lesser prairie-chickens throughout their post-release dispersal movements. We found that almost all lesser prairie-chickens that survived from their spring release date until June undergo post-translocation dispersal, and there was little variation in dispersal frequency by release area (96% of all tracked birds, 100% in Baca County, Colorado, 94% in Morton County, Kansas, n = 55). Dispersal movements (male: 103 ± 73 km, female: 175 ± 108 km, n = 62) led to diffusion across landscapes, with 69% of birds settling >5 km from their release site. During dispersal movements, translocated lesser prairie-chickens usually travel by a single 3.75 ± 4.95 km dispersal flight per day, selecting for steps that end far from roads and in Conservation Reserve Program (CRP) grasslands. Due to this "stepping stone" method of transit, landscape connectivity is optimized when <5 km separates grassland patches on the landscape. Future persistence of lesser prairie-chicken populations can be aided through conservation of habitat and strategic placement of CRP to maximize habitat connectivity. Dispersal rates suggest that translocation is better suited to objectives for regional, rather than site-specific, population augmentation for this species.

Understanding behavioral intention of landowners to promote wildlife richness and biodiversity in the Southern Great Plains

Ranchers have been conducting traditional management practices such as mono-species grazing and limited burning that focus on stocking rate maximization. This has resulted in negative environmental consequences such as woody plant encroachment, land use change, and species diversity loss. Recently, there has been a growing appreciation for alternative range management that simultaneously promotes biodiversity and agricultural productivity through fire and grazing interactions. The purpose of the study was to investigate the influence of landowner values, attitudes, and norms on their behavioral intention to adopt best management practices (BMPs) that enhance wildlife abundance in the southern Great Plains. The required data was generated through a mail survey following the Tailored Design method. We utilized the structural equation path model to construct two latent variables for norms and attitudes and analyzed the relationship of the latent variables with value orientations and behavioral intentions. The study results indicated that the attitudes had a significant positive relationship with biocentric (β = 0.15, p-value<0.05) and a negative relationship with anthropocentric (β = -0.259, p-value<0.05) value orientations, however, the relationship of value orientations was statistically insignificant with norms. Further, the results indicated that both norms (β = 0.404, p-value<0.05) and attitudes (β = 0.508, p-value<0.05) had a positive and statistically significant relation with ranchers' intentions to increase wildlife abundance on their land. Study results emphasize the need for innovative communication and non-traditional outreach methods to educate rangeland owners on the importance of patch-burn grazing and other best management practices.

Variation among arthropod taxa in the amino acid content of exoskeleton and digestible tissue

Arthropod consumption provides amino acids to invertebrates and vertebrates alike, but not all amino acids in arthropods may be digestible as some are bound in the exoskeleton. Consumers may not be able to digest exoskeleton in significant amounts or avoid it entirely (e.g., extraoral digestion). Hence, measures that do not separate digestible amino acids from those in exoskeleton may not accurately represent the amino acids available to consumers. Additionally, arthropods are taxonomically diverse, and it remains unclear if taxonomic differences also reflect differences in amino acid availability. Thus, we tested: (1) if there were consistent differences in the content and balance of amino acids between the digestible tissue and exoskeleton of arthropods and (2) if arthropod Orders differ in amino acid content and balance. We measured the amino acid content (mg/100 mg dry mass) and balance (mg/100 mg protein) of whole bodies and exoskeleton of a variety of arthropods using acid hydrolysis. Overall, there was higher amino acid content in digestible tissue. There were also significant differences in the amino acid balance of proteins in digestible tissue and exoskeleton. Amino acid content and balance also varied among Orders; digestible tissues of Hemiptera contained more of some essential amino acids than other Orders. These results demonstrate that arthropod taxa vary in amino acid content, which could have implications for prey choice by insectivores. In addition, exoskeleton and digestible tissue content differ in arthropods, which means that whole body amino acid content of an arthropod is not necessarily a predictor of amino acid intake of a predator that feeds on that arthropod.

Review of range-wide vital rates quantifies eastern wild Turkey population trajectory

Recent declines in eastern wild turkeys (Meleagris gallopavo silvestris) have prompted increased interest in management and research of this important game species. However, the mechanisms underlying these declines are unclear, leaving uncertainty in how best to manage this species. Foundational to effective management of wildlife species is understanding the biotic and abiotic factors that influence demographic parameters and the contribution of vital rates to population growth. Our objectives for this study were to (1) conduct a literature review to collect all published vital rates for eastern wild turkey over the last 50 years, (2) perform a scoping review of the biotic and abiotic factors that have been studied relative to wild turkey vital rates and highlight areas that require additional research, and (3) use the published vital rates to populate a life-stage simulation analysis (LSA) and identify the vital rates that make the greatest contribution to population growth. Based on published vital rates for eastern wild turkey, we estimated a mean asymptotic population growth rate (λ) of 0.91 (95% CI = 0.71, 1.12). Vital rates associated with after-second-year (ASY) females were most influential in determining population growth. Survival of ASY females had the greatest elasticity (0.53), while reproduction of ASY females had lower elasticity (0.21), but high process variance, causing it to explain a greater proportion of variance in λ. Our scoping review found that most research has focused on the effects of habitat characteristics at nest sites and the direct effects of harvest on adult survival, while research on topics such as disease, weather, predators, or anthropogenic activity on vital rates has received less attention. We recommend that future research take a more mechanistic approach to understanding variation in wild turkey vital rates as this will assist managers in determining the most appropriate management approach.

