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61 result(s) for "Saab, Victoria A."
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Development and evaluation of habitat suitability models for nesting white-headed woodpecker (Dryobates albolarvatus) in burned forest
Salvage logging in burned forests can negatively affect habitat for white-headed woodpeckers (Dryobates albolarvatus), a species of conservation concern, but also meets socioeconomic demands for timber and human safety. Habitat suitability index (HSI) models can inform forest management activities to help meet habitat conservation objectives. Informing post-fire forest management, however, involves model application at new locations as wildfires occur, requiring evaluation of predictive performance across locations. We developed HSI models for white-headed woodpeckers using nest sites from two burned-forest locations in Oregon, the Toolbox (2002) and Canyon Creek (2015) fires. We measured predictive performance by developing one model at each of the two locations and quantifying discrimination of nest from reference sites at two other wildfire locations where the model had not been developed (either Toolbox or Canyon Creek, and the Barry Point Fire [2011]). We developed and evaluated Maxent models based on remotely sensed environmental metrics to support habitat mapping, and weighted logistic regression (WLR) models that combined remotely sensed and field-collected metrics to inform management prescriptions. Both Maxent and WLR models developed either at Canyon Creek or Toolbox performed adequately to inform management when applied at the alternate Toolbox or Canyon Creek location, respectively (area under the receiver-operating-characteristic curve [AUC] range = 0.61-0.72) but poorly when applied at Barry Point (AUC = 0.53-0.57). The final HSI models fitted to Toolbox and Canyon Creek data quantified suitable nesting habitat as severely burned or open sites adjacent to lower severity and closed canopy sites, where foraging presumably occurs. We suggest these models are applicable at locations similar to development locations but not at locations resembling Barry Point, which were characterized by more (pre-fire) canopy openings, larger diameter trees, less ponderosa pine (Pinus ponderosa), and more juniper (Juniperus occidentalis). Considering our results, we recommend caution when applying HSI models developed at individual wildfire locations to inform post-fire management at new locations without first evaluating predictive performance.
Nest-Site Selection and Nest Survival of Lewis's Woodpecker in Aspen Riparian Woodlands
Riparian woodlands of aspen (Populus tremuloides) provide valuable breeding habitat for several cavity-nesting birds. Although anecdotal information for this habitat is available for Lewis's Woodpecker (Melanerpes lewis), no study has previously examined the importance of aspen woodlands to this species' breeding biology. From 2002 to 2004, we monitored 76 Lewis's Woodpecker nests in aspen riparian woodlands of south-central Idaho to describe nest-site characteristics and estimate the nests' survival. We quantified the vegetation at nest sites and randomly selected other sites to determine habitat features important in the species' selection of a nest site. We then related these features, as well as several time-specific covariates, to nest survival. Lewis's Woodpecker selected nest trees that were larger in diameter than random trees and selected nest sites with more trees, fewer woody stems, and less bare ground than random sites. However, nest-site characteristics were not important determinants of nest survival. Rather, nest-initiation date and daily maximum temperature had the strongest influence on nest survival, which was higher for early nesters and increased with increasing daily maximum temperature. Nest survival (74%) and productivity (2.3 fledglings per successful nest) were comparable to values observed for Lewis's Woodpeckers in burned pine forests, suggesting that aspen riparian woodlands also serve as valuable breeding habitat for this species in the Intermountain West.
Forest birds exhibit variable changes in occurrence during a mountain pine beetle epidemic
Recent epidemics of mountain pine beetles (Dendroctonus ponderosae) have fundamentally altered forests of the Intermountain West, impacting management decisions related to fire, logging, and wildlife conservation. We evaluated how a recent mountain pine beetle epidemic influenced the site occupancy of 39 avian species in forests dominated by ponderosa pine (Pinus ponderosa) on the Helena National Forest, Montana. Point count data were collected during the avian breeding seasons (May–July) of 2003–2006 (pre‐epidemic) and 2009–2011 (during‐epidemic). We used a community‐level Bayesian hierarchical model accounting for imperfect detection to obtain occupancy estimates for all detected forest birds. Our model for site occupancy included the annual presence of mountain pine beetles, the proportion of ponderosa pine at sites, the interaction between the two, and a random effect of year. We observed changes in occurrence over the study period for 23 of 39 species, including shifts toward and away from beetle‐killed ponderosa pine. Community turnover increased during the epidemic and then returned quickly to pre‐epidemic levels. Our results illustrate the myriad habitat preferences of the small landbird community and suggest that a mosaic of disturbed conifer, intact live conifer, and adjacent aspen forests will be critical for the persistence of populations of native avifauna in the Intermountain West.
