Nest-site characteristics and reproductive success of long-eared owls in southwestern Idaho

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In 1980 and 1981, I determined the outcome of 112 nesting attempts by 104 pairs of Long-eared Owls (Asia otus) in the Snake River Birds of Prey Area in southwestern Idaho. All nests were in trees in stick nests built by corvids. Owls used nests in clumps of trees and avoided nests in solitary trees and single rows of trees. Discriminant function analysis revealed that nests selected by owls tended to be wider than unused nests. Nesting success was 34% in 1980 and 51% in 1981. The minimum number of young fledged per successful nest was 3.4 in 1980 and 4.0 in 1981. Predators, probably raccoons (Procyon lotor), caused most nesting failures. Unsuccessful nests tended to be closer to water than were successful nests. Young owls left the nest about 2 weeks before they could fly and "branched" in the tree canopy surrounding the nest. "Branchers" had high survival, and branching may reduce nest predation. The number of nesting pairs in the study area declined 35% from 1980 to 1981. Nesting sites were more likely to have been reoccupied in 1981 if they had been successful in 1980.

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Reference Code: A86MAR01IDUS

Full Citation: Marks, J. S. 1986. Nest-site characteristics and reproductive success of long-eared owls in southwestern Idaho. Wilson Bulletin 98(4): 547-560.

Location: ANIMAL EF: BIRDS