Endangered Species II

Contributed Oral

Group Size Mediates Effects of Forest Structure on Productivity in a Recovering Social Woodpecker Population
James Garabedian, Christopher Moorman, M. Nils Peterson, John Kilgo

Conservation of endangered social wildlife in disturbance-prone forests is challenging because direct and indirect effects of management strategies developed at the time of species’ listing when population density is low may change under higher density conditions in recovered populations. Our objective was to evaluate direct and indirect drivers of productivity in the federally endangered red-cockaded woodpecker (Dryobates borealis; RCW) on Savannah River Site, SC. We used piecewise structural equation modeling to estimate direct and indirect relationships among RCW group size, fledgling production, group density, acreage treated with prescribed fire, and habitat acreage satisfying thresholds for large pines (>22 stems/ha of pines >35.6 cm dbh), hardwood midstory (<1.4 m2/ha BA of hardwoods 7.6–22.9 cm dbh), and hardwood canopy cover (<6%). We also tested whether group size mediated effects of habitat acreage satisfying thresholds on fledgling production. Increases in acreage treated with prescribed fire and habitat satisfying thresholds for large pines and hardwood midstory had direct positive effects on group size. Group size and acreage treated with prescribed fire had direct positive effects on fledgling production, whereas effects of acreage satisfying habitat thresholds were indirect and mediated by group size. Our results support our hypothesis that group size mediated positive effects of habitat thresholds on fledgling production. Management aimed to increase acreage of habitat satisfying thresholds for large pines and hardwood midstory will promote large group sizes, which in turn improve fledgling production. Additionally, positive effects of prescribed fire on group size and fledgling production indicate prescribed fire has unique contributions to woodpecker productivity, likely via direct effects on forest structure and potentially indirect effects on arthropod prey. By simultaneously accounting for multiple drivers of productivity, our study contributes to the understanding of how increases in social wildlife populations can alter previously documented direct effects of habitat quality on productivity.

Synthesis of Red-Cockaded Woodpecker Management Strategies and Suggestions for Regional Specificity in Future Management
Paige Ferguson, Franco Gigliotti, Emily Martin

The Red-cockaded Woodpecker (Dryobates borealis, RCW) was listed under the U.S. Endangered Species Act in 1973, and the species has been intensively managed since. We conducted a literature review of 120 papers to evaluate management strategies commonly used to conserve the RCW, emphasizing studies conducted after publication of the most recent Recovery Plan in 2003, to evaluate the efficacy of each strategy across the RCW’s range and identify demographic and environmental factors that influence the success of each strategy. Outcomes from prescribed fire vary the most across the RCW’s range because prescribed fire is influenced by the site’s vegetation, abiotic conditions, and land use history. Southern flying squirrel (Glaucomys volans) control is only a high priority in small RCW populations. The long-term effectiveness of artificial cavities and translocations, which are highly effective across the RCW’s range in the short-term, requires suitable habitat, which is strongly influenced by prescribed fire. Regional variation in RCW management may be needed because populations that are not in archetypical suitable habitat may benefit from management methods that are not suitable for large populations in archetypical habitats (e.g. installing many cavity restrictor plates and cavity inserts). We encourage consideration of how management should vary according to population demographics and site characteristics because multiple studies indicated a disconnect between the Recovery Plan’s range-wide habitat thresholds and observed RCW population growth rates. RCW management strategies have been studied most in the South Central Plains (n = 58 management strategy evaluations), and more research in other ecoregions (e.g., Southern Coastal Plain, n = 17; Middle Atlantic Coastal Plain, n = 6; and Ouachita Mountains, n = 5) would be valuable. The RCW, which inhabits broad geographic ranges and sites of varying productivity and will continue to rely on management efforts after downlisting or delisting from the Endangered Species Act.

Balancing Siting of Future Wind-Energy Infrastructure and Associated Habitat Loss for Migrating Whooping Cranes
Kristen Ellis, Aaron Pearse, David Brandt, Mark Bidwell, Wade Harrell, Max Post van der Burg

