Moving Beyond Niche Models: Habitat Suitability for Nesting White-Headed Woodpeckers

Ecological niche models of habitat suitability are attractive due to their conceptual interpretation and use of presence-only data. Niche models have potential to exploit a variety of presence-only data sources, such as museum records, limited effort surveys, ancillary field observations, and citizen science programs. Limitations of niche models, however, substantially reduce their utility in management situations, in particular, the inability to independently evaluate habitat covariates for their relative influence. Generalized linear models, i.e., logistic regression, provide this ability, but require both presence and absence data. We present an approach that overcomes the limitation of niche models while retaining the use of presence-only data. The generation of pseudo-absences, derived from areas of low suitability as determined by the niche model, allow use of logistic regression to produce robust models of habitat suitability. The approach also has the added benefit of reducing contamination (false absences) among absence data that occurs with simple random sample approaches. We discuss the pseudo-absence approach in an example of modeling habitat suitability for nesting white-headed woodpeckers (Picoides albolarvatus)

Avian Community Changes in Relationto Different Forest Fire Conditions in Central Idaho

Wildfire is an important driver of forest bird communities in western North America. To fully understand wildfire effects, more studies comparing species-specific responses across space, time, and a range of burn severities are needed. We analyzed point count data (n = 809 point × year survey occasions; 2002–2010) from central Idaho to examine forest bird community responses to fire. Using community occupancy models, we analyzed changes in point occupancy before and after prescribed burning and wildfire, and along a post-wildfire burn-severity gradient. Occupancy patterns were largely consistent with those expected from species life histories. Cavity nesters and aerial insectivores (mountain bluebird [Sialia currucoides; n = 37 survey occasions detected], house wren [Troglodytes aedon; n = 15], Olive-sided Flycatcher [Contopus cooperi; n = 15]) responded positively to fire consistent with increases in nesting substrate and foraging opportunities expected for these species. Shrub-nesting species (lazuli bunting [Passerina amoena; n = 75], Black-headed Grosbeak [Pheucticus melanocephalus; n = 29]) exhibited lagged positive responses with the expected lag in shrub development after wildfire. In contrast, canopy-nesting foliage gleaners and pine-seed consumers (Clark’s nutcracker [Nucifraga Columbiana; n = 50], Townsend’s warbler [Setophaga townsendi; n = 133]) responded negatively to wildfire. More species responded positively than negatively to fire, and responses to high-severity wildfire were stronger than to prescribed burning. Consequently, species richness increased by approximately 3 species from low- to high-severity burned points and pre- to post-wildfire years. Our results suggest high-severity wildfires generate important habitat for many species, contributing positively to avian diversity

Avian Community Response To A Recent Mountain Pine Beetle Epidemic

Recent epidemics of mountain pine beetles (Dendroctonus ponderosae) will fundamentally alter forests of the Intermountain West, impacting management decisions related to fire, logging, and wildlife habitat. We evaluated effects of a recent mountain pine beetle epidemic on site occupancy dynamics of > 60 avian species in four study units dominated by ponderosa pine (Pinus ponderosa) in the Helena National Forest. Point count data were collected during the avian breeding seasons (May-Jul) of 2003-2006 (pre-epidemic) and again during 2009-2010 (post-epidemic). We used a Bayesian hierarchical model that accounts for detection probability to obtain occupancy estimates for rare and elusive species as well as common ones. We estimated occupancy and detection for all species with respect to the occurrence of the beetle outbreak, live tree density at fine scale (1 ha), and live tree density at coarse (landscape) scale (100 ha). Preliminary analyses focus on trends in occupancy for species of interest, such as the American Three-toed Woodpecker (Picoides tridactylus), as well as patterns of occupancy for nesting and foraging guilds. Results indicated diverse responses among species, with occupancy rates increasing for some and declining for others

Landscape Heterogeneity at White-Headed Woodpecker Nest Sites in West-Central Idaho

