Prey species can perceive and respond to spatiotemporal variation in predation risk to increase survival. In addition to adjusting spatial and temporal activity patterns to avoid predation, prey employ other antipredator behaviors, such as vigilance and fleeing, and these behaviors can be further modulated by intrinsic, environmental, and anthropogenic factors. However, few studies simultaneously examine multiple potential antipredator behavioral responses of prey or examine prey responses to multiple scales of risk. In the southeastern United States, coyotes (Canis latrans) have become established as the top predator of white-tailed deer (Odocoileus virginianus) populations mainly through fawn predation, and deer adjust behaviors in response to coyotes. Using passive camera trap data from summer 2019 to 2021, we simultaneously tested for evidence that deer adjust spatial activity patterns, diel activity patterns, and vigilance behavior in response to various abiotic and biotic factors including long-term and short-term coyote encounter risk. Overall, our results suggest that deer are unable to eliminate the risk of encountering coyotes by modifying their spatial activity and thus employ other demographic-specific behavioral adaptations to reduce coyote encounter risk. Deer nursery groups were significantly more diurnal than adult males or adult female deer traveling alone, likely in an attempt to reduce predation risk for fawns. Deer nursery groups increased spatial activity but decreased vigilance at sites the day following increased wild pig (Sus scrofa) activity, suggesting invasive competitors have impacts on maternal behaviors in deer. Adult female deer collectively increased vigilance at sites with greater long-term coyote encounter risk, and in support of the "many-eyes" hypothesis, were less vigilant when in larger groups. Spatial activity of adult female deer traveling alone was positively related to short-term coyote encounter risk, potentially indicating coyotes seek areas with increased doe activity to help locate fawn prey. The results of our study show that behavioral responses to predators and competitors are modulated by individual state (demography), grouping behavior, and habitat features. Our study highlights the need to analyze multiple potential antipredator behaviors and multiple scales of risk to gain a more complete understanding of prey responses to risk.
Population declines among sagebrush ( Artemisia spp.) reliant birds mirror the larger deterioration of the sagebrush ecosystem. To combat this biome decline, western partners have unified around a common vision for sagebrush conservation by developing the Sagebrush Conservation Design, which identified high-priority areas, designated as "core sagebrush areas" (CSAs), to anchor conservation actions throughout the biome. While this conservation design did not explicitly consider the distribution or abundance of focal species, an underlying assumption has been that sagebrush-associated wildlife will benefit from actions targeting threats to the sagebrush biome. Herein, we explicitly test whether sagebrush ecological integrity (SEI), the metric used to quantify CSAs, is associated with sagebrush songbird abundance and population trends, such that CSAs provide an effective umbrella for wildlife conservation. Because species likely vary in their response to different ecological factors, we further examined the relative importance of the five components of SEI: sagebrush cover, tree cover, perennial grass cover, annual grass cover, and human modification, in structuring sagebrush songbird populations. We found substantial increases in population counts associated with increased values of SEI across three species examined: sagebrush sparrow ( Artemisiospiza nevadensis), ), Brewer's sparrow ( Spizella breweri), ), and sage thrasher ( Oreoscoptes montanus). ). Specifically, models supported 10 times (sage thrasher), six times (Brewer's sparrow), and three times (sagebrush sparrow) higher median relative abundances in CSAs compared with surrounding areas. Further, we found strong evidence of large population declines as areas transitioned out of CSAs. Finally, although we found some species-specific differences in the relative importance of the five SEI components, generally, sagebrush cover and tree cover were more important than grass cover in influencing bird populations. We show that conservation actions designed to preserve or grow CSAs will likely benefit sagebrush-obligate songbird populations and other focal wildlife, especially if consideration is given to which component(s) of SEI are targeted. Published by Elsevier Inc. on behalf of The Society for Range Management. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )
AbstractUnderstanding the demographic drivers of reintroduced and translocated populations is critical for species establishment and persistence. Given the large number of resources required to conduct ongoing reintroduction and reinforcement programs, additional information on population responses to management practices could help identify key actions that best benefit a species while ensuring economic feasibility. An integrated population model (IPM) can be used to assess and forecast the demographic consequences of different management practices and the interrelationship between management effects, population dynamics, and environmental change. We used an IPM to inform the potential impacts of nest management practices and global climate change on the vital rates of the Texas nesting colony of the endangered Kemp's ridley sea turtle. We used the IPM to estimate population parameters including adult survival, population growth rate, and abundance of nesting females in Texas. Additionally, given potential future scenarios for management and environmental change, we used the IPM to forecast population change and estimate the probability of persistence of the Texas population under future environmental and management scenarios. Future scenarios for nest management that had some level of management (i.e., not all nests were left in situ) resulted in population growth rates that were likely stable or increasing. Scenarios in which all nests were left in situ resulted in stable or decreasing population growth rates as well as a probability of extirpation from Texas >1 (p(N = 0 in 2100) = 0.25–0.72). Despite uncertainty in forecasted abundance and population growth rates under all scenarios, our model still predicted stable or increasing population growth rates with a continuation of current nest management practices. In contrast, we found that reduced population growth was expected with reduced nest management effort, and population decline and extirpation was expected with no management. Our IPM framework provides an example of how future management scenarios can be evaluated critically to determine population changes through time under future environmental uncertainty.