Bison movements change with weather: Implications for their continued conservation in the Anthropocene

Animal movement patterns are affected by complex interactions between biotic and abiotic landscape conditions, and these patterns are being altered by weather variability associated with a changing climate. Some animals, like the American plains bison (Bison bison L.; hereafter, plains bison), are considered keystone species, thus their response to weather variability may alter ecosystem structure and biodiversity patterns. Many movement studies of plains bison and other ungulates have focused on point-pattern analyses (e.g., resource-selection) that have provided information about where these animals move, but information about when or why these animals move is limited. For example, information surrounding the influence of weather on plains bison movement in response to weather is limited but has important implications for their conservation in a changing climate. To explore how movement distance is affected by weather patterns and drought, we utilized 12-min GPS data from two of the largest plains bison herds in North America to model their response to weather and drought parameters using generalized additive mixed models. Distance moved was best predicted by air temperature, wind speed, and rainfall. However, air temperature best explained the variation in distance moved compared to any other single parameter we measured, predicting a 48% decrease in movement rates above 28°C. Moreover, severe drought (as indicated by 25-cm depth soil moisture) better predicted movement distance than moderate drought. The strong influence of weather and drought on plains bison movements observed in our study suggest that shifting climate and weather will likely affect plains bison movement patterns, further complicating conservation efforts for this wide-ranging keystone species. Moreover, changes in plains bison movement patterns may have cascading effects for grassland ecosystem structure, function, and biodiversity. Plains bison and grassland conservation efforts need to be proactive and adaptive when considering the implications of a changing climate on bison movement patterns.

Factors influencing the persistence of a fire-sensitive Artemisia species in a fire-dependent ecosystem

Fire refugia and patchiness are important to the persistence of fire-sensitive species and may facilitate biodiversity conservation in fire-dependent landscapes. Playing the role of ecosystem engineers, large herbivores alter vegetation structure and can reduce wildfire risk. However, herbivore effects on the spatial variability of fire and the persistence of fire-sensitive species are not clear. To examine the hypothesis that large herbivores support the persistence of fire-sensitive species through the creation of fire refugia in fire-prone landscapes, we examined the response of a fire-sensitive plant, Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis [Beetle & Young]) to fire and grazing in the fire-dependent mixed-grass prairie of the northern Great Plains. We carried out a controlled burn in 2010 within pre-established exclosures that allowed differential access to wild and domestic herbivores and no record of fire in the previous 75 years due to fire suppression efforts. The experiment was set up with a split-plot design to also examine potential changes in plots that were not burned. Canopy cover of big sagebrush was recorded before the burn in 2010 and again in 2011 with percent area burned recorded within 1-month post-fire in the burned plots. Percentage area burned was the greatest in ungulate exclosures (92% ± 2%) and the least in open areas (55% ± 21%), suggesting that large herbivores influenced fire behavior (e.g., reducing fire intensity and rate of spread) and are likely to increase fire patchiness through their alterations to the fuel bed. Regression analysis indicated that the proportion of sagebrush cover lost was significantly correlated with the proportion of area burned (R²  = 0.76, p = 0.05). No differences in the non-burn plots were observed among grazing treatments or among years. Altogether, this illustrates the potential importance of large herbivores in creating biotic-driven fire refugia for fire-sensitive species to survive within the flammable fuel matrix of fire-dependent grassland ecosystems such as the mixed-grass prairie. Our findings also attest to the resiliency of the northern Great Plains to fire and herbivory and underscore the value of managing grasslands for heterogeneity with spatial and temporal variations in these historic disturbances.

Climate alters the movement ecology of a non-migratory bird

Global climate change is causing increased climate extremes threatening biodiversity and altering ecosystems. Climate is comprised of many variables including air temperature, barometric pressure, solar radiation, wind, relative humidity, and precipitation that interact with each other. As movement connects various aspects of an animal's life, understanding how climate influences movement at a fine-temporal scale will be critical to the long-term conservation of species impacted by climate change. The sedentary nature of non-migratory species could increase some species risk of extirpation caused by climate change. We used Northern Bobwhite (Colinus virginianus; hereafter bobwhite) as a model to better understand the relationship between climate and the movement ecology of a non-migratory species at a fine-temporal scale. We collected movement data on bobwhite from across western Oklahoma during 2019-2020 and paired these data with meteorological data. We analyzed movement in three different ways (probability of movement, hourly distance moved, and sinuosity) using two calculated movement metrics: hourly movement (displacement between two consecutive fixes an hour apart) and sinuosity (a form of tortuosity that determines the amount of curvature of a random search path). We used generalized linear-mixed models to analyze probability of movement and hourly distance moved, and used linear-mixed models to analyze sinuosity. The interaction between air temperature and solar radiation affected probability of movement and hourly distance moved. Bobwhite movement increased as air temperature increased beyond 10°C during low solar radiation. During medium and high solar radiation, bobwhite moved farther as air temperature increased until 25-30°C when hourly distance moved plateaued. Bobwhite sinuosity increased as solar radiation increased. Our results show that specific climate variables alter the fine-scale movement of a non-migratory species. Understanding the link between climate and movement is important to determining how climate change may impact a species' space use and fitness now and in the future.