The white-headed woodpecker (Picoides albolarvatus) is a regional endemic species of dry conifer forests in the Inland Pacific Northwest, where forest restoration activities are increasingly common. Recent efforts to mitigate severe fire effects and restore ecological function in these forests have prompted land managers to consider the implications of forest management actions on a range of resources, including wildlife. Identifying the associations of sensitive wildlife species with the structure and distribution of resources across landscapes is necessary for scientifically-sound management decisions. We examined the heterogeneity and proportion of open- and closed- canopy forest patches surrounding white-headed woodpecker nest sites during 2012 and 2013. We used logistic regression to compare differences between nest (n = 34) and non-nest (n = 184) sites. We found a stronger positive relationship with low canopy closure within 1-ha of nest sites compared with non-nest sites (nests: x? = 0.49, SD = 0.43; non-nests: x? = 0.06, SD = 0.16; P < 0.001). We also measured a stronger positive relationship with the edge density between low and moderate canopy patches within a 1-km radius of nest sites compared with non-nest sites (nests: x? = 30.0 meters/ha, SD = 14.6; non-nests: x? = 18.4 m/ha, SD = 14.9; P < 0.001). Our results are consistent with studies of nesting white-headed woodpeckers in Oregon. These data will help further validate and refine habitat suitability models across their northern range and contribute towards effective management decisions that will benefit the white-headed woodpecker

Occupancy Dynamics of Avian Species in Relation to A Mountain Pine Beetle Epidemic

Recent epidemics of mountain pine beetles (Dendroctonus ponderosae) will fundamentally alter Rocky Mountain forests, impacting management decisions related to fire, logging, and wildlife habitat. We evaluated effects of a recent mountain pine beetle epidemic on occupancy dynamics of 46 avian species. Seventy-six point count stations were randomly located in four, 250 ha study units within pine (Pinus spp.) forests in the Elkhorn Mountains, Montana. Each point was visited 3 times during the breeding seasons (May-Jul) 2003-2006 (pre-outbreak) and 2009-2011 (post-outbreak). We used a Bayesian hierarchical model of multi-species occupancy that accounts for imperfect detection and allows for estimates of rare, as well as common species. Occupancy was modeled for all species with respect to preoutbreak years, year since the outbreak, and proportion of ponderosa pine. Results supported our prediction that occupancy rates would increase after the outbreak for bark-drilling woodpeckers (Picoides spp.). Occupancy rates of foliage-gleaning chickadees (Poecile spp.) and bark-gleaning nuthatches (Sitta spp.) declined soon after the peak in beetle-induced tree mortality (2008); however, their rates began to rise within 3 years. Bark-gleaning species’ occupancy relationships with ponderosa pine changed after the outbreak. Our results will help inform forest management activities for the persistence of species that evolved with largescale disturbances

Home-Range Size of White-Headed Woodpeckers in W est- Central Idaho

The white-headed woodpecker (Picoides albolarvatus) is a species of management concern in dry-conifer forests of the Inland Northwest, where forest restoration and fuels reduction treatments are increasingly common.  This species may be vulnerable to forest management treatments because it occupies a limited distribution and has narrow habitat requirements.  Forest treatments could negatively affect this species if foraging and nesting resources are removed or could benefit the species through creation of more heterogeneity across the landscape.  Studies of other woodpecker species have identified resource availability and habitat composition as a key influence on the variation of home range size within a population.  We examined home range size of white-headed woodpeckers in a landscape historically managed for timber harvest and is currently receiving extensive forest restoration treatments.  In our first field season, we obtained relocations on 7 radio-tagged woodpeckers (5 males and 2 females, all from different breeding pairs), from late nesting through fledgling periods (late June to early September).  We obtained direct foraging observations at the radio locations.  Estimated home range sizes were quite variable(24 - 180 ha), based on the minimum convex polygon (MCP) method.  We will also estimate home range sizes using the fixed-kernel method.  Identifying habitat spatial attributes that account for variation in home range size will contribute towards effective management decisions for the persistence of white-headed woodpecker populations

Simulations Inform Design of Regional Occupancy-Based Monitoring for a Sparsely Distributed, Territorial Species

