@article{garabedian_moorman_peterson_kilgo_2020, title={Effects of group size and group density on trade-offs in resource selection by a group-territorial central-place foraging woodpecker}, volume={162}, ISSN={["1474-919X"]}, DOI={10.1111/ibi.12733}, abstractNote={Trade‐offs in resource selection by central‐place foragers are driven by the need to balance the benefits of selecting resources against the costs of travel from the central place. For group‐territorial central‐place foraging birds, trade‐offs in resource selection are likely to be complicated by a competitive advantage for larger groups at high group density that may limit accessibility of high‐quality distant resources to small groups. We used the group‐territorial, central‐place foraging Red‐cockaded Woodpecker Leuconotopicus borealis (RCW) as a case study to test predictions that increases in group density lead to differences in foraging distances and resource selection for groups of different sizes. We used GPS tracking and LiDAR‐derived habitat data to model effects of group size on foraging distances and selection for high‐quality pines (≥ 35.6 cm diameter at breast height (dbh)) and lower quality pines (25.4–35.6 cm dbh) by RCW groups across low (n = 14), moderate (n = 10) and high group density (n = 10) conditions. At low and moderate group density, all RCW groups selected distant high‐quality pines in addition to those near the central place because competition for resources was low. In contrast, at high group density, larger groups travelled further to select high‐quality pines, whereas smaller groups selected high‐quality pines only when they were close to the central place and, conversely, were more likely to select lower quality pines at greater distances from the central place. Selection for high‐quality pines only when close to the cavity tree cluster at high group density is important to long‐term fitness of small RCW groups because it allows them to maximize benefits from both territorial defence and selecting high‐quality resources while minimizing costs of competition. These relationships suggest that intraspecific competition at high group density entails substantive costs to smaller groups of territorial central‐place foragers by limiting accessibility of distant high‐quality foraging resources.}, number={2}, journal={IBIS}, author={Garabedian, James E. and Moorman, Christopher E. and Peterson, M. Nils and Kilgo, John C.}, year={2020}, month={Apr}, pages={477–491} }
 @article{garabedian_moorman_peterson_kilgo_2019, title={Neighboring group density is more important than forest stand age to a threatened social woodpecker population}, ISSN={["1903-220X"]}, DOI={10.2981/wlb.00574}, abstractNote={Effective conservation of group-living forest wildlife requires information on how forest age moderates population parameters. Relationships between forest age and demographics can guide long-term management for wildlife populations that are expanding in relatively young second-growth forests in response to ongoing habitat management. We examined how forest age moderates effects of group density on long-term trends in group size and fledgling production in the endangered red-cockaded woodpecker Dryobates borealis (RCW) on the Savannah River Site, SC (SRS). We used 32 years of RCW monitoring data and generalized additive models to: 1) model long-term changes in average RCW group size and fledgling production; and 2) model effects of neighboring group density and neighboring group sizes across a gradient of forest age within 800 m of a group's cavity tree cluster. Average fledgling production oscillated over 2–3 year periods, but longer term evaluation indicated oscillations dampened and average fledgling production slightly decreased over time. Average group size fluctuated abruptly over 2–3 year periods from 1985 to 1994, but longer term evaluation indicated a general increase in group sizes from 1985 to 1994, followed by declines from 1995 to 2007, and a steady increase after 2010. Average fledgling production increased in response to neighboring group density but decreased as neighboring group sizes increased. In contrast, average group sizes increased in response to greater neighboring group density and neighboring group sizes. Stand age did not affect these relationships. Collectively, these results suggest forest age does not directly moderate effects of neighboring group density or group sizes on long-term average group size and fledgling production in the SRS RCW population. Although forest structure has been linked to increased RCW group sizes and productivity, our results suggest that with ongoing habitat management, long-term changes in group size and fledgling production will be driven primarily by group density conditions rather than changing forest age.}, journal={WILDLIFE BIOLOGY}, author={Garabedian, James E. and Moorman, Christopher E. and Peterson, M. Nils and Kilgo, John C.}, year={2019} }