Why did the chicken not cross the road? Anthropogenic development influences the movement of a grassland bird

Movement and selection are inherently linked behaviors that form the foundation of a species' space-use patterns. Anthropogenic development in natural ecosystems can result in a variety of behavioral responses that can involve changes in either movement (speed or direction of travel) or selection (resources used), which in turn may cause population-level consequences including loss of landscape connectivity. Understanding how a species alters these different behaviors in response to human activity is essential for effective conservation. In this study, we investigated the effects of anthropogenic development such as roads, power lines and oil wells on the greater prairie-chicken (Tympanuchus cupido) movement and selection behaviors in the post-nesting and non-breeding season. Our first objective was to assess using integrated step selection analysis (iSSA) if greater prairie-chickens altered their movement behaviors or their selection patterns when encountering oil wells, power lines, or roads. Our second objective was to determine whether prairie-chickens avoided crossing linear features such as roads or power lines by comparing the number of crossing events in greater prairie-chicken movement tracks to the number of movements that crossed these features in simulated movement tracks. Based on the iSSA analysis, we found that greater prairie-chickens avoided oil wells, power lines, and roads in both seasons, and altered their rate of movement when near anthropogenic structures. However, changes in speed varied by season, with prairie-chickens increasing their movement rates in the post-nesting season when near to development and decreasing movement rates in the non-breeding season. Furthermore, prairie-chickens crossed roads and power lines at much lower rates than expected. These changes in behavior can result in habitat loss for greater prairie-chickens, as well as the potential loss of landscape connectivity. By considering both movement and selection, we were able to develop an ecological understanding of how increasing human activity may influence the space use of this species of conservation concern. Furthermore, this research provides insight into the decision-making processes by animals when they encounter anthropogenic development.

Fire management alters the thermal landscape and provides multi-scale thermal options for a terrestrial turtle facing a changing climate

As effects of climate change intensify, there is a growing need to understand the thermal properties of landscapes and their influence on wildlife. A key thermal property of landscapes is vegetation structure and composition. Management approaches can alter vegetation and consequently the thermal landscape, potentially resulting in underappreciated consequences for wildlife thermoregulation. Consideration of spatial scale can clarify how management overlaid onto existing vegetation patterns affects thermal properties of landscapes relevant to wildlife. We examined effects of temperature, fire management, and vegetation structure on multi-scale habitat selection of an ectothermic vertebrate (the turtle Terrapene carolina triunguis) in the Great Plains of the central United States by linking time-since-fire data from 18 experimental burn plots to turtle telemetry locations and thermal and vegetation height data. Within three 60-ha experimental landscapes, each containing six 10-ha sub-blocks that are periodically burned, we found that turtles select time-since-fire gradients differently depending on maximum daily ambient temperature. At moderate temperatures, turtles selected sub-blocks with recent (<1 year) time-since-fire, but during relatively hot and cool conditions, they selected sub-blocks with later (2-3 year) time-since-fire that provided thermal buffering compared with recently burned sub-blocks. Within 10-ha sub-blocks, turtles selected locations with taller vegetation during warmer conditions that provided thermal buffering. Thermal performance curves revealed that turtle activity declined as temperatures exceeded ~24-29°C, and on "heat days" (≥29°C) 73% of turtles were inactive compared with 37% on non-heat days, emphasizing that thermal extremes may lead to opportunity costs (i.e., foregone benefits turtles could otherwise accrue if active). Our results indicate that management approaches that promote a mosaic of vegetation heights, like spatiotemporally dynamic fire, can provide thermal refuges at multiple spatial scales and thus be an actionable way to provide wildlife with multiple thermal options in the context of ongoing and future climate change.

Arthropod prey vary among orders in their nutrient and exoskeleton content

Insectivores gain macronutrients and elements from consuming arthropod prey, but must also deal with indigestible components (i.e., exoskeleton) of prey. For example, avian chicks (e.g., northern bobwhites; Colinus virginianus) have limited gut space, and ingesting prey with relatively higher proportions of indigestible components may impact assimilation efficiency, growth, and survival. The ability of insectivores to choose higher quality prey would depend on prey taxa varying consistently in nutritional content. We tested whether there were consistent differences among taxonomic orders of arthropod prey in their macronutrient (protein and lipid), elemental (C and N), and exoskeleton content. We used northern bobwhite chicks as our focal insectivore and focused on their potential prey as a case study. We also tested the influence of indigestible exoskeleton on the measurement of macronutrient content and the ability of elemental content to predict macronutrients. We found large and consistent variation in macronutrient and elemental content between arthropod orders. Some orders had consistently high protein content and low exoskeleton content (i.e., Araneae) and are likely higher quality prey for insectivores. Abundant orders common in the diets of insectivores, like Hymenoptera and Coleoptera, had high exoskeleton content and low protein content. We also found support for the ability of elements to predict macronutrients and found that metabolizable (i.e., exoskeleton removed) elemental content better predicted macronutrient content. A better understanding of arthropod nutrient content is critical for elucidating the role of spatial and temporal variation in prey communities in shaping the growth and survival of insectivores.

Woody encroachment of grasslands: Near-surface thermal implications assessed through the lens of an astronomical event

Temperature has long been understood as a fundamental condition that influences ecological patterns and processes. Heterogeneity in landscapes that is structured by ultimate (climate) and proximate (vegetation, topography, disturbance events, and land use) forces serve to shape thermal patterns across multiple spatio-temporal scales. Thermal landscapes of grasslands are likely shifting as woody encroachment fragments these ecosystems and studies quantifying thermal fragmentation in grassland systems resulting from woody encroachment are lacking. We utilized the August 21st, 2017, solar eclipse to mimic a rapid sunrise/sunset event across a landscape characterized as a grassland to experimentally manipulate levels of solar radiation in the system. We then quantified changes in near-surface temperatures resulting from changes in solar radiation levels during the eclipse. Temperatures were monitored across three grassland pastures in central Oklahoma that were characterized by different densities (low, medium, and high) of Juniperus virginiana to understand the impact of woody encroachment on diurnal temperature patterns and thermal heterogeneity in a grassland's thermal landscape. The largest temperature range across sites that occurred during the eclipse was in the mixed grass vegetation. Similarly, the largest change in thermal heterogeneity occurred in the grassland with the lowest amount of woody encroachment. Thermal heterogeneity was lowest in the highly encroached grassland, which also experienced the lowest overall change in thermal heterogeneity during the eclipse. Time series models suggested that solar radiation was the most influential factor in predicting changes in thermal heterogeneity as opposed to ambient temperature alone. These results suggest that highly encroached grasslands may experience lower diurnal variability of temperatures at the cost of a decrease in the overall thermal heterogeneity of that landscape. It appears that fine-scale spatio-temporal thermal variation is largely driven by solar radiation, which can be influenced by vegetation heterogeneity inherent within a landscape.

