Some Effects of Avian Predators on the Western Spruce Budworm 1 in North Central Washington

Single-branch exclosures were used to examine the effects of avian predators on Choristoneura occidentalis Freeman in north central Washington. Pupal densities on protected branches were twice as high as on control branches. Comparisons between sites and crown levels revealed that apparent differences in predation may have been influenced by differences in natural budworm densities.