Foraging-Habitat Selection of Black-Backed Woodpeckers in Forest Burns of Southwestern Idaho
We examined foraging-habitat selection of Black-backed Woodpeckers (Picoides arcticus) in burned forests of southwestern Idaho during 2000 and 2002 (6 and 8 years following wildfire). This woodpecker responds positively to large-scale fire disturbances and may be at risk from logging and post-fire management. With 100 radio-locations of four adult males, we used resource-selection probability functions in logistic form in an information-theoretic framework to model the Black-backed Woodpecker's selection of foraging habitat at fine and coarse spatial scales. Fine-scale data included characteristics of the foraging tree (tree level) and local habitat surrounding foraging trees (plot level, 0.04 ha), whereas coarse-scale data (224–778 ha) included patch characteristics within home ranges. Model selection by Akaike's information criterion identified a multi-scale model containing tree- and plot-level covariates, and their interaction, as the best model to characterize foraging trees. The positive effect of interaction between foraging-tree diameter and plot-level tree density suggested that foraging Black-backed Woodpeckers select both patches with dense trees and larger-diameter trees. Fire severity was not important, possibly because of the time since fire and the birds' habit of foraging on recently dead trees in adjacent unburned forests. Salvage logging that retains large-diameter trees in clumped distributions is most likely to provide long-term foraging habitat for Black-backed Woodpeckers in dry coniferous forests of the interior western U.S. Following wildfire, conservation of forest patches containing weakened trees may extend the suitability of habitat for foraging Black-backed Woodpeckers by up to 8 years.
Avian relationships with wildfire at two dry forest locations with different historical fire regimes
Wildfire is a key factor influencing bird community composition in western North American forests. We need to understand species and community responses to wildfire and how responses vary regionally to effectively manage dry conifer forests for maintaining biodiversity. We compared avian relationships with wildfire burn severity between two dry forest locations of Arizona and Idaho. We predicted different responses to wildfire between locations due to regional differences in historical fire regime. We conducted point count surveys for 3 yr following wildfire (Arizona: 1997–1999; Idaho: 2008–2010) and used multispecies hierarchical models to analyze relationships of bird occupancy with burn severity. Consistent with our prediction for mixed‐severity fire regimes characterizing the Idaho location, we observed proportionately more positive species occupancy relationships and, consequently, a positive species richness relationship with burn severity in Idaho. We also observed the opposite pattern in Arizona, which was congruent with our prediction for the low‐severity fire regime characterizing that location. Cavity nesters and aerial insectivores occupied more severely burned sites following wildfire, corresponding with predicted increases in nesting substrate and foraging opportunities for these species. In contrast, canopy‐nesting foliage gleaners and pine seed consumers exhibited negative relationships with burn severity. Our results were consistent with predictions based on species life histories and with patterns from the literature, suggesting generality of observed relationships and locational difference in relationships with wildfire. We therefore suggest that optimal management strategies for maintaining avian diversity could differ regionally. Specifically, intensive fuels management may be ecologically less appropriate for promoting biodiversity in areas such as the Idaho location where mixed‐severity wildfires and dense forest stands were historically more common.
Adapting Research, Management, and Governance to Confront Socioecological Uncertainties in Novel Ecosystems
Wildland research, management, and policy in western democracies have long relied on concepts of equilibrium: succession, sustained yield, stable age or species compositions, fire return intervals, and historical range of variability critically depend on equilibrium assumptions. Not surprisingly, these largely static concepts form the basis for societal expectations, dominant management paradigms, and environmental legislation. Knowledge generation has also assumed high levels of stasis, concentrating on correlational patterns with the expectation that these patterns would be reliably transferrable. Changes in climate, the introduction of large numbers of exotic organisms, and anthropogenic land conversion are leading to unprecedented changes in disturbance regimes and landscape composition. Importantly, these changes are largely non-reversable; once introduced exotic species are seldom eradicated, climates will continue to warm for the foreseeable future, and many types of land conversion cannot be easily undone. Due to their effects on extant infrastructure and expectations for ecosystem services, these changes are, and will be, viewed by western societies as overwhelmingly negative. The continued acceleration of change will generate increasingly novel systems for which the transferability of correlational relationships will prove unreliable. Our abilities to predict system trajectories will therefore necessarily decrease. In this environment, top-down, expert dominated approaches to environmental decision making are unlikely to produce results that meet broader societal expectations. To be successful we need to embrace a more inclusive paradigm of collaborative governance and multiple forms of knowledge for adapting to constant change, including indigenous epistemological systems. By increasing public and stakeholder participation, we can encourage collaborative social learning allowing all parties to more fully understand the complexities and tradeoffs associated with wildland management and the technical limits of models that seek to quantify those tradeoffs. System novelty will necessarily make forecasting more dependent on predictive modeling and will require better models. Data collection should therefore be strongly influenced by model input requirements and validation; research will need to focus on fundamental and causal relationships to a much greater degree than is done currently.
