The relationship between cavity-nesting birds and snags on clearcuts in western Oregon

Abstract

Relationships between cavity-nesting birds (CNB) and density and characteristics of snags were investigated on 13 clearcuts in central coastal Oregon. Species richness and density of CNB were positively ( P<0.05) related to snag density and were still increasing at the maximum snag density evaluated. Cavity-nesting birds selected ( P<0.05) snags taller than 6.4 m and greater than 78–102 cm in diameter, and avoided ( P<0.05) snags less than 28 cm in diameter. Snags of intermediate decay stages were used for nesting more ( P<0.05) than snags of early and advanced stages of decay. Cavity-nesting birds selected snags with more ( P<0.05) bark cover (greater than 11%) than the average cover found on available snags. Individual CNB species exhibited significantly different ( P<0.05) selections for snag height, diameter, hardness and bark cover. To optimize density and richness of CNB, forest managers should provide ≥ 14 snags ha −1 between 28 and 128 cm diameter at breast height (dbh), between 6.4 and 25 m tall, with at least 10% bark cover, and with a majority in hardness stages 3 and 4.