Red-cockaded Woodpecker Research Articles

Resin Production in Natural and Artificial Red-Cockaded Woodpecker Cavity Trees

Resin flow was measured in red-cockaded woodpecker (Picoides borealis Vieillot) clusters in longleaf pine (Pinus palustris Mill.) in the southern region of the Angelina National Forest, Texas. Resin flow (ml) at 1.4 m height over 24 hrs was measured from one 2.5 cm punch through the phloem between 0700 and 1000 hrs from March 1999 to September 2000, for a total of 9 measurements per tree. Resin was sampled in naturally active cavity trees, artificial (insert) active, natural inactive, artificial inactive and control pines (84 sample trees). Resin flow pattern was significantly different during the year, but not significantly different in the cavity tree type resin flow. Cavity trees in the 90th percentile (>33.0 ml resin in 24 hrs) were defined as super resin producing. High average resin flows in August 1999 and September 2000 indicate when to sample resin for potential cavity trees. Regression equations were produced to estimate future resin production.

Population models for social species: lessons learned from models of Red‐cockaded Woodpeckers (Picoides borealis).

Behavior can have major impacts on the population dynamics of social species and should be incorporated into demographic models to realistically evaluate population trends and extinction risk. We compared the predictions of a stage- and age-based matrix model, an individual-based model (IBM, developed in the program Vortex), and a spatially explicit individual-based model (SEPM) with the actual dynamics of a population of Red-cockaded Woodpeckers (RCW; Picoides borealis) in the Sandhills of North Carolina, USA. Predictions, including population size, composition, and growth rate, differed the most from actual population characteristics for models that did not incorporate social structure. The SEPM most closely predicted actual population dynamics, underestimating the population by 2.3%. This model, specifically developed to simulate RCW population dynamics, contains many of the features that we assert are important for adequately incorporating social behavior into demographic and population modeling. These features include the ability to (1) differentiate individuals based on their stage class, (2) capture the dynamics of the population at both the individual and group level, (3) incorporate the positive or negative effects of subdominants, (4) include environmental and demographic stochasticity, and (5) capture dispersal and other spatial factors. The RCW SEPM, although currently species-specific, provides a strong blueprint for how population models for social species could be constructed in the future when data allow.

A Minimally Invasive Method for Sampling Nest and Roost Cavities for Fungi: a Novel Approach to Identify the Fungi Associated with Cavity-Nesting Birds

Relationships among cavity-nesting birds, trees, and wood decay fungi pose interesting management challenges and research questions in many systems. Ornithologists need to understand the relationships between cavitynesting birds and fungi in order to understand the habitat requirements of these birds. Typically, researchers rely on fruiting body surveys to identify the fungal players in these relationships. Fruiting body surveys enable nondestructive sampling, but vastly underestimate fungal presence and diversity and may miss species of critical importance to cavity- nesting birds; thus new methods for such analyses are necessary. Here we present a novel technique to nondestructively sample the wood inside tree cavities, which produces samples that can be processed using DNA-based methods to identify fungi. We tested our method on Red-cockaded Woodpecker Picoides borealis excavations, half of which were from trees with Porodaedalea pini fruiting bodies. Using our new approach, we detected P. pini in 90% of the excavations in trees with fruiting bodies, but also in 60% of the excavations in trees without fruiting bodies and identified nine additional taxa of wood decay fungi that did not have fruiting bodies present. Our approach offers improved detection of fungi through non-destructive sampling of excavated cavities and we developed an improved primer specific to the fungal phylum that contains most wood decay fungi (Basidiomycota), thus providing managers and researchers a critical tool to better determine which fungi are important to cavity-nesting birds.