Generalist bird exhibits site-dependent resource selection

Quantifying resource selection (an organism's disproportionate use of available resources) is essential to infer habitat requirements of a species, develop management recommendations, predict species responses to changing conditions, and improve our understanding of the processes that underlie ecological patterns. Because study sites, even within the same region, can differ in both the amount and the arrangement of cover types, our objective was to determine whether proximal sites can yield markedly different resource selection results for a generalist bird, northern bobwhite (Colinus virginianus). We used 5 years of telemetry locations and newly developed land cover data at two, geographically distinct but relatively close sites in the south-central semi-arid prairies of North America. We fit a series of generalized linear mixed models and used an information-theoretic model comparison approach to identify and compare resource selection patterns at each site. We determined that the importance of different cover types to northern bobwhite is site-dependent on relatively similar and nearby sites. Specifically, whether bobwhite selected for shrub cover and whether they strongly avoided trees, depended on the study site in focus. Additionally, the spatial scale of selection was nearly an order of magnitude different between the cover types. Our study demonstrates that-even for one of the most intensively studied species in the world-we may oversimplify resource selection by using a single study site approach. Managing the trade-offs between practical, generalized conclusions and precise but complex conclusions is one of the central challenges in applied ecology. However, we caution against setting recommendations for broad extents based on information gathered at small extents, even for a generalist species at adjacent sites. Before extrapolating information to areas beyond the data collected, managers should account for local differences in the availability, arrangement, and scaling of resources.

Fine-scale habitat selection limits trade-offs between foraging and temperature in a grassland bird

Many species are frequently faced with the decision about how to balance the use of thermal refuge against access to food resources. We evaluated the habitat use of female greater prairie chickens (Tympanuchus cupido) to assess the potential for trade-offs between thermal conditions and food resources during the habitat selection process. Our objectives were to 1) compare near-ground temperatures, invertebrate availability, and vegetation characteristics at sites used by greater prairie chickens to conditions at random landscape locations in various time since fire patches and 2) assess changes in conditions at used sites throughout the day to determine if selection for resources changes relative to ambient conditions, resulting in trade-offs between foraging sites and thermal refuge. We found that greater prairie chickens primarily used patches 0–12 months postfire that had relatively high abundances and biomasses of invertebrates compared to other time since fire patches. Greater prairie chickens further modified their selection at relatively fine spatial scales within these food-rich patches to select for areas with cooler temperatures during the hottest part of the day. The use of thermal refuge did not appear to influence the access to food resources as invertebrate abundance and biomass at used sites were consistent throughout the day. Our results show that food resources and thermal cover influences habitat selection for greater prairie chickens, but there was little evidence for trade-offs during the habitat selection process. Consideration of spatial and temporal scales is critical for evaluating trade-offs in habitat selection for animals and this research provides insights into the decision-making process by prairie chickens.

Effects of fire on ground-dwelling arthropods in a shrub-dominated grassland

Arthropods are abundant and diverse animals in many terrestrial food webs. In western Oklahoma, some shrublands are interspersed with discrete, dense thickets of tall, woody vegetation, known as mottes. Some of these shrublands are managed with prescribed burning. The goal of this study was to examine whether prescribed burning interacted with habitat type (i.e., shrubland versus mottes) to affect ground-dwelling arthropod communities. Arthropods were collected in pitfall traps at four sampling locations in relation to mottes; in the center of mottes, and three plot location in shrublands; 1 m, 15 m, and 50 m away from the edge of the motte. There were three treatment levels for burning: one year postburn (burned in dormant months of 2017), two years postburn (burned in dormant months of 2016), and unburned (burned in dormant season of 2014 and prior). There were no significant interactions between prescribed burning and habitat type. Mottes had a different community of arthropods compared with the surrounding shrubland. Mottes also had lower overall abundance, but a higher diversity of arthropods. In terms of fires, arthropod communities one year after burning were different from those two or more years after burning. There was no effect of burning on overall arthropod abundance, but plots that were one year since burning had significantly lower diversity compared with plots that were two or more years postburn. The results of this study suggest that both fire and mottes can independently facilitate heterogeneity in arthropod communities, but they do not appear to interact with one another.

Role of the thermal environment in scaled quail (Callipepla squamata) nest site selection and survival

Temperature is increasingly recognized as an important component of wildlife habitat. Temperature is particularly important for avian nest sites, where extreme temperatures can influence adult behavior, embryonic development, and survival. For species inhabiting arid and semiarid climates, such as the scaled quail (Callipepla squamata), frequent exposure to extreme temperatures may increase the importance of the nest microclimate. Limited data suggest that scaled quail respond to temperature when selecting nest sites, and they are also known to respond to the presence of surface water and shrub cover on the landscape, two resources which may mitigate thermal stress. To better understand the role of temperature in nest site selection and survival, and to evaluate how other landscape resources may benefit nesting quail, we investigated nest site characteristics of scaled quail in southeastern New Mexico, USA. During the breeding seasons of 2018 and 2019 we located nests, monitored nest fate, and recorded thermal and vegetation characteristics at three spatial scales: the nest bowl, the nest microsite (area within 10 m of the nest bowl), and the landscape. We found that nest bowls moderated temperature relative to both the surrounding microsite and the broader landscape, remaining almost 5 °C cooler on average than the surrounding microsite at mid-day. Nest bowls also had taller, greater cover of vegetation compared to both the surrounding microsites and the landscape. Despite apparent selection for cooler temperatures and taller vegetation, these characteristics demonstrated a weak relationship with nest survival. Rather, nest survival was positively influenced by proximity to surface water and honey mesquite (Prosopis glandulosa), with survival decreasing with increasing distance from these features. Although the mechanism for this relationship is unclear, our results support the importance of temperature for nest site selection of ground-nesting birds in semiarid landscapes, and suggest further exploration of landscape-level sources of thermal mitigation.

