Density of cavity-nesting bird pairs versus snag density in primarily coniferous forests of the Pacific Northwest. Hollow symbols represent coastal forests; solid symbols are inland forest types. (a) All cavity-nesting species.[○] = [326]; snags >50 cm dbh]; [▲] = [118]; snags >30.5 cm dbh); □ =[327]; snags >48 cm dbh]; [■] = [328]; snags >31 cm dbh]; [◊] = [329]; snags >51 cm dbh); [Δ]= [238]; snags >50 cm dbh]; [●]= [70]; >38 cm dbh); [◆] = [330]; snags >50 cm dbh). Solid line is the fitted Michaelis-Menten relationship of the form cavity nesters per ha with asymptote = 2.42 and half saturation constant = 2.37 [adapted from [233]]. (b) Chestnut-backed chickadee pairs [▲] = [118]; snags >30.5 cm dbh]; [●] = [327]; snags >48 cm dbh]. [○] = [329]; snags >51 cm dbh]; □ = [238]; snags >50 cm dbh]. (c) Mountain chickadee pairs: [▲] = [118]; [■] = [328]; [○] = [70].