Carbon Tradeoffs of Restoration and Provision of Endangered Species Habitat in a Fire-Maintained Forest

Forests are a significant part of the global carbon cycle and are increasingly viewed as tools for mitigating climate change. Natural disturbances, such as fire, can reduce carbon storage. However, many forests and dependent species evolved with frequent fire as an integral ecosystem process. We used a landscape forest simulation model to evaluate the effects of endangered species habitat management on carbon sequestration. We compared unmanaged forests (control) to forests managed with prescribed burning and prescribed burning combined with thinning. Management treatments followed guidelines of the recovery plan for the endangered red-cockaded woodpecker (RCW), which requires low-density longleaf pine (Pinus palustris) forest. The unmanaged treatment provided the greatest carbon storage, but at the cost of lost RCW habitat. Thinning and burning treatments expanded RCW habitat by increasing the dominance of longleaf pine and reducing forest density, but stored 22% less total ecosystem carbon compared to the control. Our results demonstrate that continued carbon sequestration and the provision of RCW habitat are not incompatible goals, although there is a tradeoff between habitat extent and total ecosystem carbon across the landscape. Management for RCW habitat might also increase ecosystem resilience, as longleaf pine is tolerant of fire and drought, and resistant to pests. Restoring fire-adapted forests requires a reduction in carbon. However, the size of the reduction, the effects on sequestration rates, and the co-benefits from other ecosystem services should be evaluated in the context of the specific forest community targeted for restoration.

Cost-effective Recovery of an Endangered Species: The Red-cockaded Woodpecker

A model for the recovery of an endangered species is developed and applied to the redcockaded woodpecker (Picoides borealis), a species once abundant in the southeastern United States. There is a finite set of recovery actions that might be implemented in each period, with the goal of reaching a population target at some future date. Dynamic programming is used to solve deterministic and stochastic versions of the model. Least-cost recovery plans are found for the deterministic problem where it is possible to attain a population target with certainty. For the stochastic problem, least-cost, adaptive actions are identified.

Using mixed hidden Markov models to examine behavioral states in a cooperatively breeding bird

Lay Summary We use hidden Markov models to evaluate behavioral states and their relation to environmental, seasonal, and social factors in the endangered red-cockaded woodpecker. Woodpeckers showed 2 distinct behavioral states, resting and foraging, which were related to habitat quality, season, and group size. Our results reveal insights into underlying motivations of a social bird under different contexts and demonstrate the flexibility and utility of new tools for analyzing high-resolution animal tracking data.

Red-cockaded Woodpecker Microhabitat Characteristics and Reproductive Success in a Loblolly-Shortleaf Pine Forest

We investigated the relationship between red-cockaded woodpecker (Picoides borealis) reproductive success and microhabitat characteristics in a southeastern loblolly (Pinus taeda) and shortleaf (P. echinata) pine forest. From 1997 to 1999, we recorded reproductive success parameters of 41 red-cockaded woodpecker groups at the Bienville National Forest, Mississippi. Microhabitat characteristics were measured for each group during the nesting season. Logistic regression identified understory vegetation height and small nesting season home range size as predictors of red-cockaded woodpecker nest attempts. Linear regression models identified several variables as predictors of red-cockaded woodpecker reproductive success including group density, reduced hardwood component, small nesting season home range size, and shorter foraging distances. Red-cockaded woodpecker reproductive success was correlated with habitat and behavioral characteristics that emphasize high quality habitat. By providing high quality foraging habitat during the nesting season, red-cockaded woodpeckers can successfully reproduce within small home ranges.

Moro Big Pine: Conservation and Collaboration in the Pine Flatwoods of Arkansas

Established by a conservation easement in 2006, Moro Big Pine Natural Area-Wildlife Management Area (MBP) encompasses 16,000 contiguous acres in the pine flatwoods of southern Arkansas. This large-scale cooperative effort, focused on an ecosystem with high conservation value in a landscape increasingly dominated by planted, intensively managed loblolly pine (Pinus taeda), arose from an initiative by Potlatch Corporation, the State of Arkansas, and The Nature Conservancy (TNC). The MBP is a permanent easement purchased with a combination of public and private funds that seeks to balance the improvement of open pine woodlands with economic interests. Potlatch now manages the MBP under a prescription that ensures both timber production and forests capable of supporting the endangered red-cockaded woodpecker (Picoides borealis). State agencies, including the Arkansas Natural Heritage Commission, the Arkansas Game and Fish Commission, and the Arkansas Forestry Commission, have partnered with TNC and Potlatch to achieve a range of objectives, including the improvement of pine flatwoods, greater landscape connectivity, protection and habitat enhancement for species of special concern, and increased public access. Potlatch has also recently offered carbon credits from MBP to the California carbon market. MBP exemplifies some of the opportunities now available to private landowners and public agencies—a melding of conservation and production goals to protect working forests, improve ecosystem services, and provide recreational opportunities.