Background Fire seasonality is important for forest managers to consider when restoring historical disturbance regimes and recovering native ecosystem structure and composition, but it is less understood and less frequently studied than other aspects of fire ecology. In the Southern Appalachians, historical fires likely occurred most often in late spring and early summer when fuels were dry and canopy conditions were conducive to fire; however, most prescribed fires today occur during the dormant season (January–March). Because fire behavior can vary seasonally, it is important for forest managers to understand the practical applications of fire season in order to burn at a time that meets management objectives. Therefore, we investigated the effect of fire seasonality on forest structure and land cover diversity in the Southern Appalachians. Results Using a complete randomized block design, we analyzed leaf-on canopy cover imagery with ArcGIS Pro to compare canopy cover and forest structure between growing and dormant season burns. We compared imagery between three blocks, each with an unburned control unit, dormant season burn, and growing season burn, and found an average of 8.84% (SE = ± 1.46) reduction in canopy cover in growing season treatment units from pre-burn (2017) to post-burn (2019) compared to 5.21% (SE = ± 1.51) reduction in dormant season treatment units and 0.01% (SE = ± 0.009) reduction in unburned controls. Canopy cover reductions corresponded with substantial increases in early- and mid-successional habitat, edge length, and land cover diversity — especially in growing season burn treatment units. Conclusions Our results indicate that early growing season burns are more effective than dormant season burns at enhancing forest structural heterogeneity. Early growing season burns, therefore, may be a viable option for forest managers looking to expand their burn season and achieve restoration and management goals faster than traditional dormant season burns.
South Carolina coastal and inland wetlands are continentally important to resident, migrating, and wintering dabbling ducks (Anatini), diving and sea ducks (Aythini, Mergini, Oxyurini), pelagic waterbirds (Anhingidae, Laridae, Pelicanidae, and Phalcrocoracidae), and wading birds (Ardeidaie, Ciconiidae, Threskiornithidae). Our goal was to model wetland selection of these waterbird guilds in South Carolina during autumn–winter to determine habitat preferences and guide wetland conservation and restoration amid sea‐level rise and other coastal pressures. We conducted aerial surveys and recorded waterbird occurrence and relative abundance in winters 2017–2019. We modeled waterbird–habitat relationships relative to managed and unmanaged coastal and inland wetlands, legally protected conservation lands (e.g. federal, state, and private easements), and habitat diversity. Waterbirds selected a variety of wetlands emphasizing the importance of wetland diversity within habitat complexes. However, only managed tidal impoundments (MTIs) and protected conservation lands were selected across all waterbird guilds. Results suggest these are contemporary keystone habitats for promoting wintering waterbird abundance and diversity in South Carolina and other South Atlantic coastal regions. To compensate for future coastal wetland loss while facilitating the current and future needs of migrating and wintering waterbirds, we recommend: (1) identification and continued management of MTIs resilient to sea‐level rise; (2) strategic planning and partnerships for land acquisition and legal protections inland; and (3) land protection networks between extant coastal and inland sites designated for future construction and emigration of decommissioned MTIs. Stakeholder and partner engagement is paramount to prioritize resource allocation for the restoration, construction, and decommissioning of coastal and inland wetlands.
