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Section Contents

Cooperative Forest Ecosystem Research
Validation of Songbird Habitat Models
Primary Researchers: W. Daniel Edge and Dodie Wilson
Interest in neotropical migratory songbirds (NMSB) in forest environments of the western United States has increased because of widespread declines of several species. Currently, forest managers frequently use expert-based models that predict NMSB occurrence in forest stands based on forest type and successional stage. Newer probabilistic models have been developed that predict NMSB occurrence based on structural characteristics of stands that are commonly collected during forest inventories or that can be collected using rapid inventory techniques. However, these models have not been validated, nor is it certain that they can be applied outside the areas in which they were developed. An additional question concerning model validation is related to the intensity of the survey effort required to reliably detect a bird species in a forest stand (Smith and Connors 1986, pages 45-50 in Wildlife 2000).

Fifteen logistic regression habitat-relationship models for forest birds have been developed by Weyerhaeuser biologists. The modeled species are: orange-crowned warbler, Bewick's wren, black-throated gray warbler, black-headed grosbeak, brown creeper, evening grosbeak, gray jay, hairy woodpecker, hermit warbler, red-breasted nuthatch, rufous hummingbird, song sparrow, Steller's jay, warbling vireo, and western tanager. These habitat-association models were developed to provide a basis for habitat assessment and diagnosis. The purpose of this study is to test the efficacy of the models to predict the presence or absence of species given particular habitat characteristics. Three approaches were used to evaluate the models: 1) evaluating the accuracy of prediction, 2) whether there was a significant positive linear relationship between the predicted probability of occurrence and the frequency of occurrence at the stand level, and 3) whether the variable coefficients resulting form our data fell within the confidence intervals of the coefficients in the Weyerhaeuser models.

For additional information about this research study see the 2001 CFER Annual Report. (2.7 MB)

All objectives of this study have been accomplished. A thesis titled "Validating Songbird Habitat Relationship Models" (Wilson 2001) has been completed and is on file at the CFER office.

View the abstract for Wilson 2001 (pdf).


  


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