Climate and land-use changes have contributed to novel disturbance regimes in many ecosystems, leading to considerable uncertainty about how species will respond to altered landscapes. A recent assessment revealed that endangered Whooping Cranes (Grus americana) avoid wind-energy infrastructure during migration. However, uncertainties regarding cumulative impacts of droughts, other human developments, and continued construction of wind towers may influence ongoing recovery efforts for Whooping Cranes. Using remote-telemetry locations from 57 individuals from 2010 to 2016 in the United States Great Plains, we examined the implications of cumulative disturbances and decisions about future wind tower construction on habitat selection by migrating Whooping Cranes. Whooping Cranes rarely used areas < 800 m from roads, < 5 km from towns, and < 5 km from wind towers. Drought occurrence and severity varied spatially and temporally across the migration corridor. Severe droughts elicited a greater avoidance of towns and wind towers by Whooping Cranes compared to non-drought conditions (although the 95% confidence interval overlapped 0 for wind towers). Whooping cranes did not avoid power lines during severe droughts, yet cranes did avoid power lines in non-drought conditions. Our results suggest that severe droughts and an increasing spatial footprint of wind towers in the Great Plains may collectively contribute to additional loss of available stopover habitat for migratory Whooping Cranes. Decision-based analyses are increasingly advocated to guide recovery planning for endangered species, yet applications remain rare. Thus, we suggest optimal scenarios for wind tower expansion, which are robust to uncertain drought conditions, to minimize future loss of highly selected migration habitats for this endangered species.

Spatially Explicit Modeling to Inform Conservation Triage for An At-Risk Species
Melissa Bauer, Adrienne Kovach

Habitat loss and fragmentation have imperiled wildlife globally, resulting in small populations at risk of decline without informed management intervention. To recover at-risk species, management needs to maintain small populations and restore landscapes that can support viable populations – a challenge given limited budgets, urgently declining populations, and uncertainty regarding population status and best management strategies. The New England cottontail (Sylvilagus transitionalis) has experienced dramatic decline in recent years from loss and fragmentation of shrubland habitat despite ongoing conservation efforts. With limited resources, managers are in the position of triaging declining populations to determine where habitat restoration and augmentation will have the most impact, or to support the difficult decision that some populations cannot be recovered. We parameterized a spatially explicit, individual-based model in a landscape genetics framework in CDMetaPOP to address questions of conservation triage in a small New England cottontail population in a highly fragmented, industrial landscape. We 1) determined the current extinction risk of the population; 2) compared alternate habitat restoration and augmentation scenarios (e.g., restoring small versus large patches, augmenting center versus peripheral patches); and 3) determined what habitat acreage and number of captive-bred cottontails are needed to maintain this population long-term – in other words, what does a viable New England cottontail metapopulation look like? Predictive models highlighted the importance of large source patches to maintain cottontail metapopulations – suggesting a need to refocus habitat management toward large projects, a challenge given land ownership patterns in New England. No feasible restoration scenarios allowed the population to grow to the Conservation Target size of 500 individuals, highlighting the need to re-assess Conservation Targets range-wide.

“Plover-View”: The Role of Nest-Site Visibility in Piping Plover Nest-Site Selection
Sharon Dorsey, James Fraser, Shannon Ritter, Daniel Catlin, Sarah Karpanty, Samantha Robinson, Katie walker

The piping plover (Charadrius melodus), an imperiled shorebird, usually nests in open sand. This is probably so incubating plovers can see terrestrial predators at a distance, allowing early initiation of distraction behavior. Microtopography and vegetation can obstruct visibility from a plover’s nest. Looking at a segment of Fire Island, New York as a case study, we conducted a viewshed analysis in ArcMap 10.7.1, in a use vs. availability framework, to test the hypothesis that plovers selected nest-sites with greater visibility than randomly selected sites. We expressed visibility as the percent of 15 cm pixels within 30 m of a nest or random point, that would be visible to a piping plover with a 6cm height of eye. Visible area at nest-sites and random points was the percent of area within 30 m of the nest or point not obscured by vegetation or microtopographic features such as tiny dunes or swales. Visible area at nest-sites declined from 2015 to 2019 (x̄ = 65.0%, n = 22 vs x̄ = 21.9%, n = 37) as vegetative succession proceeded following Hurricane Sandy, which removed or covered vegetation in 2012. From 2015–2019, piping plovers selected nest-sites (n = 130) with greater visible area within 30 m (x̄ = 30.0%), less vegetation coverage within 30 m (x̄ = 7.1%), and greater distance to vegetation  patches >100 m 2 (x̄ = 148.9m) than expected if they were selecting nest sites at random (logistic regression AIC = 584.8  vs. null model AIC = 686.0). While managers have long known that piping plovers select sparsely vegetated habitat, the importance of microtopography in habit selection is new. 

