Effects of wildfire on densities of secondary cavity-nesting birds in ponderosa pine forests of northern Arizona

Abstract

Many catastrophic wildfires burned throughout forests in Arizona during the spring and summer of 1996 owing to severely dry conditions. One result of these fires was a loss of preexisting tree cavities for reproduction. In ponderosa pine (Pinus ponderosa) forests most cavities are found in dead trees; therefore, snags are a very important habitat component for cavity-nesting species. Thls study focused on the impacts of wildfire on bird populations within 3 ponderosa pine forests throughout northern Arizona. We present preliminary results from the first bird breeding season following the fires.

We randomly established points throughout areas that represented 3 burn severities: severely burned, moderately burned, and unburned. We conducted fixed-radius point counts and nest searches throughout the breeding season. Secondary cavity-nesters as a group did not show significant differences in relative abundance among 3 categories of fire severity. When analyzed at the species level, however, the wildfires did affect the relative abundance of 2 secondary cavity-nesting species, western bluebirds and mountain chickadees. We found no secondary cavity-nests in severely burned areas, most likely due to the lack of cavities after the fire.

Keywords

Arizona, fire severity, ponderosa pine, secondary cavity-nesters, snags, wildfire

Citation

Dwyer, Jill K.; Block, William M. 2000. Effects of wildfire on densities of secondary cavity-nesting birds in ponderosa pine forests of northern Arizona. In: Moser, W. Keith; Moser, Cynthia E., eds. Fire and forest ecology: innovative silviculture and vegetation management. Tall Timbers Fire Ecology Conference Proceedings, No. 21. Tallahassee, FL: Tall Timbers Research Station: 151-156