Geographic variation in fitness and foraging habitat quality in an endangered bird

Models are important tools for conservation, but the usefulness of any given model for decision-making depends on its accuracy and precision. Few models designed for conservation purposes are validated with real-world data, and such models are even less likely to be revisited and improved with post-implementation results. We test the performance of a model frequently used and heavily relied-upon for the management of the endangered red-cockaded woodpecker (Picoides borealis). The RCW Foraging Matrix Application incorporates spatially-explicit forest stand data and woodpecker territory locations to produce quantitative assessments of foraging habitat quality. Model parameters were based on expert opinion and research performed on several key populations at a time when range-wide habitat quality was relatively poor. Since the model’s inception, many red-cockaded woodpecker populations have been monitored intensely in restored habitat, providing an opportunity to evaluate model performance range-wide. We assessed the relationship of habitat quality, as measured by the RCW Matrix Application, to group size and fledgling production from populations across the species range in the southeastern United States. We also evaluated foraging habitat quality directly by relating woodpecker fitness components to foraging habitat metrics through regression tree analyses. Results showed that some, but not all, of the habitat metrics included in the RCW Matrix Application were consistently related to fitness components range-wide, but threshold values for these habitat metrics identified by regression tree analyses were site-specific rather than universal. Our findings indicate opportunities for improving on “one-size-fits-all” range-wide models with analyses of additional locally-relevant foraging habitat metrics.

Contrasting the ability of data to make inferences regarding dispersal: case study of the Red-cockaded woodpecker (Picoides borealis)

Dispersal is a critical biological process that contributes to the persistence of species in complex and dynamic landscapes. However, little is known about the ability of different types of data to reveal how species interact with landscape patterns during dispersal. Further, application of process-based, landscape-scale models able to capture the influence of land use and climate change are limited by this lack of dispersal knowledge. Here we highlight a method for building such models when dispersal parameters are unknown, but information on the mating system and survival are available. We applied a common statistical framework, rooted in information theory, to contrast the ability of abundance, movement, and genetic data to estimate dispersal parameters for endangered Red-cockaded woodpecker (RCW), using an individual-based, spatially-explicit population model. Dispersal was modeled as a multifaceted process in which foray distance, long-distance dispersal, competition for mates, and landscape permeability were treated as uncertain. We found that movement data are three-times more powerful than abundance data collected at the same spatial and temporal scales. However, habitat occupancy data collected over much a shorter time scale but at regional spatial scales were very effective for estimating dispersal. We also found that one-year of abundance data provided a similar reduction in uncertainty as genetic differences among breeding groups estimated using a 24-year pedigree. Substituting population genetic data for movement and abundance data often led to the same parameter values, but not always. Our study highlights important differences in the information content of data commonly collected in the field.

Systematic Review of the Influence of Foraging Habitat on Red‐Cockaded Woodpecker Reproductive Success

Relationships between foraging habitat and reproductive success provide compelling evidence of the contribution of specific vegetative features to foraging habitat quality, a potentially limiting factor for many animal populations. For example, foraging habitat quality likely will gain importance in the recovery of the threatened red‐cockaded woodpecker Picoides borealis (RCW) in the USA as immediate nesting constraints are mitigated. Several researchers have characterized resource selection by foraging RCWs, but emerging research linking reproductive success (e.g. clutch size, nestling and fledgling production, and group size) and foraging habitat features has yet to be synthesized. Therefore, we reviewed peer‐refereed scientific literature and technical resources (e.g. books, symposia proceedings, and technical reports) that examined RCW foraging ecology, foraging habitat, or demography to evaluate evidence for effects of the key foraging habitat features described in the species' recovery plan on group reproductive success. Fitness‐based habitat models suggest foraging habitat with low to intermediate pine Pinus spp. densities, presence of large and old pines, minimal midstory development, and herbaceous groundcover support more productive RCW groups. However, the relationships between some foraging habitat features and RCW reproductive success are not well supported by empirical data. In addition, few regression models account for > 30% of variation in reproductive success, and unstandardized multiple and simple linear regression coefficient estimates typically range from ‐0.100 to 0.100, suggesting ancillary variables and perhaps indirect mechanisms influence reproductive success. These findings suggest additional research is needed to address uncertainty in relationships between foraging habitat features and RCW reproductive success and in the mechanisms underlying those relationships.

