Red-Breasted Nuthatches Detect Early Increases in Spruce Budworm Populations

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Abstract Early suppression of increasing spruce budworm populations is essential to prevent epidemics; however, early changes in budworm numbers are difficult to detect. An effective and inexpensive method to detect early increases is needed. Red-breasted nuthatches eat more spruce budworm larvae and pupae as the insect increases in number. We estimated the number of large larvae in Maine and northern New Hampshire forest stands in 1982 and 1983 by determining the number of these larvae in the birds' stomachs. When the mean number of spruce budworm in the stomach approached 1.7, budworm populations were nearing high density and could be expected to cause severe defoliation the following year. North. J. Appl. For. 7:81-83, June 1990.