 @article{stevenson_lashley_chitwood_garabedian_swingen_deperno_moorman_2019, title={Resource selection by coyotes (Canis latrans) in a longleaf pine (Pinus palustris) ecosystem: effects of anthropogenic fires and landscape features}, volume={97}, ISSN={0008-4301 1480-3283}, url={http://dx.doi.org/10.1139/cjz-2018-0150}, DOI={10.1139/cjz-2018-0150}, abstractNote={Prescribed fire is used to restore and maintain fire-dependent forest communities. Because fire affects food and cover resources, fire-mediated resource selection has been documented for many wildlife species. The first step in understanding these interactions is to understand resource selection of the predators in a fire-maintained system. We attached GPS radio collars to 27 coyotes (Canis latrans Say, 1823) and examined resource selection relative to fire-maintained vegetation types, years since fire, anthropogenic features that facilitate prescribed burning, and other landscape features likely to affect coyote resource selection. Coyote home ranges were characterized by more open vegetation types and more recently burned forest (i.e., burned 0–1 year prior) than available on the study area. Within their home ranges, coyotes avoided areas close to densely vegetated drainages and paved roads. Coyote selection of more recently burned forest likely was in response to greater prey density or increased ability to detect prey soon after vegetation cover was reduced by fires; similarly, coyotes likely avoided drainages due to decreased hunting efficiency. Coyote resource selection was linked to prescribed fire, suggesting the interaction between fire and coyotes may influence ecosystem function in fire-dependent forests.}, number={2}, journal={Canadian Journal of Zoology}, publisher={Canadian Science Publishing}, author={Stevenson, E.R. and Lashley, M.A. and Chitwood, M.C. and Garabedian, J.E. and Swingen, M.B. and DePerno, C.S. and Moorman, C.E.}, year={2019}, month={Feb}, pages={165–171} }
 @article{garabedian_peterson_moorman_kilgo_2019, title={Using qualitative methods to support recovery of endangered species: The case of red-cockaded woodpecker foraging habitat}, volume={17}, ISSN={2351-9894}, url={http://dx.doi.org/10.1016/J.GECCO.2019.E00553}, DOI={10.1016/j.gecco.2019.e00553}, abstractNote={Meta-analyses are powerful tools for synthesizing wildlife-habitat relationships, but small sample sizes and complex species-habitat relationships often preclude correlative meta-analyses on endangered species. In this study, we demonstrate qualitative comparative analysis (QCA) as a tool that can reliably synthesize habitat-fitness relationships from small sample sizes for species with narrow habitat requirements. We apply QCA to results from a habitat threshold regression tree model and identify habitat thresholds with consistent positive effects on fitness of the federally endangered red-cockaded woodpecker (Dryobates borealis; RCW) on the Savannah River Site, USA. We reformulated regression tree results in a QCA framework to examine the consistency of threshold effects on RCW fledgling production at the individual group level (n = 47). Synthesizing regression tree results with QCA revealed alternative combinations of habitat thresholds that in conjunction with group size consistently led to above-average fledgling production for 41 of 47 (88%) individual RCW groups. Importantly, QCA identified unique combinations of habitat thresholds and group size related to above-average fledgling production that were not retained in the regression tree model due to small sample sizes. Synthesizing a small habitat-fitness dataset using QCA provided a tractable method to identify unique combinations of habitat and group size conditions that are consistently important to individual fitness, but may not be detected by meta-analyses that can be biased by small sample sizes. QCA offers a viable approach for synthesis of habitat-fitness relationships and can be extended to address many complex issues in endangered species recovery when correlative meta-analyses are not possible.}, journal={Global Ecology and Conservation}, publisher={Elsevier BV}, author={Garabedian, James E. and Peterson, M. Nils and Moorman, Christopher E. and Kilgo, John C.}, year={2019}, month={Jan}, pages={e00553} }