Quantitative analysis of woodpecker habitat using high-resolution airborne LiDAR estimates of forest structure and composition

Light detection and ranging (LiDAR) technology has the potential to radically alter the way researchers and managers collect data on wildlife–habitat relationships. To date, the technology has fostered several novel approaches to characterizing avian habitat, but has been limited by the lack of detailed LiDAR-habitat attributes relevant to species across a continuum of spatial grain sizes and habitat requirements. We demonstrate a novel three-step approach for using LiDAR data to evaluate habitat based on multiple habitat attributes and accounting for their influence at multiple grain sizes using federally endangered red-cockaded woodpecker (RCW; Picoides borealis) foraging habitat data from the Savannah River Site (SRS) in South Carolina, USA. First, we used high density LiDAR data (10returns/m2) to predict detailed forest attributes at 20-m resolution across the entire SRS using a complementary application of nonlinear seemingly unrelated regression and multiple linear regression models. Next, we expanded on previous applications of LiDAR by constructing 95% joint prediction confidence intervals to quantify prediction error at various spatial aggregations and habitat thresholds to determine a biologically and statistically meaningful grain size. Finally, we used aggregations of 20-m cells and associated confidence interval boundaries to demonstrate a new approach to produce maps of RCW foraging habitat conditions based on the guidelines described in the species' recovery plan. Predictive power (R2) of regression models developed to populate raster layers ranged from 0.34 to 0.81, and prediction error decreased as aggregate size increased, but minimal reductions in prediction error were observed beyond 0.64-ha (4×4 20-m cells) aggregates. Mapping habitat quality while accounting for prediction error provided a robust method to determine the potential range of habitat conditions and specific attributes that were limiting in terms of the amount of suitable habitat. The sequential steps of our analytical approach provide a useful framework to extract detailed and reliable habitat attributes for a forest-dwelling habitat specialist, broadening the potential to apply LiDAR in conservation and management of wildlife populations.

Nest Site Selection and Reproductive Success of Red-cockaded Woodpeckers in Ocala National Forest

Red-cockaded woodpeckers (Picoides borealis) in the Ocala National Forest are located near the southern edge of the species' geographic range in a region that contains the largest contiguous area of sand pine scrub habitat endemic to Florida. We examined nest site selection and nest success of the species in this unique region to determine which habitat characteristics and management activities contribute most to woodpecker productivity. We used data from a single year (2010) to assess the relative importance of forest stand features, landscape features, management activities, and spatial characteristics affecting social behavior of the birds and found fire management practices played the largest role in habitat selection, while understory characteristics were most important to reproductive success. We also used data spanning an entire decade (2001 to 2010) to assess the relative importance of landscape features, management activities, spatial characteristics affecting social behavior of the birds, and environmental factors in habitat selection and productivity. We again found the number of fire events was most influential to habitat selection, whereas the location of clusters relative to the sand pine ecotone was most influential to reproductive success. Results highlight the well-known importance of using fire to maintain quality habitat for the species but also suggest some unique aspects pertinent to managing this southern population of red-cockaded woodpeckers.

