Songbird response to wildfire in mixed-conifer forest in south-western Oregon

Abstract. We used 1 year of pre-fire and 4 years of post-fire data to quantify changes in the occurrence of birds at burned and unburned sites in a southern Oregon watershed after a 2500-ha wildfire. Our objectives were to identify bird species that increased or decreased as a result of this mixed-severity fire. Of the 27 species we investigated, we found evidence for fire-induced changes in the proportion of sites occupied by 13 species. Of these, most (8 species) were species that occurred at fewer sites after the fire than before. These changes were consistent with changes in vegetation composition, which included a decrease in the cover of conifer species and an increase in the cover of broadleaf species. To evaluate the effect of the fire on other ecological conditions, we compared the abundance of nest predators and potential prey items (arthropod biomass) between burned and unburned areas in the 3rd and 4th years after the fire. We found little evidence that the abundance of nest predators differed between burned and unburned areas in either year. There was, however, substantial spatial and temporal variation in arthropod abundance. Hemipteran and coleopteran biomass was greater in burned areas in both the 3rd and 4th year after the fire, and overall arthropod biomass was greater in the 4th year after the fire. The spatial and temporal variability in the bird response to this fire illustrates the importance of before–after–control– impact and multi-year studies for understanding the effects of large-scale disturbances on avian community composition