 @article{garabedian_moorman_peterson_kilgo_2018, title={Evaluating interactions between space-use sharing and defence under increasing density conditions for the group-territorial Red-cockaded Woodpecker Leuconotopicus borealis}, volume={160}, ISSN={["1474-919X"]}, DOI={10.1111/ibi.12576}, abstractNote={Information about how bird species respond to increasing density conditions through either space-use sharing or increased territoriality, and how those changes affect fitness, is essential for effective conservation planning. We used a case study of endangered Redcockaded Woodpeckers Leuconotopicus borealis (RCW) to address these questions. We documented over 36 000 locations from 44 RCW groups in three density conditions on two sites in South Carolina, USA, between April 2013 and March 2015. The frequency of neighbouring group interactions differed among density conditions and was highest for high-density groups. RCW home-ranges and core-areas were larger under low-density conditions ( xHome-range = 88.4 ha, xCore-area = 21.0 ha) than under medium ( xHome-range = 68.29 ha, xCore-area = 16.6 ha) and high-density ( xHome-range = 76.3 ha, xCore-area = 18.6 ha) conditions. Neighbouring RCWs maintained overlapping homeranges with nearly exclusive core-areas across density conditions, but overlap tended to increase as neighbouring group density increased. Under high-density conditions, homerange overlap correlated inversely with clutch size (b se = 0.19 0.09), nestling production (b se = 0.37 0.09) and fledgling production (b se = 0.34 0.08). Our results indicate that RCWs dedicate more effort to territorial defence under high-density conditions, potentially at the expense of greater foraging efficiency and time allocated to reproduction, as evidenced by reduced fitness. Large home-range overlap indicated limited territoriality farther away from cavity trees, but the existence of exclusive core-areas suggests that RCW groups defend habitat closer to cavity trees. Thiessen partitions used to allocate critical foraging habitat offered comprehensive habitat protection for RCW but appear flawed for spatially explicit habitat assessments because they do not accurately delineate space used by individual RCW groups.}, number={4}, journal={IBIS}, author={Garabedian, James E. and Moorman, Christopher E. and Peterson, M. Nils and Kilgo, John C.}, year={2018}, month={Oct}, pages={816–831} }
 @article{garabedian_moorman_peterson_kilgo_2018, title={Relative importance of social factors, conspecific density, and forest structure on space use by the endangered Red-cockaded Woodpecker: A new consideration for habitat restoration}, volume={120}, ISSN={["1938-5129"]}, DOI={10.1650/condor-17-211.1}, abstractNote={ABSTRACT Understanding how the interplay between social behaviors and habitat structure influences space use is important for conservation of birds in restored habitat. We integrated fine-grained LiDAR-derived habitat data, spatial distribution of cavity trees, and spatially explicit behavioral observations in a multi-scale model to determine the relative importance of conspecific density, intraspecific interactions, and the distribution of cavities on space use by Red-cockaded Woodpeckers (Picoides borealis) on 2 sites in South Carolina, USA. We evaluated candidate models using information theoretic methods. Top scale-specific models included effects of conspecific density and number of cavity tree starts within 200 m of Red-cockaded Woodpecker foraging locations, and effects of the number of intraspecific interactions within 400 m of Red-cockaded Woodpecker foraging locations. The top multi-scale model for 22 of 34 Red-cockaded Woodpecker groups included covariates for the number of groups within 200 m of foraging locations and LiDAR-derived habitat with moderate densities of large pines (Pinus spp.) and minimal hardwood overstory. These results indicate distribution of neighboring groups was the most important predictor of space use once a minimal set of structural habitat thresholds was reached, and that placing recruitment clusters as little as 400 m from foraging partitions of neighboring groups may promote establishment of new breeding groups in unoccupied habitat. The presence of neighboring groups likely provides cues to foraging Red-cockaded Woodpeckers that facilitate prospecting prior to juvenile dispersal and, to a lesser extent, indicates high-quality forage resources. Careful consideration of local distribution of neighboring groups in potential habitat may improve managers' ability to increase Red-cockaded Woodpecker density on restored landscapes and mitigate isolation of Red-cockaded Woodpecker groups, a problem that negatively affects fitness across the species' range.}, number={2}, journal={CONDOR}, author={Garabedian, James E. and Moorman, Christopher E. and Peterson, M. Nils and Kilgo, John C.}, year={2018}, month={May}, pages={305–318} }