Behavioral modifications lead to disparate demographic consequences in two sympatric species

Life-history theory suggests species that typically have a large number of offspring and high adult mortality may make decisions that benefit offspring survival in exchange for increased adult risks. Such behavioral adaptations are essential to understanding how demographic performance is linked to habitat selection during this important life-history stage. Though studies have illustrated negative fitness consequences to attendant adults or potential fitness benefits to associated offspring because of adaptive habitat selection during brood rearing, equivocal relationships could arise if both aspects of this reproductive trade-off are not assessed simultaneously. To better understand how adaptive habitat selection during brood rearing influences demographics, we studied the brood survival, attendant parental survival, and space use of two sympatric ground-nesting bird species, the northern bobwhite (hereafter: "bobwhite"; Colinus virgininanus) and scaled quail (Callipepla squamata). During the 2013-2014 breeding seasons, we estimated habitat suitability across two grains (2 m and 30 m) for both species and determined how adult space use of these areas influenced individual chick survival and parental risk. We found the proportion of a brood's home range containing highly suitable areas significantly increased bobwhite chick survival (β = 0.02, SE = 0.006). Additionally, adult weekly survival for bobwhite was greater for individuals not actively brooding offspring (0.9716, SE = 0.0054) as compared to brooding adults (0.8928, SE = 0.0006). Conversely, brood habitat suitability did not influence scaled quail chick survival during our study, nor did we detect a survival cost for adults that were actively brooding offspring. Our research illustrates the importance of understanding life-history strategies and how they might influence relationships between adaptive habitat selection and demographic parameters.

Coerced resilience in fire management

Mechanisms underlying the loss of ecological resilience and a shift to an alternate regime with lower ecosystem service provisioning continues to be a leading debate in ecology, particularly in cases where evidence points to human actions and decision-making as the primary drivers of resilience loss and regime change. In this paper, we introduce the concept of coerced resilience as a way to explore the interplay among social power, ecological resilience, and fire management, and to better understand the unintended and undesired regime changes that often surprise ecosystem managers and governing officials. Philosophically, coercion is the opposite of freedom, and uses influence or force to gain compliance among local actors. The coercive force imposed by societal laws and policies can either enhance or reduce the potential to manage for essential structures and functions of ecological systems and, therefore, can greatly alter resilience. Using a classical fire-dependent regime shift from North America (tallgrass prairie to juniper woodland), and given that coercion is widespread in fire management today, we quantify relative differences in resilience that emerge in a policy-coerced fire system compared to a theoretical, policy-free fire system. Social coercion caused large departures in the fire conditions associated with alternative grassland and juniper woodland states, and the potential for a grassland state to emerge to dominance became increasingly untenable with fire as juniper cover increased. In contrast, both a treeless, grassland regime and a co-dominated grass-tree regime emerged across a wide range of fire conditions in the absence of policy controls. The severe coercive forcing present in fire management in the Great Plains, and corresponding erosion of grassland resilience, points to the need for transformative environmental governance and the rethinking of social power structures in modern fire policies.

Determinants of perceived risk and liability concerns associated with prescribed burning in the United States

While prescribed burning is a proven tool in the management of forests and grasslands, its use has been limited due, in part, to potential risks that may result in legal liability, property damage, and personal injury. The purpose of this study is to understand the factors that shape landowners' and fire professionals' perceptions of risks associated with prescribed burning activities. The data for this study were collected from active prescribed fire professionals involved in Prescribed Burn Association (PBA) activities in 14 Southern and Mid-western states. Perceived risk was higher among respondents with higher levels of concern related to safety and weather but lower among respondents with more experience in burning activities. Sociodemographic variables such as age and income were not significantly correlated with risk perception. These findings are useful for better understanding how landowners and fire professionals perceive risk and offer insight into how perceived risk affects decisions to apply prescribed burns.

Thermal refuge affects space use and movement of a large-bodied galliform

Temperature affects every organism on Earth and has been argued to be one of the most critical factors influencing organisms' ecology and evolution. Most organisms are susceptible to landscape temperature ranges that exceed their thermal tolerance. As a result, the distribution of landscape features that mitigate thermal extremes can affect movement and space use of organisms. Using Rio Grande wild turkey (Meleagris gallopavo intermedia) as a model species, we measured black bulb temperature throughout the diurnal period and identified vegetation characteristics at wild turkey locations and random landscape locations. We observed that the thermal landscape was highly heterogeneous with temperature varying up to 52 °C at a given ambient temperature. Vegetation type strongly influenced temperature across space during daily peak heating, with taller vegetation types (woody vegetation >2 m) having mean temperatures up to 8.95 °C cooler than the remainder of the landscape. However, these cooler vegetation types were uncommon, only accounting for 8.2% of the landscape. Despite the rarity of tall woody cover, wild turkey showed strong selection for this vegetation type particularly during peak daily heating with 74.9% of locations within 18 m of tree cover. Not only did wild turkey alter space use across time relative to temperature variation, but they also altered movement. We found that on the hottest days (≥35 °C), wild turkeys decreased movement by three fold during peak heating, while movement on cooler days (<30 °C) was uniform. Collectively, our data provide evidence that space use and movement for large avian species can be influenced by the thermal environment, and that the thermal environment is an important component of habitat for a species.

