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I assessed avian communities of Gam bel oak (Quercus gambelii) woodland and surrounding habitats at Camp W. G. Williams State Military Reservation, Utah, during summer of 1993-1998. I used point counts and incidental observations to compile an avian checklist. I observed 100 species, accounting for one third of all birds known from Utah. Overlap in species composition among habitats was considerable, yet each habitat supported a distinct complement of common species. I compared bird species composition, abundance, richness, and diversity before and after fire in burned and unburned Gam bel oak woodland using point counts. I also investigated how similarity of the Gam bel oak avian community to surrounding communities changed after fire. Post-fire changes in individual species abundances reflected a shift from a woodland to a grassland/shrubland community. However, this shift occurred through elimination rather than addition of species, i.e., the post-fire Gambel oak avifauna was a subset of the pre- fire avifauna. Species richness and diversity on burned plots decreased significantly after fi re; unburned plots experienced significant increases in richness and diversity. I also used point counts to evaluate recovery of the Gam bel oak avian community by comparing species composition, abundance, richness, and diversity in different-age burned and unburned Gambel oak woodland. Total abundance, richness, diversity, and similarity to the unburned community increased with post-fire age. I observed significant differences in the abundance of 10 species. Fire did not result in sequential invasion and replacement of bird species assemblages; rather, species found in burned plots were a subset of the avifauna in unburned plots. Return of individual species was related to recovery of preferred nesting and foraging substrates. Over 25% of species found in unburned plots were still absent 11 years post-fire. I conclude that fire had pronounced effects on avian community composition and structure in this habitat. The contention that almost all bird species associated with Gambel oak woodlands are tolerant to fire is not substantiated by the results of this study. Due to the lack of spatial replication in this study, a comparison of avian response to fire in several sites across Gambel oak range would be desirable. |