Although managing habitats in the context of climate change is increasingly important in Western North America, management recommendations are often lacking at fine scales relevant for management. Identifying management actions for climate adaptation requires an understanding of how wildlife (i) might vary in their response to habitat conditions across their range and (ii) the spatial scale of environmental effects. We quantified breeding habitat use of the Interior population of Band-tailed Pigeons (Patagioenas fasciata) in the Southwestern U.S. by analyzing data from satellite-tagged birds with a resource selection function. We used Reversible-jump Markov chain Monte Carlo (RJMCMC) to quantify habitat use of Band-tailed Pigeons across vegetation, topography, and precipitation, examining the possibility for differences in habitat selection and estimated the most ecologically relevant spatio-temporal scale for these habitat features (i.e., the optimal "scale of effect"). Our RJMCMC results indicated that Band-tailed Pigeon intensity of use was characterized by precipitation x conifer cover and precipitation x basal area interactions. In drier areas, Band-tailed Pigeons were more likely to use areas with more conifer cover; as precipitation increased, Band-tailed Pigeons were more likely to use areas with less conifer cover. Increased precipitation facilitated greater use of forests with higher basal area, and drier areas were associated with use of forests with lower basal area. Conifer cover was primarily selected at the 1 km scale, and basal area was selected at the 2 km scale in response to precipitation during the winter preceding the breeding season. Although Band-tailed Pigeons have long been known to associate with conifer forests, we found that their use of conifer forest varied across a gradient of precipitation. Using our approach to select the scale of effect for forest habitat and basal area in response to changes in precipitation can provide more precise, spatially relevant habitat management recommendations than approaches using model selection such as Akaike's Information Criterion.
Understanding mechanistic causes of population change is critical for managing and conserving species. Integrated population models (IPMs) allow for quantifying population changes while directly relating environmental drivers to vital rates, but power of IPMs to detect trends and environmental effects on vital rates remains understudied. We simulated data for an IPM fewer than 41 scenarios to determine the power to detect trends and environmental effects on vital rates based on study duration, sample size, detection probability, and effect size. Our results indicated that temporal duration of a study and effect size, rather than sample size of each individual data set or detection probability, had the greatest influence on the power to identify trends in adult survival and fecundity. When using only 10 years of data, we were unable to identify a 50% increase in adult survival but were able to identify this increase with 22 years of data. When using only capture-recapture data in a traditional Cormack-Jolly-Seber analysis, we lacked sufficient power to identify trends in survival, and power of the Cormack-Jolly-Seber model was always less than the IPM. The IPM had greater power to identify trends and environmental effects on fecundity (e.g., we detected a 58% change in fecundity using 12 years of data). Models with effects of environmental variables on vital rates had less power than trends, likely to be due to increased annual variation in the vital rate when modeling responses to environmental effects that varied by year. Lack of power in the Cormack-Jolly-Seber analysis could be due to the relatively small variability in adult survival compared with fecundity, given the life history of our simulated species. As interannual variation in environmental conditions will probably increase with climate change, this type of analysis can help to inform the study duration needed, which may be a shifting target given future climate uncertainty and the complex nature of environmental correlations with demography.
The Migratory Bird Treaty Act (MBTA) is critical to avian conservation in the United States, both through its protection of migratory birds and as a catalyst for a century of coordinated avian conservation. While more than 1,000 species are protected by MBTA, of extant bird species native to the continental U.S., only 20 species belonging to the order Galliformes are explicitly excluded. Management of galliforms has occurred largely without direct federal oversight, placing this group on a fundamentally different conservation path during the century following MBTA passage. In this paper, we review the historical context and biological justification for exclusion of galliforms from MBTA and synthesize how their present-day conservation differs from that of migratory birds. We find the most prominent difference between the two groups involves the scope of coordination among stakeholders. The U.S. government, primarily via the Department of Interior, acts as de facto coordinating body for migratory bird conservation and plays the central role in oversight, funding, and administration of management in the United States. In contrast, galliform management falls primarily to individual state wildlife agencies, and coordinated conservation efforts have been more ad hoc and unevenly spread across species. Migratory birds benefit from an almost universally greater scope of research and monitoring, scale of habitat conservation, and sophistication of harvest management compared with galliforms. Galliform harvest management plans, in particular, are less likely to use measurable objectives, reporting of uncertainty in population parameters, and explanation of harvest management techniques. Based on a review of species status lists (e.g., the U.S. Endangered Species Act), we found no evidence that galliforms were more frequently listed than migratory species. Regional trend estimates from the North American Breeding Bird Survey (BBS) were more likely to be negative for galliforms over the period 1966-2015, but this was primarily driven by Northern Bobwhite (Colinus virginianus). Data to assess galliform population status are generally poor, which complicates assessment for roughly half of galliform species. Increased support for coordination among state agencies and other stakeholders, similar to that applied to migratory birds, could help to ensure that galliform conservation is poised to tackle forthcoming challenges associated with global change. Lay Summary center dot The Migratory Bird Treaty Act (MBTA) is a landmark piece of U.S. federal legislation that provided a mechanism for the protection of migratory birds via international treaty. center dot More than 1,000 species are protected by MBTA, however, 20 birds both native and resident to the continental U.S. are excluded from protection. All belong to the order Galliformes (grouse, quail, turkey, and chachalaca). center dot Galliform conservation has differed fundamentally from migratory birds over the last 100 years, where individual state wildlife agencies conduct management largely absent direct federal oversight. Coordinated conservation has been more ad hoc and unevenly spread across species as a result, and harvest management has been less well-developed, compared with migratory birds. center dot We found no evidence that galliforms were more frequently included on conservation status lists than migratory species. Regional trend estimates from the North American Breeding Bird Survey (BBS) were more likely to be negative for galliforms, but this was largely driven by a single species, the Northern Bobwhite (Colinus virginianus). center dot Increased support for coordination among state agencies and other stakeholders, similar to that applied to migratory birds, could benefit galliform conservation.