Sparsely distributed species attract management concern. Insufficient information on population trends, however, challenges conservation and funding prioritization. Occupancybased methods are cost effective and therefore attractive for broad-scale trend monitoring, but appropriate sampling design and inference depend on particulars of the study system. We employed spatially explicit simulations to inform regional occupancy-based monitoring of white-headed woodpeckers (Picoides albolvartus), a sparsely distributed, territorial species threatened by habitat decline and degradation. We incorporated basic knowledge of species ecology into population simulations to compare statistical power and trend estimation error under alternative scenarios. Sampling effort needed to achieve adequate power to observe a long-term population trend (? 80% chance to observe a 2% yearly decline over 20 years) consisted of annually monitoring ? 120 transects using the single-survey approach or ? 90 transects using a repeat-survey approach. The single-survey approach, which employs occupancy as an index of abundance and requires auxiliary information to account for detectability, provided more power for a given level of sampling effort than repeat-survey approaches. Alternate allocation schemes improved statistical power and trend estimates over the baseline (surveying 10 points within all transects annually), including surveying a subset (33%) of transects each year (i.e., a panel design) and surveying fewer points per transect in exchange for a larger spatial sample. Considering this case study, single-survey methods (with separate evaluation of detectability), panel designs, and aligning sampling resolution with home range size could likely benefit broad-scale occupancy-based monitoring of other sparsely distributed and mobile species

Ensemble Habitat Suitability Modeling to Guide Conservation of Black-Backed Woodpeckers

Conservation of black-backed woodpecker (Picoides arcticus), a burned-forest specialist, is challenged by the unpredictable availability of suitable habitat. Habitat models calibrated with data from previous wildfires can be used to predict habitat suitability in newly fire-affected areas. Predictive accuracy of habitat models depends on how well statistical relationships reflect actual ecological relationships. We predicted habitat suitability for Black-backed Woodpecker at Montana post-wildfire forests (? 6 years postfire) east of the continental divide using models calibrated with nest location data from wildlfire locations in Idaho, Oregon, and Washington. We developed 6 habitat models, including one partitioned Mahalanobis model, two Maxent models, and 3 weighted logistic regression models with combinations of seven environmental variables describing burn severity, topography, and pre-fire canopy cover. We converted continuous habitat suitability indices (HSIs) into binary predictions (suitable or unsuitable) and combined predictions using and ensemble approach; we compiled the number of models (0–6) predicting locations (30×30-m pixels) as suitable. Habitat models represented different hypotheses regarding true ecological relationships, making inferences from ensemble predictions robust to uncertainties in the form of these relationships. Thirty-five percent of the area burned by eastside Montana wildfires was predicted suitable by either all seven habitat models or none of them (i.e. complete agreement among models). We recommend conservation of areas (e.g., exclusion of post-fire salvage logging) that were consistently predicted suitable by most models, e.g., 32 percent of burned areas predicted suitable by ? 5 models. Additionally, we recommend surveying areas where models disagree to help validate and refine models

A GIS Tool for Applying Habitat Suitability Models to Inform Management (Poster)

Habitat suitability models are used to guide habitat management for species of conservation concern. Models quantify relationships between known species locations and environmental attributes, which are used to identify and map areas most likely to support species of concern. Managers can then restrict human activities with negative impacts on habitat suitability in these areas. Application of habitat suitability models, however, typically requires technical expertise not available to most land managers. We developed a prototype GIS tool that facilitates application of habitat suitability models to guide management of habitat for woodpecker species of conservation concern. The tool operates within an ArcGIS environment, which is readily available to most managers, and will be capable of generating habitat suitability maps for several species of concern (i.e., Black-backed Woodpecker [Picoides arcticus], Three-toed Woodpecker [P. dorsalis], Lewis’s Woodpecker [Melanerpes lewis], and White-headed Woodpeckers [P. albolvartus]). The tool also automates much of the model application process, reducing requisite technical expertise, and making habitat suitability models widely available. The tool will be accompanied by a manual describing implementation and interpretation of resulting habitat suitability maps. The tool will be especially helpful for informing management of post-disturbance forests (i.e. after wildfire and beetle infestations) to identify suitable habitat for disturbance specialists (e.g., Black-backed, Three-toed, and Lewis’s Woodpeckers).  Identification of suitable habitat is necessary to effectively develop management plans that incorporate the needs of habitat specialists in post-disturbance landscapes. Our prototype is currently being tested by U.S. Forest Service biologists