Woodpecker Nest Survival, Density, and a Pine Beetle Outbreak
Mountain pine beetle (Dendroctonus ponderosae) outbreaks in western North American coniferous forests are increasing in size and severity. An understanding of wildlife population responses to pine beetle outbreaks is needed to inform habitat conservation strategies. We monitored 355 nests of 5 woodpecker species during 2 sampling periods, before (2003–2006) and after (2009–2014) the peak of a pine beetle outbreak in dry mixed conifer forest of Montana, USA. Three of 5 woodpecker species represented the beetle-foraging group: American three-toed (Picoides dorsalis), hairy (Dryobates villosus), and downy (D. pubescens) woodpeckers. The other 2 species studied were northern flicker (Colaptes auratus), a foraging and habitat generalist, and red-naped sapsucker (Sphyrapicus nuchalis), a sap forager and bark-gleaning insectivore. We analyzed daily survival rate of nests in relation to pine beetle outbreak (445,000 ha) severity and timing, along with covariates unrelated to the outbreak (temp, nest height, and nest tree diameter). Our results provided stronger evidence for relationships between woodpecker nest survival and the non-outbreak variables than those associated with outbreaks. Our results indicated limited support for nest survival relationships with beetle severity (annual and cumulative pine tree mortality at 0.81-ha and 314-ha scales). Nevertheless, we observed a significant increase in densities of hatched nests for beetle-foraging woodpeckers following the outbreak. Our results suggest that woodpeckers, particularly beetle foragers, respond numerically to pine beetle outbreaks through increased nesting densities more so than functionally via nest survival.
Development and evaluation of habitat suitability models for nesting white-headed woodpecker
Salvage logging in burned forests can negatively affect habitat for white-headed woodpeckers (Dryobates albolarvatus), a species of conservation concern, but also meets socioeconomic demands for timber and human safety. Habitat suitability index (HSI) models can inform forest management activities to help meet habitat conservation objectives. Informing post-fire forest management, however, involves model application at new locations as wildfires occur, requiring evaluation of predictive performance across locations. We developed HSI models for white-headed woodpeckers using nest sites from two burned-forest locations in Oregon, the Toolbox (2002) and Canyon Creek (2015) fires. We measured predictive performance by developing one model at each of the two locations and quantifying discrimination of nest from reference sites at two other wildfire locations where the model had not been developed (either Toolbox or Canyon Creek, and the Barry Point Fire [2011]). We developed and evaluated Maxent models based on remotely sensed environmental metrics to support habitat mapping, and weighted logistic regression (WLR) models that combined remotely sensed and field-collected metrics to inform management prescriptions. Both Maxent and WLR models developed either at Canyon Creek or Toolbox performed adequately to inform management when applied at the alternate Toolbox or Canyon Creek location, respectively (area under the receiver-operating-characteristic curve [AUC] range = 0.61-0.72) but poorly when applied at Barry Point (AUC = 0.53-0.57). The final HSI models fitted to Toolbox and Canyon Creek data quantified suitable nesting habitat as severely burned or open sites adjacent to lower severity and closed canopy sites, where foraging presumably occurs. We suggest these models are applicable at locations similar to development locations but not at locations resembling Barry Point, which were characterized by more (pre-fire) canopy openings, larger diameter trees, less ponderosa pine (Pinus ponderosa), and more juniper (Juniperus occidentalis). Considering our results, we recommend caution when applying HSI models developed at individual wildfire locations to inform post-fire management at new locations without first evaluating predictive performance.