Temperate-breeding, or resident, Canada geese were once extirpated in Kansas, USA, but currently provide abundant viewing and hunting opportunities. Kansas Department of Wildlife, Parks, and Tourism (KDWPT) began reintroducing geese in 1980 with a goal of re-establishing a breeding population. Successful reintroductions led to translocating flocks to regions with no previous records of nesting geese; however, KDWPT continues to translocate individuals from nuisance flocks in urban areas to rural reservoirs to reduce human conflicts with urban geese. Our goal was to determine the effects of such translocations on survival and recovery of adult, sub-adult, and juvenile temperate-breeding Canada geese. We used Brownie dead-recovery models in Program MARK to compare survival and recovery probabilities between translocated and nontranslocated (normal wild) Kansas-banded Canada geese for 2012-2017. Model-estimated annual survival differed between status (normal wild S<^> = 0.761, 95% CI 0.734-0.785; translocated S<^> = 0.598, 95% CI 0.528-0.665). Recovery probability differed between normal and translocated adults (normal wild f<^> = 0.074, 95% CI = 0.069-0.078; translocated f<^> = 0.138, 95% CI = 0.120-0.158) and juveniles (normal wild f<^> = 0.067, 95% CI = 0.059-0.075; translocated f<^> = 0.250, 95% CI = 0.199-0.310). Recovery probability did not differ between status in the sub-adult age class (normal wild f<^> = 0.126, 95% CI = 0.115-0.137; translocated f<^> = 0.090, 95% CI = 0.055-0.144). Translocation is a viable management option to successfully reduce survival and increase recovery probability of urban nuisance geese in Kansas.
ABSTRACTAtlantic brant (Branta bernicla hrota) are important game birds in the Atlantic Flyway and several long‐term monitoring data sets could assist with harvest management, including a count‐based survey and demographic data. Considering their relative strengths and weaknesses, integrated analysis to these data would likely improve harvest management, but tools for integration have not yet been developed. Managers currently use an aerial count survey on the wintering grounds, the mid‐winter survey, to set harvest regulations. We developed an integrated population model (IPM) for Atlantic brant that uses multiple data sources to simultaneously estimate population abundance, survival, and productivity. The IPM abundance estimates for data from 1975–2018 were less variable than annual mid‐winter survey counts or Lincoln estimates, presumably reflecting better accounting for observer error and incorporation of demographic estimates by the IPM. Posterior estimates of adult survival were high (0.77–0.87), and harvest rates of adults and juveniles were positively correlated with more liberal hunting regulations (i.e., hunting days and the daily bag limit). Productivity was variable, with the percent of juveniles in the winter population ranging from 1% to >40%. We found no evidence for environmental relationships with productivity. Using IPM‐predicted population abundances rather than mid‐winter survey counts alone would have meant fewer annual changes to hunting regulations since 2004. Use of the IPM could improve harvest management for Atlantic brant by providing the ability to predict abundance before annual hunting regulations are set, and by providing more stable hunting regulations, with fewer annual changes. © 2021 The Wildlife Society.
