Are avian abundance, diversity, and community composition explained by the same types of predictors?

Background/Question/Methods

Management of landscapes for birds may be based on several different objectives, including achieving particular community composition, manipulating diversity or abundance, and aiding threatened species.  Using a U.S.-wide analysis, we examine whether these disparate characteristics, community composition, diversity or abundance, and conservation value, are influenced by similar underlying predictors.  These predictors include land cover types, vegetation density, fragmentation, climate, topography, and location.

 Results/Conclusions

This suite of predictors accounted for most of the variation present in avian community composition, diversity, and abundance but not in relative abundance of threatened species.  Although climate, land cover classification, vegetation cover, forest fragmentation, topography, and location were significant predictors of the bird community characteristics, the relative importance of these predictors varied according to community characteristic being explained.  Thus, for example, climate was a more important predictor of community composition than of abundance while land cover diversity was an important predictor of species diversity but not of abundance.  These differences illustrate the difficulty of simultaneously achieving disparate mangement goals, such as bolstering threatened species populations while increasing diversity.