 @article{garabedian_moorman_peterson_kilgo_2017, title={Use of LiDAR to define habitat thresholds for forest bird conservation}, volume={399}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2017.05.024}, abstractNote={Quantifying species-habitat relationships provides guidance for establishment of recovery standards for endangered species, but research on forest bird habitat has been limited by availability of fine-grained forest structure data across broad extents. New tools for collection of data on forest bird response to fine-grained forest structure provide opportunities to evaluate habitat thresholds for forest birds. We used LiDAR-derived estimates of habitat attributes and resource selection to evaluate foraging habitat thresholds for recovery of the federally endangered red-cockaded woodpecker (Leuconotopicus borealis; RCW) on the Savannah River Site, South Carolina. First, we generated utilization distributions to define habitat use and availability for 30 RCW groups surveyed over a >4-h period twice per month between April 2013 and March 2015. Next, we used piecewise regression to characterize RCW threshold responses to LiDAR-derived habitat attributes described in the United States Fish and Wildlife Service recovery plan for RCW. Finally, we used resource utilization functions to estimate selection of specific habitat thresholds and used the magnitude of selection to prioritize thresholds for conservation. We identified lower and upper thresholds for densities of pines ≥35.6 cm dbh (22, 65 trees/ha), basal area (BA) of pines ≥25.4 cm dbh (1.4, 2.2 m2/ha), hardwood canopy cover (6, 31%), and BA of hardwoods 7.6–22.9 cm dbh (0.4, 6.07 m2/ha); we identified three thresholds for density of pines 7.6–25.4 cm dbh (56, 341, and 401 trees/ha). Selection rankings prioritized foraging habitat with <6% hardwood canopy cover (β = 0.254, 95% CI = 0.172–0.336), < 1.2 m2/ha BA of hardwoods 7.6–22.9 cm dbh (β = 0.162, 95% CI = 0.050–0.275), ≥1.4 m2/ha BA of pines ≥25.4 cm dbh (β = 0.055, 95% CI = 0.022–0.087), and ≥22 pines ≥35.6 cm dbh/ha (β = 0.015, 95% CI = 0.013–0.042). We identified habitat thresholds corresponding to open canopy structure, moderate densities of large and medium pines, and sparse hardwood midstory trees. Selection ranks prioritized multiple thresholds below USFWS range-wide recovery thresholds, indicating site-specific management goals may be beneficial for RCW conservation. Fine-grained LiDAR-derived habitat data coupled with GPS-derived habitat use can guide forest bird conservation by identifying the full range of structural conditions associated with threshold responses.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Garabedian, James E. and Moorman, Christopher E. and Peterson, M. Nils and Kilgo, John C.}, year={2017}, month={Sep}, pages={24–36} }
 @article{garabedian_mcgaughey_reutebuch_parresol_kilgo_moorman_peterson_2014, title={Quantitative analysis of woodpecker habitat using high-resolution airborne LiDAR estimates of forest structure and composition}, volume={145}, ISSN={0034-4257}, url={http://dx.doi.org/10.1016/J.RSE.2014.01.022}, DOI={10.1016/j.rse.2014.01.022}, abstractNote={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 (10 returns/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.}, journal={Remote Sensing of Environment}, publisher={Elsevier BV}, author={Garabedian, James E. and McGaughey, Robert J. and Reutebuch, Stephen E. and Parresol, Bernard R. and Kilgo, John C. and Moorman, Christopher E. and Peterson, M. Nils}, year={2014}, month={Apr}, pages={68–80} }
 @misc{garabedian_moorman_peterson_kilgo_2014, title={Systematic review of the influence of foraging habitat on red-cockaded woodpecker reproductive success}, volume={20}, ISSN={["1903-220X"]}, DOI={10.2981/wlb.13004}, abstractNote={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.}, number={1}, journal={WILDLIFE BIOLOGY}, author={Garabedian, James E. and Moorman, Christopher E. and Peterson, M. Nils and Kilgo, John C.}, year={2014}, month={Mar}, pages={37–46} }