Abstract While the Atlantic Coast of the United States and Canada is a major wintering area for sea ducks, knowledge about their wintering habitat use is relatively limited. Black Scoters have a broad wintering distribution and are the only open water species of sea duck that is abundant along the southeastern coast of the United States. Our study identified variables that affected Black Scoter (Melanitta americana) distribution and abundance in the Atlantic Ocean along the southeastern coast of the United States. We used aerial survey data from 2009 to 2012 provided by the United States Fish and Wildlife Service to identify variables that influenced Black Scoter distribution. We used indicator variable selection to evaluate relationships between Black Scoter habitat use and a variety of broad‐ and fine‐scale oceanographic and weather variables. Average time between waves, ocean floor slope, and the interaction of bathymetry and distance to shore had the strongest association with southeastern Black Scoter distribution.
Conservation efforts on private lands are important for biodiversity conservation. On private lands in South Carolina, in the southeastern United States, forestry management practices (prescribed burning, thinning, herbicide application) are used to improve upland pine habitat for wildlife and timber harvest and are incentivized through U.S. Department of Agriculture Farm Bill cost-share programs. Because many forest-dependent avian species have habitat requirements created primarily through forest management, data are needed on the effectiveness of these management activities. We studied privately owned loblolly pine (Pinus taeda) stands in the South Carolina Piedmont region. Our objective was to understand how management practices influence avian species richness and abundance at local (forest stand) and landscape levels in relatively small stands (average similar to 28 ha). We surveyed 49 forest stands during 2 bird breeding seasons with traditional point counts and vegetation surveys. We evaluated the effects of management on pine stand characteristics, avian species richness, and abundance of state-designated bird species of concern. Repeated burning and thinning shifted stand conditions to open pine woodlands with reduced basal area and herbaceous understories. Stands with lower basal area supported greater avian species richness. Some species increased in abundance in response to active management (e.g., Brown-headed Nuthatch [Sitta pusilla] and Indigo Bunting [Passerina cyanea]), but relationships varied. Some species responded positively to increases in forest quantity at a landscape scale (1-5 km; e.g., Northern Bobwhite [Colinus virginianus]). We found species-rich avian communities and species of conservation concern on working timber lands, indicating that incentivized forest management on private lands can provide valuable habitat for wildlife.
Abstract Loss and degradation of grasslands in the Great Plains region have resulted in major declines in abundance of grassland bird species. To ensure future viability of grassland bird populations, it is crucial to evaluate specific effects of environmental factors among species to determine drivers of population decline and develop effective conservation strategies. We used threshold models to quantify the effects of land cover and weather changes in "lesser prairie‐chicken" and "greater prairie‐chicken" (Tympanuchus pallidicinctus and T. cupido, respectively), northern bobwhites (Colinus virginianus), and ring‐necked pheasants (Phasianus colchicus). We demonstrated a novel approach for estimating landscape conditions needed to optimize abundance across multiple species at a variety of spatial scales. Abundance of all four species was highest following wet summers and dry winters. Prairie chicken and ring‐necked pheasant abundance was highest following cool winters, while northern bobwhite abundance was highest following warm winters. Greater prairie chicken and northern bobwhite abundance was also highest following cooler summers. Optimal abundance of each species occurred in landscapes that represented a grassland and cropland mosaic, though prairie chicken abundance was optimized in landscapes with more grassland and less edge habitat than northern bobwhites and ring‐necked pheasants. Because these effects differed among species, managing for an optimal landscape for multiple species may not be the optimal scenario for any one species.
Hellbenders Cryptobranchus alleganiensis are critically imperiled amphibians throughout the eastern USA. Rock-lifting is widely used to monitor hellbenders but can severely disturb habitat. We asked whether artificial shelter occupancy (the proportion of occupied shelters in an array) would function as a proxy for hellbender abundance and thereby serve as a viable alternative to rock-lifting. We hypothesized that shelter occupancy would vary spatially in response to hellbender density, natural shelter density, or both, and would vary temporally with hellbender seasonal activity patterns and time since shelter deployment. We established shelter arrays (n = 30 shelters each) in 6 stream reaches and monitored them monthly for up to 2 yr. We used Bayesian mixed logistic regression and model ranking criteria to assess support for hypotheses concerning drivers of shelter occupancy. In all reaches, shelter occupancy was highest from June-August each year and was higher in Year 2 relative to Year 1. Our best-supported model indicated that the extent of boulder and bedrock (hereafter, natural shelter) in a reach mediated the relationship between hellbender abundance and shelter occupancy. More explicitly, shelter occupancy was positively correlated with abundance when natural shelter covered <20% of a reach, but uncorrelated with abundance when natural shelter was more abundant. While shelter occupancy should not be used to infer variation in hellbender relative abundance when substrate composition varies among reaches, we showed that artificial shelters can function as valuable monitoring tools when reaches meet certain criteria, though regular shelter maintenance is critical.