Perspectives on grassland conservation efforts: should we rewild to the past or conserve for the future?

Grasslands are among the most imperilled biomes of the world. Identifying the most appropriate framework for restoring grasslands is dependent on the objectives of restoration, which is inherently determined by human priorities. Debates over the appropriate conservation model for grasslands have often focused on which species of herbivores should be the focus of restoration efforts. Here we discuss three perspectives of herbivore-based conservation in North American grasslands. First, the Pleistocene rewilding perspective is based upon the idea that early humans contributed to the demise of megafauna that were important to the evolution and development of many of North America's grasslands; therefore, their aim of restoration is rewilding of landscapes to pre-human times. Second, the bison rewilding perspective considers American bison a keystone herbivore that is culturally and ecologically important to North American grasslands. A third perspective focuses on restoring the pattern and processes of herbivory on grasslands and is less concerned about which herbivore is introduced to the landscape. We evaluate each of these three conservation perspectives in terms of a framework that includes a human domain, an herbivore domain and a biophysical domain. While all conservation perspectives partly address the three domains, they all fall short in key areas. Specifically, they fail to recognize that past, current and future humans are intimately linked to grassland patterns and processes and will continue to play a role in structuring grasslands. Furthermore, these perspectives seem to only superficially consider the role of fragmentation and climate change in influencing grassland patterns and processes. As such, we argue that future grassland conservation efforts must depend on the development of a model that better integrates societal, economic and policy objectives and recognizes climate change, fragmentation and humans as an integral part of these ecosystems.This article is part of the theme issue 'Trophic rewilding: consequences for ecosystems under global change'.

Moderate patchiness optimizes heterogeneity, stability, and beta diversity in mesic grassland

Heterogeneous disturbance patterns are fundamental to rangeland conservation and management because heterogeneity creates patchy vegetation, broadens niche availability, increases compositional dissimilarity, and enhances temporal stability of aboveground biomass production. Pyrodiversity is a popular concept for how variability in fire as an ecological disturbance can enhance heterogeneity, but mechanistic understanding of factors that drive heterogeneity is lacking. Mesic grasslands are examples of ecosystems in which pyrodiversity is linked strongly to broad ecological processes such as trophic interactions because grazers are attracted to recently burned areas, creating a unique ecological disturbance referred to as the fire-grazing interaction, or pyric herbivory. But several questions about the application of pyric herbivory remain: What proportion of a grazed landscape must burn, or how many patches are required, to create sufficient spatial heterogeneity and reduce temporal variability? How frequently should patches burn? Does season of fire matter? To bring theory into applied practice, we studied a gradient of grazed tallgrass prairie landscapes created by different sizes, seasons, and frequencies of fire, and used analyses sensitive to nonlinear trends. The greatest spatial heterogeneity and lowest temporal variability in aboveground plant biomass, and greatest plant functional group beta diversity, occurred in landscapes with three to four patches (25%-33% of area burned) and three- to four-year fire return intervals. Beta diversity had a positive association with spatial heterogeneity and negative relationship with temporal variability. Rather than prescribing that these results constitute best management practices, we emphasize the flexibility offered by interactions between patch number and fire frequency for matching rangeland productivity and offtake to specific management goals. As we observed no differences across season of fire, we recommend future research focus on fire frequency within a moderate proportion of the landscape burned, and consider a wider seasonal burn window.

Factors Affecting Public Preferences for Grassland Landscape Heterogeneity in the Great Plains

Agricultural intensification has fragmented rangelands in the Great Plains, which has contributed to uniform and homogeneous landscapes and decreased biodiversity. Alternative land management practices involving fire-grazing interactions can help maintain biodiversity without affecting livestock productivity. A survey was designed to understand the factors that influence preferences among the general population towards grassland landscape heterogeneity. Given the ordinal nature of survey responses, requisite data were analyzed using a generalized ordinal logit model. Results suggested that respondents who valued open space and those who recognized a need for a varying mix of uniform grasses and grasslands preferred landscape heterogeneity. Female respondents were about two times as likely to prefer heterogeneous landscapes compared to male respondents. In contrast, population groups that preferred wildlife habitat did not desire heterogeneous landscapes. Results suggest the need for extension and outreach activities to educate certain segments of the general population regarding benefits of alternative management practices that support landscape heterogeneity in the Great Plains.

Reproductive plasticity and landscape heterogeneity benefit a ground-nesting bird in a fire-prone ecosystem

Disturbance is critical for the conservation of rangeland ecosystems worldwide and many of these systems are fire dependent. Although it is well established that restoring fire as an ecological process can lead to increased biodiversity in grasslands and shrublands, the underlying mechanisms driving community patterns are poorly understood for fauna in fire-prone landscapes. Much of this uncertainty stems from the paucity of studies that examine the effects of fire at scales relevant to organism life histories. We assessed the response of a non-migratory ground-dwelling bird to disturbance (i.e., prescribed fire) and environmental stochasticity over the course of a 4-yr period, which spanned years of historic drought and record rainfall. Specifically, we investigated the nesting ecology of Northern Bobwhite (Colinus virginianus; hereafter Bobwhite) to illuminate possible avenues by which individuals respond to dynamic landscape patterns during a critical reproductive stage (i.e., nesting) in a mixed-grass shrubland in western Oklahoma, USA. We found that Bobwhites exhibited extreme plasticity in nest substrate use among time since fire categories (TSF) and subsequently maintained high nest survival (e.g., 57-70%). Bobwhites were opportunistic in nest substrate use among TSF categories (i.e., 72% of nest sites in shrubs in 0-12 months post fire compared to 71% in herbaceous vegetation in >36 months post fire), yet nesting decisions were first filtered by similar structural components (i.e., vertical and horizontal cover) within the vicinity of nest sites regardless of TSF category. Despite being a non-migratory and comparatively less mobile ground-nesting bird species, Bobwhites adjusted to dynamic vegetation mosaics on a fire-prone landscape under stochastic climatic conditions that culminated in stable and high nest survival. Broadly, our findings provide a unique depiction of organism response strategies to fire at scales relevant to a critical life-stage, a topic that has been previously understudied and poorly understood. We also demonstrate how doing so can better inform conservation practices aimed at restoring fire regimes on grassland and shrubland landscapes.