Genetic Diversity and Relatedness Among African Painted Dogs in North America
Cassandra Miller-Butterworth, Karen Vacco, Amy Russell, Joseph Gaspard

African painted dogs (Lycaon pictus, APD) are highly endangered, with fewer than 6,000 individuals remaining in the wild. With careful genetic management, captive breeding programs can preserve a genetically diverse population and potentially provide a source of individuals for re-introductions. However, most captive programs are initiated from few founders and may suffer from low genetic diversity and inbreeding, compounded by inaccuracies in the species studbook. The primary aims of this study were to use molecular markers to assess genetic variation, inbreeding, and relatedness among APDs in the North American captive population, to use these data to inform and, where necessary, realign studbook pedigree records, as well as to compare these data to those obtained previously for the European captive population to facilitate the development of a global management plan. Blood samples were collected opportunistically from 109 APDs from 34 institutions in North America. We sequenced 308 bp of the mitochondrial D-loop control region I and 340 bp of exon 2 of the DLA-DRB1 major histocompatibility (MHC) class II locus, and genotyped 14 nuclear microsatellite loci from each individual. Where it was possible to test parentage, the most likely genetic connections of parents and offspring were generally consistent with studbook records. However, we identified three likely errors in studbook records and resolved 10 cases of uncertain paternity. Overall, microsatellite heterozygosity of the APD population (HO = 0.832) is higher than that reported in Europe, but effective population size (Ne) estimates are lower. D-loop sequence variation is extremely limited with only 2 haplotypes and there are fewer MHC haplotypes than in Europe, one of which is over-represented. The population does not yet show signs of a genetic bottleneck or significant inbreeding. Nevertheless, a few individuals are highly inbred (r > 0.8), which should be taken into account during future breeding programs.

Optimizing Spatial Application of Habitat Management Actions for the Gunnison Sage-Grouse Satellite Populations
Jessica Shyvers, Nathan Van Schmidt, D. Joanne Saher, Julie Heinrichs, Cameron Aldridge

The Gunnison Sage-Grouse (Centrocercus minimus) is a species of conservation concern that is currently listed as threatened under the federal Endangered Species Act (1973). The species has experienced substantial and continuing declines in range-wide abundance and distribution, primarily due to loss of habitat. Gunnison Sage-grouse are predominantly restricted to seven populations in southwest Colorado, six of which are small, isolated satellites where numbers are currently declining or significantly below conservation objectives. Our objective was to assess the potential for targeted habitat management actions to improve habitats for these satellite populations using newly developed Resource Selection Function models mapped to each population. Our approach was to 1) identify the habitats likely to be most responsive to management actions that improve suitability for Gunnison Sage-grouse, 2) apply spatially representative habitat improvement scenarios based on the Bureau of Land Management’s current habitat actions for sage-grouse to gauge the benefits of different types of actions, and 3) recommend a suite of realistic, spatially-targeted actions that most improve sage-grouse habitat in each satellite population. Preliminary results show a wide range of sensitivity and expected responsiveness to habitat improvement actions, even among local site choices. This indicates that spatial targeting could increase the potential for return on conservation investments and demonstrates how local habitat management actions can be optimized for each satellite population to provide the most benefit given limited management resources.

Demography and Survival of Head-Started Blanding’s Turtles in An Artificially Restored Urban Wetland
Tharusha Wijewardena, Matthew Keevil, Nicholas Mandrak, Jacqueline Litzgus

Wildlife populations worldwide are negatively affected by urbanization. In addition to losing wetland habitats due to development, turtle populations in cities experience increased road and rail mortality, subsidized predators, decreased nesting success, and genetic isolation. The slow life history strategy of turtles makes their populations especially vulnerable to mortality resulting from urbanization. Studies on turtles in urban areas have shown significant declines in population sizes, leading to functional extinction before extirpation, and deleterious changes in population structures. A functionally extinct population of globally endangered Blanding’s Turtles (Emydoidea blandingii) was discovered in one of the most populated areas in Canada, the Greater Toronto Area (GTA), and a head-start program was initiated in 2012 to recover the local population. A capture-mark-recapture (CMR) study was conducted from 2018 to 2020 with the aim of quantifying the population size, age distribution, sex ratio, and survivorship of the head-started Blanding’s Turtle population. A Jolly-Seber open population model will be used to estimate population size and survivorship of head-starts. Preliminary age distribution analyses showed that head-starts from older cohorts were recaptured more frequently compared to recent cohorts despite higher release numbers in recent cohorts. Sex ratio was assumed based on incubation temperature of eggs, and the pre-release and post-release sex ratios did not significantly differ. We plan to integrate radio-telemetry data in our CMR population model to increase precision of population size and survival estimates that will be used in a population viability analysis. The findings from our study will inform management decisions that are necessary for the long-term success of a head-start program on an endangered turtle species based in a rapidly changing urban habitat.

Contributed Oral
Location: Virtual Date: November 4, 2021 Time: 4:00 pm - 5:00 pm