Identifying the factors that determine the spatial distribution of biodiversity is a major focus of ecological research. These factors vary with scale from interspecific interactions to global climatic cycles. Wetlands are important biodiversity hotspots and contributors of ecosystem services, but the association between proportional wetland cover and species richness has shown mixed results. It is not well known as to what extent there is a relationship between proportional wetland cover and species richness, especially at the sub-continental scale. We used the National Wetlands Inventory (NWI) to model wetland cover for the conterminous United States and the National Land Cover Database to estimate wetland change between 2001 and 2011. We used a Bayesian spatial Poisson model to estimate a spatially varying coefficient surface describing the effect of proportional wetland cover on the distribution of amphibians, birds, mammals, and reptiles and the cumulative distribution of terrestrial endemic species. Species richness and wetland cover were significantly correlated, and this relationship varied both spatially and by taxonomic group. Rather than a continental-scale association, however, we found that this relationship changed more closely among ecoregions. The species richness of each of the five groups was positively associated with wetland cover in some or all of the Great Plains; additionally, a positive association was found for mammals in the Southeastern Plains and Piedmont of the eastern U.S. Model results indicated negative association especially in the Cold Deserts and Northern Lakes & Forests of Minnesota and Wisconsin, though these varied greatly between groups. Our results highlight the need for wetland conservation initiatives that focus efforts at the level II and III ecoregional scale rather than along political boundaries.
For migratory species such as Black Scoters (Melanitta americana) whose range encompasses a variety of habitats, it is especially important to obtain habitat use information across the species' range to better understand anthropogenic threats, e.g., marine development and climate change. The objective of our study was to investigate the winter movement patterns and habitat use of Black Scoters in the Atlantic Ocean by quantifying the following key movement indices: number of wintering sites, arrival and departure dates to and from the wintering grounds, days at a wintering site, area of a wintering site, distance between wintering sites, and differences in habitat features of wintering sites. We also tested if winter movement patterns varied by sex or along a latitudinal gradient. To quantify winter movement patterns of Black Scoters, we used satellite telemetry data from 2009 to 2012 (n = 29 tagged females and 15 males for a total of 66 winter seasons, 38 female winter seasons, 28 male winter seasons). Our results indicated that the average wintering site area and distance between wintering sites varied with latitude. Wintering sites located at southern latitudes were larger and further apart than wintering sites located at more northern latitudes. Additionally, wintering sites varied in bathymetry, distance to shore, and the slope of the ocean floor at different latitudes; northern wintering sites were in deeper waters, closer to shore, and on steeper slopes than southern wintering sites. Our results suggest that habitat use may differ by latitude, indicating that habitats used in northern locations may not be representative of habitats used in more southern wintering areas. Understanding variation of habitat use along a latitudinal gradient will enable managers to focus sampling effort for Black Scoter abundance and distribution along the Atlantic coast and provide insight on the wintering ecology and movement of Black Scoters.
Context Development of systematic methods for conservation planning has improved effectiveness and efficiency of implementing such plans. The lesser prairie-chicken ( Tympanuchus pallidicinctus ) is a grouse species of conservation concern native to the southwestern Great Plains of the United States. Recent lesser prairie-chicken conservation planning has involved identifying ecologically important areas but has not incorporated economic data into prioritization of areas to target for conservation management. Objectives We used the program Marxan to develop a decision-support tool for managers in Kansas to prioritize tracts for improving lesser prairie-chicken habitat quality and increasing habitat availability. We developed three different conservation scenarios and evaluated the tradeoffs among multiple planning objectives in these scenarios. Methods We incorporated population targets from an existing conservation plan and agricultural economic data to help select land with maximum ecological value and minimum economic productivity to prioritize for lesser prairie-chicken conservation. We compared potential conservation plans and incorporated a post hoc connectivity model to test potential for individuals to travel among habitat patches in these plans during dispersal events. Results We found that different conservation scenarios led to different solutions, though differences varied by ecoregion. Potential solutions for all scenarios contained habitat patches not currently included in existing conservation plans and had high connectivity potential. Conclusions These results provide context for spatial prioritization of lesser prairie-chicken habitat management in Kansas. Application of this approach to species of conservation interest could help managers incorporate socioeconomic factors into planning methods and identify important tracts for conservation currently overlooked by existing planning methods.