Short-term benefits of prescribed fire to bird communities of dry forests
Background Low-severity prescribed fire is an important tool to manage fire-maintained forests across North America. In dry conifer forests of the western USA, prescribed fire is often used to reduce fuel loads in forests characterized historically by mixed- and low-severity fire regimes. Understanding the ecological effects of prescribed fire treatments is important for predicting the impacts of these management actions on wildlife communities. Few studies, however, have estimated small landbird responses to forest treatments at spatial scales relevant to their ecology or have examined potential differences in treatment effects applied within historically mixed- vs. low-severity fire regimes. Therefore, we evaluated prescribed fire treatment effects and relationships with burn severity for avian communities in dry conifer forests dominated by ponderosa pine ( Pinus ponderosa ) located on seven national forests in the interior western USA. We surveyed birds for 1–4 years and 1–3 years before and after prescribed fire treatments at mixed- and low-severity fire regime locations, respectively, following a before-after, control-impact study design — 8 paired control-treatment units in mixed-severity locations (16 total study units with 320 survey points) and 4 paired control-treatment units in low-severity locations (10 total study units with 278 survey points). Using a Bayesian hierarchical multi-species occupancy model, we investigated responses to prescribed fire treatments by a community of 95 bird species. Results We found statistically supported treatment effects and/or burn severity relationships for 33 species primarily in mixed-severity locations. The data supported positive treatment effects at mixed-severity locations for 9 species (American robin [ Turdus migratorius ], western bluebird [Sialia mexicana], hairy woodpecker [ Dryobates villosus ], black-backed woodpecker [ Picoides arcticus ], American three-toed woodpecker [ Picoides dorsalis ], house wren [ Troglodytes aedon ], dusky flycatcher [ Empidonax oberholseri ], western wood-pewee [ Contopus sordidulus ], gray flycatcher [ Empidonax wrightii ]), whose occupancy was more likely after treatment at the most severely burned units, and a negative effect for one species (ruby-crowned kinglet [ Corthylio calendula ]), whose occupancy was less likely after treatment at the most severely burned units. At low-severity locations, only two species exhibited treatment effects, both negative (red-faced warbler [ Cardellina rubrifrons ] and lark sparrow [ Chondestes grammacus ]). We also found supported occupancy relationships with burn severity post-treatment (i.e., regardless of species distribution before treatment) for 29 species, most of which were consistent with their life histories (e.g., patterns of positive relationships for cavity-nesting, bark insectivores and negative relationships for open-nesting, foliage insectivores). Stronger responses to prescribed fire treatments at mixed-severity locations were unexpected because prescribed fire applications were more similar to historical wildfires characteristic of low-severity fire regimes. Conclusions Bird populations in historically low-severity locations may be relatively unresponsive to prescribed fire because fire there is typically more frequent and regular. By comparison, fire events in forests characterized by a mixed-severity regime are less common, potentially eliciting more responses to an infrequent opportunity, even by species that are strongly associated with recently burned forests by wildfire. Our results suggest that fire management activities intended to reduce fuels and lower the risk of high-severity wildfire can also be effective in creating habitat for some fire specialists at least in the short term.
Prescribed fire limits wildfire severity without altering ecological importance for birds
Background Fire suppression and anthropogenic land use have increased severity of wildfire in western U.S. dry conifer forests. Managers use fuels reduction methods (e.g., prescribed fire) to limit high-severity wildfire and restore ecological function to these fire-adapted forests. Many avian species that evolved in these forests, however, are adapted to conditions created by high-severity wildfire. To fully understand the ecological implications of fuels reduction treatments, we need to understand direct treatment effects and how treatments modulate subsequent wildfire effects on natural communities. We studied bird population and community patterns over nine years at six study units, including unburned (2002–2003), after prescribed fire (2004–2007), and after wildfire (2008–2010). We used a before-after, control-impact (BACI) approach to analyze shifts in species occupancy and richness in treated units following prescribed fire and again in relation to burn severity following wildfire. Results We found examples of both positive and negative effects of wildfire and prescribed fire on bird species occupancy depending on and largely consistent with their life history traits; several woodpecker species, secondary cavity-nesting species, aerial insectivores, and understory species exhibited positive effects, whereas open cup canopy-nesting species and foliage- or bark-gleaning insectivores exhibited negative effects. Wildfire affected more species more consistently through time than did prescribed fire. Wildfire burned units initially treated with prescribed fire less severely than untreated units, but the slopes of wildfire effects on species occupancy were similar regardless of prior prescribed fire treatment. Conclusions Our results suggest managers can employ prescribed fire to reduce wildfire severity without necessarily altering the ecological importance of wildfire to birds (i.e., the identity of species exhibiting negative versus positive responses). Additional study of the ecological implications of various fuels reduction practices, representing a range of intensities and fire regimes, would further inform forest management that includes biodiversity objectives.