Pyric-carnivory: Raptor use of prescribed fires

Fire is a process that shaped and maintained most terrestrial ecosystems worldwide. Changes in land use and patterns of human settlement have altered fire regimes and led to fire suppression resulting in numerous undesirable consequences spanning individual species and entire ecosystems. Many obvious and direct consequences of fire suppression have been well studied, but several, albeit less obvious, costs of alteration to fire regimes on wildlife are unknown. One such phenomenon is the response of carnivores to fire events-something we refer to as pyric-carnivory. To investigate the prevalence of pyric-carnivory in raptors, we monitored 25 prescribed fires occurring during two different seasons and across two different locations in tallgrass prairie of the central United States. We used paired point counts occurring before and during prescribed fires to quantify the use of fires by raptors. We found a strong attraction to fires with average maximum abundance nearly seven times greater during fires than prior to ignitions (before: x¯ = 2.90, SE = 0.42; during: x¯ = 20.20; SE = 3.29) and an average difference between fire events and immediately before fires of 15.2 (±2.69) raptors. This result was driven by Swainson's hawks (Buteo swainsoni), which were the most abundant (n = 346) of the nine species we observed using fires. Our results illustrate the importance of fire as integral disturbance process that effects wildlife behavior through multiple mechanisms that are often overshadowed by the predominant view of fire as a tool used for vegetation management.

Incorporating abundance information and guiding variable selection for climate-based ensemble forecasting of species' distributional shifts

Ecological niche models (ENMs) have increasingly been used to estimate the potential effects of climate change on species’ distributions worldwide. Recently, predictions of species abundance have also been obtained with such models, though knowledge about the climatic variables affecting species abundance is often lacking. To address this, we used a well-studied guild (temperate North American quail) and the Maxent modeling algorithm to compare model performance of three variable selection approaches: correlation/variable contribution (CVC), biological (i.e., variables known to affect species abundance), and random. We then applied the best approach to forecast potential distributions, under future climatic conditions, and analyze future potential distributions in light of available abundance data and presence-only occurrence data. To estimate species’ distributional shifts we generated ensemble forecasts using four global circulation models, four representative concentration pathways, and two time periods (2050 and 2070). Furthermore, we present distributional shifts where 75%, 90%, and 100% of our ensemble models agreed. The CVC variable selection approach outperformed our biological approach for four of the six species. Model projections indicated species-specific effects of climate change on future distributions of temperate North American quail. The Gambel’s quail (Callipepla gambelii) was the only species predicted to gain area in climatic suitability across all three scenarios of ensemble model agreement. Conversely, the scaled quail (Callipepla squamata) was the only species predicted to lose area in climatic suitability across all three scenarios of ensemble model agreement. Our models projected future loss of areas for the northern bobwhite (Colinus virginianus) and scaled quail in portions of their distributions which are currently areas of high abundance. Climatic variables that influence local abundance may not always scale up to influence species’ distributions. Special attention should be given to selecting variables for ENMs, and tests of model performance should be used to validate the choice of variables.

Pyrodiversity is the coupling of biodiversity and fire regimes in food webs

Fire positively and negatively affects food webs across all trophic levels and guilds and influences a range of ecological processes that reinforce fire regimes, such as nutrient cycling and soil development, plant regeneration and growth, plant community assembly and dynamics, herbivory and predation. Thus we argue that rather than merely describing spatio-temporal patterns of fire regimes, pyrodiversity must be understood in terms of feedbacks between fire regimes, biodiversity and ecological processes. Humans shape pyrodiversity both directly, by manipulating the intensity, severity, frequency and extent of fires, and indirectly, by influencing the abundance and distribution of various trophic guilds through hunting and husbandry of animals, and introduction and cultivation of plant species. Conceptualizing landscape fire as deeply embedded in food webs suggests that the restoration of degraded ecosystems requires the simultaneous careful management of fire regimes and native and invasive plants and animals, and may include introducing new vertebrates to compensate for extinctions that occurred in the recent and more distant past.

This article is part of the themed issue ‘The interaction of fire and mankind’.

Restoring fire to grasslands is critical for migrating shorebird populations

Fire is a disturbance process that maintains the structure and function of grassland ecosystems while sustaining grassland biodiversity. Conversion of grasslands to other land uses coupled with altered disturbance regimes has greatly diminished the habitat available to many grassland-dependent species. These changes have been linked to declines in breeding bird populations, but may also be critical for migrating bird populations such as those shorebird species that depend on mesic grasslands during migration. We examined migratory shorebird use of burned grasslands in the southern Great Plains of North America using DISTANCE sampling to estimate and compare bird densities across recently burned and not recently burned landscapes (1-5 yr post fire). We conducted two surveys per week for 8-10 weeks along a 54-km route starting at the end of March and concluding in mid-May during 2014-2015. We encountered 2,509 total shorebirds in recently burned areas compared to 130 individuals in areas that were unburned. Fire was a major attractant for our three focal species with American Golden-plover (Pluvialis dominica), Upland Sandpiper (Bartramia longicauda), and Killdeer (Charadrius vociferus) densities of 20.48, 11.09, and 26.09 birds/km² in burned areas compared with 0.00, 1.27, and 0.92 birds/km² in unburned areas, respectively. This research illustrates the importance of burned grassland for migrating shorebirds, a phenomenon that has largely gone unreported previously. Generally, these findings add to a body of knowledge that demonstrates the value of managing grasslands with historic disturbances that vary over space and time. The application of these findings should improve decision-making for shorebird conservation and provides evidence that prescribed fire planning should include consideration for breeding, transient, and non-breeding populations that vary in their temporal use of the landscape.

