Prescribed fire is a management tool used to reduce fuel loads on public lands in forested areas in the western United States. Identifying the impacts of prescribed fire on bird communities in ponderosa pine (Pinus ponderosa) forests is necessary for providing land management agencies with information regarding the effects of fuel reduction on sensitive, threatened, and migratory bird species. Recent developments in occupancy modeling have established a framework for quantifying the impacts of management practices on wildlife community dynamics. We describe a Bayesian hierarchical model of multi-species occupancy accounting for detection probability, and we demonstrate the model's usefulness for identifying effects of habitat disturbances on wildlife communities. Advantages to using the model include the ability to estimate the effects of environmental impacts on rare or elusive species, the intuitive nature of the modeling, the incorporation of detection probability, the estimation of parameter uncertainty, the flexibility of the model to suit a variety of experimental designs, and the composite estimate of the response that applies to the collection of observed species as opposed to merely a small subset of common species. Our modeling of the impacts of prescribed fire on avian communities in a ponderosa pine forest in Washington indicate that prescribed fire treatments result in increased occupancy rates for several bark-insectivore, cavity-nesting species including a management species of interest, Black-backed Woodpeckers (Picoides arcticus). Three aerial insectivore species, and the ground insectivore, American Robin (Turdus migratorius), also responded positively to prescribed fire, whereas three foliage insectivores and two seed specialists, Clark's Nutcracker (Nucifraga columbiana) and the Pine Siskin (Carduelis pinus), declined following treatments. Land management agencies interested in determining the effects of habitat manipulations on wildlife communities can use these methods to provide guidance for future management activities.
We conducted a regional-scale evaluation of landscape permeability for large carnivores in Washington and adjacent portions of British Columbia and Idaho. We developed geographic information system based landscape permeability models for wolves (Canis lupus), wolverine (Gulo gulo), lynx (Lynx canadensis), and grizzly bear (Ursus arctos).We also developed a general large carnivore model to provide a single generalization of the predominant landscape patterns for the four focal species. The models evaluated land cover type, road density, human population density, elevation, and slope to provide an estimate of landscape permeability. We identified five concentrations of large carnivore habitat between which we evaluated landscape permeability. The habitat concentration areas were the southern Cascade Range, the north-central Cascade Range, the Coast Range, the Kettle-Monashee Ranges, and the Selkirk-Columbia Mountains. We evaluated landscape permeability in fracture zones between these areas, including the I-90 Snoqualmie Pass area, the Fraser-Coquihalla area, the Okanogan Valley, and the upper Columbia and Pend Oreille River valleys. We identified the portions of the Washington state highway system that passed through habitat linkages between the habitat concentration areas and areas accessible to the focal species. This analysis provides a consistent measure of estimated landscape permeability across the analysis area, which can be used to develop conservation strategies, contribute to future field survey efforts, and help identify management priorities for the focal species.Keywords: Washington, corridors, fragmentation, habitat connectivity, landscape permeability, endangered species, reserve design.Loss of habitat, isolation of small populations, and direct mortality from collisions with motor vehicles are major concerns in the conservation of large carnivores. To assist in addressing these issues in conservation planning, we conducted a systematic assessment of expected regional-scale landscape permeability for sensitive large carnivores in Washington and adjacent portions of British Columbia and Idaho. Major highways are important landscape features that influence patterns of human activities and can function as partial or complete barriers to large carnivore movement. Our analysis places particular emphasis on identifying areas where the Washington state highway system intersects potential large carnivore habitat and linkages between blocks of habitat.Focal species for this analysis were gray wolf (Canis lupus), lynx (Lynx canadensis), grizzly bear (Ursus arctos), and wolverine (Gulo gulo). We developed geographic information system (GIS) models to evaluate landscape permeability based on broad landscape characteristics that are likely to influence movement patterns for each of the focal species. We also developed a general large carnivore model to evaluate landscape permeability between areas of conservation concern (e.g., large roadless areas or areas identified in large carnivore recovery plans).We used ...
We studied northern flying squirrel (Glaucomys sabrinus) demography in the eastern Washington Cascade Range to test hypotheses about regional and local abundance patterns and to inform managers of the possible effects of fire and fuels management on flying squirrels. We quantified habitat characteristics and squirrel density, population trends, and demography in three typical forest cover types over a four-year period. We had 2034 captures of flying squirrels over 41 000 trap nights from 1997 through 2000 and marked 879 squirrels for mark-recapture population analysis. Ponderosa pine (Pinus ponderosa) forest appeared to be poorer habitat for flying squirrels than young or mature mixed-conifer forest. About 35% fewer individuals were captured in open pine forest than in dry mixed-conifer Douglas-fir (Pseudotsuga menziesii) and grand fir (Abies grandis) forests. Home ranges were 85% larger in pine forest (4.6 ha) than in mixed-conifer forests (2.5 ha). Similarly, population density (Huggins estimator) in ponderosa pine forest was half (1.1 squirrels/ha) that of mixed-conifer forest (2.2 squirrels/ha). Tree canopy cover was the single best correlate of squirrel density (r = 0.77), with an apparent threshold of 55% canopy cover separating stands with low- from high-density populations. Pradel estimates of annual recruitment were lower in open pine (0.28) than in young (0.35) and mature (0.37) forest. High recruitment was most strongly associated with high understory plant species richness and truffle biomass. Annual survival rates ranged from 45% to 59% and did not vary among cover types. Survival was most strongly associated with understory species richness and forage lichen biomass. Maximum snow depth had a strong negative effect on survival. Rate of per capita increase showed a density-dependent response. Thinning and prescribed burning in ponderosa pine and dry mixed conifer forests to restore stable fire regimes and forest structure might reduce flying squirrel densities at stand levels by reducing forest canopy, woody debris, and the diversity or biomass of understory plants, truffles, and lichens. Those impacts might be ameliorated by patchy harvesting and the retention of large trees, woody debris, and mistletoe brooms. Negative stand-level impacts would be traded for increased resistance and resilience of dry-forest landscapes to now-common, large-scale stand replacement fires.
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