Initial Ecosystem Restoration in the Highly Erodible Kisatchie Sandstone Hills

Restoration of the unique and diverse habitats of the Kisatchie Sandstone Hills requires the re-introduction of fire to reduce fuel accumulation and promote herbaceous vegetation, but some soils in the area are extremely erodible, and past fires have resulted in high erosion rates. Overstory and understory vegetation, downed woody fuels, and other stand attributes were measured on sites that received either no management or two prescribed burns after >20 years of fire exclusion. The two burns (one dormant season and one growing season) reduced the live fuel-load (understory biomass) and forest floor (litter and duff mass) by 90 and 71%, respectively, but did not change the downed woody fuel load. Understory plant diversity was not affected by burning, but burning stimulated both colonization and sprouting for most plant species. Habitat for Picoides borealis (Red-cockaded Woodpecker) was improved; understory plant height was reduced by 2 m, and herbaceous vegetation was found in 40% of the areas sampled in the burned sites but it was found in only 6.7% of the reference (unburned) sites. Erosion risk was still elevated due to the sparse vegetative cover on the forest floor. Future management should consider erosion prevention, and plan the timing and intensity of additional burns to maximize plant cover on the forest floor and to improve the habitat by converting the woody understory to an herbaceous understory.

Factors influencing loblolly pine stand health in Fort Benning, Georgia, USA

Loblolly pine (LBP; Pinus taeda L.) stands provides two-thirds of the existing federally protected red-cockaded woodpecker (RCW; Picoides borealis) habitat in Fort Benning, Georgia, USA. However, LBP in this area is suspected to face a forest decline issue, which may risk the sustainability of the RCW population. Land managers are attempting to convert LBP stands to longleaf pine (Pinus palustris Mill.), which once dominated the landscape, however the transition has to be gradual so current RCW habitat is maintained until longleaf pine stands sufficiently support RCW populations. It is critical to identify environmental factors influencing LBP health and convert LBP stands under poor environment to longleaf pine first. We installed 90 plots (30 × 30 m2) in mature (>38 years) loblolly pine forests and measured aspect, slope, soil texture, soil (pH, organic matter, cation exchange capacity, and exchangeable phosphorus, potassium, magnesium, and calcium) and foliar (nitrogen and phosphorus) nutrient, diameter at breast height, light exposure, and crown vigor class (CVC; 1 = good, 2 = fair, and 3 = poor). Stand age, site index, and burning and thinning history were retrieved from existing inventory data. Our results show that site index was the main factor in determining LBP health. Site index showed significant correlation with percentage of LBP in CVC1 (p = 0.04) and CVC3 (p = 0.07). Percentage of LBP in CVC3 tended to decrease as soil texture became finer. Poorer site index and coarser soil likely resulted in water stress during periods of drought leading to higher %CVC3 LBP. Based on these results, conversion to longleaf pine should start from LBP stands on coarser soil (or lower site index) at Fort Benning.

Evaluating the effectiveness of aSafeHarborProgram for connecting wildlife populations

AbstractConversion of lands to agriculture and development within remaining natural habitats have fragmented ecosystems and reduced wildlife populations. TheUSFish and Wildlife Service has adopted an incentive‐based conservation strategy known as theSafeHarborProgram (SHP) to reduce the vulnerability of federally protected species located on private properties. In addition to protecting populations, theSHPalso strives to enhance species viability by devising strategies to (re)connect populations among habitat patches. We empirically evaluated the effectiveness of the initial Safe Harbor agreement, developed forRed‐cockadedWoodpeckers (Picoides borealis, hereafterRCW) in the North Carolina Sandhills, in enhancing connectivity for that species. According to our results, breeding territories located on private properties enrolled in theSHPpromoted dispersal ofRCWsand enhanced overall population connectivity relative to otherwise similar territories located on non‐SHPproperties. Moreover, theSHPcreated extensive stepping‐stone corridors throughout the region. Our analysis also showed thatRCWconnectivity will be negatively impacted directly and indirectly by encroaching urban growth. By combining an urban growth model with estimated connectivity, managers and conservation planners can identify which properties critical for connectivity are most threatened by urban encroachment. These results can help conservation planners develop strategic actions on private land based on the species specific movement ability, current landscapes and projected urban growth.