Using a historic drought and high-heat event to validate thermal exposure predictions for ground-dwelling birds

Deviations from typical environmental conditions can provide insight into how organisms may respond to future weather extremes predicted by climate modeling. During an episodic and multimonth heat wave event (i.e., ambient temperature up to 43.4°C), we studied the thermal ecology of a ground-dwelling bird species in Western Oklahoma, USA. Specifically, we measured black bulb temperature (Tbb) and vegetation parameters at northern bobwhite (Colinus virginianus; hereafter bobwhite) adult and brood locations as well as at stratified random points in the study area. On the hottest days (i.e., ≥39°C), adults and broods obtained thermal refuge using tall woody cover that remained on average up to 16.51°C cooler than random sites on the landscape which reached >57°C. We also found that refuge sites used by bobwhites moderated thermal conditions by more than twofold compared to stratified random sites on the landscape but that Tbb commonly exceeded thermal stress thresholds for bobwhites (39°C) for several hours of the day within thermal refuges. The serendipitous high heat conditions captured in our study represent extreme heat for our study region as well as thermal stress for our study species, and subsequently allowed us to assess ground-dwelling bird responses to temperatures that are predicted to become more common in the future. Our findings confirm the critical importance of tall woody cover for moderating temperatures and functioning as important islands of thermal refuge for ground-dwelling birds, especially during extreme heat. However, the potential for extreme heat loads within thermal refuges that we observed (albeit much less extreme than the landscape) indicates that the functionality of tall woody cover to mitigate heat extremes may be increasingly limited in the future, thereby reinforcing predictions that climate change represents a clear and present danger for these species.

Influence of olfactory and visual cover on nest site selection and nest success for grassland-nesting birds

Habitat selection by animals is influenced by and mitigates the effects of predation and environmental extremes. For birds, nest site selection is crucial to offspring production because nests are exposed to extreme weather and predation pressure. Predators that forage using olfaction often dominate nest predator communities; therefore, factors that influence olfactory detection (e.g., airflow and weather variables, including turbulence and moisture) should influence nest site selection and survival. However, few studies have assessed the importance of olfactory cover for habitat selection and survival. We assessed whether ground-nesting birds select nest sites based on visual and/or olfactory cover. Additionally, we assessed the importance of visual cover and airflow and weather variables associated with olfactory cover in influencing nest survival. In managed grasslands in Oklahoma, USA, we monitored nests of Northern Bobwhite (Colinus virginianus), Eastern Meadowlark (Sturnella magna), and Grasshopper Sparrow (Ammodramus savannarum) during 2015 and 2016. To assess nest site selection, we compared cover variables between nests and random points. To assess factors influencing nest survival, we used visual cover and olfactory-related measurements (i.e., airflow and weather variables) to model daily nest survival. For nest site selection, nest sites had greater overhead visual cover than random points, but no other significant differences were found. Weather variables hypothesized to influence olfactory detection, specifically precipitation and relative humidity, were the best predictors of and were positively related to daily nest survival. Selection for overhead cover likely contributed to mitigation of thermal extremes and possibly reduced detectability of nests. For daily nest survival, we hypothesize that major nest predators focused on prey other than the monitored species' nests during high moisture conditions, thus increasing nest survival on these days. Our study highlights how mechanistic approaches to studying cover informs which dimensions are perceived and selected by animals and which dimensions confer fitness-related benefits.

Extreme climatic events constrain space use and survival of a ground-nesting bird

Two fundamental issues in ecology are understanding what influences the distribution and abundance of organisms through space and time. While it is well established that broad-scale patterns of abiotic and biotic conditions affect organisms' distributions and population fluctuations, discrete events may be important drivers of space use, survival, and persistence. These discrete extreme climatic events can constrain populations and space use at fine scales beyond that which is typically measured in ecological studies. Recently, a growing body of literature has identified thermal stress as a potential mechanism in determining space use and survival. We sought to determine how ambient temperature at fine temporal scales affected survival and space use for a ground-nesting quail species (Colinus virginianus; northern bobwhite). We modeled space use across an ambient temperature gradient (ranging from -20 to 38 °C) through a maxent algorithm. We also used Andersen-Gill proportional hazard models to assess the influence of ambient temperature-related variables on survival through time. Estimated available useable space ranged from 18.6% to 57.1% of the landscape depending on ambient temperature. The lowest and highest ambient temperature categories (<-15 °C and >35 °C, respectively) were associated with the least amount of estimated useable space (18.6% and 24.6%, respectively). Range overlap analysis indicated dissimilarity in areas where Colinus virginianus were restricted during times of thermal extremes (range overlap = 0.38). This suggests that habitat under a given condition is not necessarily a habitat under alternative conditions. Further, we found survival was most influenced by weekly minimum ambient temperatures. Our results demonstrate that ecological constraints can occur along a thermal gradient and that understanding the effects of these discrete events and how they change over time may be more important to conservation of organisms than are average and broad-scale conditions as typically measured in ecological studies.