Researchers and managers are often interested in monitoring the underlying state of a population (e.g., abundance), yet error in the observation process might mask underlying changes due to imperfect detection and availability for sampling. Additional heterogeneity can be introduced into a monitoring program when male-based surveys are used as an index for the total population. Often, male-based surveys are used for avian species, as males are conspicuous and more easily monitored than females. To determine if male-based lek surveys capture changes or trends in population abundance based on female survival and reproduction, we developed a virtual ecologist approach using the lesser prairie-chicken (Tympanuchus pallidicinctus) as an example. Our approach used an individual-based model to simulate lek counts based on female vital rate data, included models where detection and lek attendance probabilities were <1, and was analyzed using both unadjusted counts and an N-mixture model to compare estimates of population abundance and growth rates. Using lek counts to estimate population growth rates without accounting for detection probability or density-based lek attendance consistently biased population growth rates and abundance estimates. Our results therefore suggest that lek-based surveys used without accounting for lek attendance and detection probability may miss important trends in population changes. Rather than population-level inference, lek-based surveys not accounting for lek attendance and detection probability may instead be better for inferring broad-scale range shifts of lesser prairie-chicken populations in a presence/absence framework.
Conservation of small populations is often based on limited data from spatially and temporally restricted studies, resulting in management actions based on an incomplete assessment of the population drivers. If fluctuations in abundance are related to changes in weather, proper management is especially important, because extreme weather events could disproportionately affect population abundance. Conservation assessments, especially for vulnerable populations, are aided by a knowledge of how extreme events influence population status and trends. Although important for conservation efforts, data may be limited for small or vulnerable populations. Integrated population models maximize information from various sources of data to yield population estimates that fully incorporate uncertainty from multiple data sources while allowing for the explicit incorporation of environmental covariates of interest. Our goal was to assess the relative influence of population drivers for the Lesser Prairie-Chicken (Tympanuchus pallidicinctus) in the core of its range, western and southern Kansas, USA. We used data from roadside lek count surveys, nest monitoring surveys, and survival data from telemetry monitoring combined with climate (Palmer drought severity index) data in an integrated population model. Our results indicate that variability in population growth rate was most influenced by variability in juvenile survival. The Palmer drought severity index had no measurable direct effects on adult survival or mean number of offspring per female; however, there were declines in population growth rate following severe drought. Because declines in population growth rate occurred at a broad spatial scale, declines in response to drought were likely due to decreases in chick and juvenile survival rather than emigration outside of the study area. Overall, our model highlights the importance of accounting for environmental and demographic sources of variability, and provides a thorough method for simultaneously evaluating population demography in response to long-term climate effects.
ABSTRACTUnderstanding the relative influence of environmental and intrinsic effects on populations is important for managing and conserving harvested species, especially those species inhabiting changing environments. Additionally, climate change can increase the uncertainty associated with management of species in these changing environments, making understanding factors affecting their populations even more important. Coastal ecosystems are particularly threatened by climate change; the combined effects of increasing severe weather events, sea level rise, and drought will likely have non‐linear effects on coastal marsh wildlife species and their associated habitats. A species of conservation concern that persists in these coastal areas is the mottled duck (Anas fulvigula). Mottled ducks in the western Gulf Coast are approximately 50% below target abundance numbers established by the Gulf Coast Joint Venture for Texas and Louisiana, USA. Although evidence for declines in mottled duck abundance is apparent, specific causes of the decrease remain unknown. Our goals were to determine where the largest declines in mottled duck population were occurring along the system of Texas Gulf Coast National Wildlife Refuges and quantify the relative contribution of environmental and intrinsic effects on changes to relative population density. We modeled aerial survey data of mottled duck density along the Texas Gulf Coast from 1986–2015 to quantify effects of extreme weather events on an index to mottled duck density using the United States Climate Extremes Index and Palmer Drought Severity Index. Our results indicate that decreases in abundance are best described by an increase in days with extreme 1‐day precipitation from June to November (hurricane season) and an increase in drought severity. Better understanding those portions of the life cycle affected by environmental conditions, and how to manage mottled duck habitat in conjunction with these events will likely be key to persistence of the species under future environmental conditions. © 2017 The Wildlife Society.