Effects of disturbance on birds of conservation concern in Eastern Oregon and Washington
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The effects on birds of forest insects, tree diseases, wildfire, and management strategies designed to improve forest health (e.g., thinning, prescribed burns, road removal, and spraying with pesticides or biological microbial agents) are discussed. Those bird species of concern that occur in forested habitats in eastern Oregon and Washington, USA include the bald eagle (Haliaeetus leucocephalus), peregrine falcon (Falco peregrinus), harlequin duck (Histrionicus histrionicus), upland sandpiper (Bartramia longicauda), northern goshawk (Accipiter gentilis), ferruginous hawk (Buteo regalis), and black rosy finch (Leucosticta arctoa). In addition, seven species of woodpeckers (Picoides albolarvatus, P. arcticus, P. tridactylus, Melanerpes lewis and Dryocopus pileatus) and nuthatches (Sitta pygmaea and S. carolinensis) were considered because of their rare status. Forest disturbances that create dead trees and logs are critical to cavity-nesting birds because the dead trees with their subsequent decay provide nesting and roosting habitat. The insects associated with outbreaks or dead trees provide prey for the woodpeckers and nuthatches. The loss of nest or roost trees as a result of disturbance could be detrimental to bald eagles, goshawks, or ferruginous hawks, while the loss of canopy cover could be detrimental to harlequin ducks and goshawks or to prey of some of the raptors. The more open canopies created by thinning may be beneficial to a species like the black rosy finch, yet detrimental to some woodpeckers due to a decrease in cover. Prescribed burning may be beneficial to those woodpeckers primarily associated with ponderosa pine (Pinus ponderosa) stands and detrimental to other woodpeckers because of the loss of coarse woody debris. Removal of roads is likely to benefit most of these species because of the subsequent decrease in human activity. Recovery plans for bald eagles and peregrine falcons are available for managers to use in managing habitat for these species.