How much is an evening grosbeak worth.

Abstract

Birds consume large numbers of the western spruce budworm Choristoneura occidentalis, a forest insect which defoliates economically valuable stands. The economic value of bird predation on 2 stands in north-central Washington was estimated by substituting the cost to spray with insecticides to produce the same mortality rate as birds cause. It would cost at least $1820 km-2yr-1 over a 100-yr rotation. This figure may be used to appraise the value of individual predator species, such as the voracious evening grosbeak Hesperiphona vespertina, to evaluate the cost-effectiveness of biological control with birds, and to assess silvicultural treatments and other practices which affect both bird and insect numbers.-Authors