Empirical estimation of dispersal resistance surfaces: a case study with red-cockaded woodpeckers

Persistence of wildlife populations depends on the degree to which landscape features facilitate animal movements between isolated habitat patches. Due to limited data availability, the effect of landscape features on animal dispersal is typically estimated using expert opinion. With sufficient data, however, resistance surfaces can be estimated empirically. After modeling suitable prospecting habitat using an extensive dataset from the federally endangered red-cockaded woodpecker (Picoides borealis), we used data from over 800 prospecting events from 34 radio-tagged birds to identify the best relationship between habitat suitability and resistance surfaces. Our results demonstrated that juvenile female P. borealis prospecting for new territories beyond their natal territories preferred to traverse through forests with tall canopy and minimal midstory vegetation. The non-linear relationship between habitat suitability and resistance surfaces was the most biologically relevant transformation, which in turn identified the specific forest composition that promoted and inhibited prospecting and dispersal behavior. These results corresponded with over 60 % of dispersal events from an independent dataset of short-distance dispersal events. This new understanding of P. borealis prospecting behavior will help to identify areas necessary for maintaining habitat connectivity and to implement effective management strategies. Our approach also provides a framework to not only estimate and evaluate resistance surfaces based on species-specific responses to intervening landscape features, but also addresses an often-neglected step, selecting a biologically relevant function to transform habitat suitability model into a resistance surface.

The Distribution and Habitat ofCentruroides hentzi(Banks) (Scorpiones, Buthidae) in Georgia

Field collections made by the authors in pineland ecosystems in southern Georgia during 2011 significantly expand the previously published range limits of the scorpion Centruroides hentzi in Georgia. We commonly found specimens beneath the exfoliating bark of Pinus palustris (Longleaf Pine) and P. elliottii (Slash Pine) snags, stumps, and logs in sandhills and pine flatwoods habitats, documenting this scorpion from 50 sites in 34 south Georgia counties, and extending the known range of C. hentzi 150 km north (from near Waycross, Ware County, GA) to Statesboro, Bulloch County, GA. Our collections indicate that the species is widespread in pine-dominated uplands throughout much of the lower and middle Coastal Plain of southern Georgia. We comment on the life history, ecology, and habitat requirements of the species based on this survey and the existing literature. In Georgia, C. hentzi is a characteristic associate of Longleaf Pine and Slash Pine ecosystems, is often locally abundant, and is part of an arthropod-vertebrate food web that includes the endangered Picoides borealis (Red-cockaded Woodpecker).

Use of acoustics to quantify and characterize bullet overshot into sensitive wildlife areas

Live-fire training exercises on military installations are known to impact tree health and can potentially affect nesting/foraging habitat and behavior of terrestrial animals, though few studies have attempted to quantify and characterize bullet overshot from military training operations downrange into sensitive wildlife areas. There is concern about the potential impact that downrange military munitions might have on the federally endangered Red-cockaded Woodpecker and its foraging and nesting habitat. Various anecdotal methods have been used in an attempt to document bullet overshot, but none of these methods have been shown to be effective. The objective of this project is to demonstrate that acoustical techniques can accurately and effectively record and characterize live-fire bullet overshot into sensitive wildlife areas downrange of active military ranges. This research is part of a long-term study on Fort Benning, GA to investigate how munitions fire affects Red-cockaded Woodpecker nesting/foraging habitat and nesting behavior, while also investigating the effectiveness of earthen berms at stopping bullets from entering downrange areas. Preliminary results and field protocols will be presented and discussed.

Brown-headed Nuthatch Occupancy in Central Florida and Its Relationship to Forest Type, Forest Structure, and the Presence of Red-cockaded Woodpeckers

Abstract. The Brown-headed Nuthatch (Sitta pusilla) is listed as a species of conservation concern throughout most of its range. Forest conditions that support the imperiled Red-cockaded Woodpecker (Picoides borealis) are thought to provide excellent habitat for the nuthatch, but ambiguity exists because the nuthatch has disappeared from some areas where the woodpecker persists. We studied Brown-headed Nuthatches in two forest types that spanned an environmental gradient in central Florida and also differed in terms of forest structure and the presence of woodpeckers. Sandhill forests had mature timber that supported a large woodpecker population (∼70 territories); flatwood forests were dominated by younger pines and supported no Red-cockaded Woodpeckers. We used repeated surveys incorporating broadcast vocalizations and patch-occupancy analysis to assess variation in nuthatch occupancy and detection in relation to forest type, four structural covariates (snag density, basal area of pines and hardwoods, a...