Consumption of jack-pine budworm, Choristoneura pinus Freeman, by the eastern chipping sparrow, Spizella passerina (Bechstein)

Abstract

Predation by the eastern chipping sparrow, Spizella passerina (Bechstein), on the jack-pine budworm, Choristoneura pinus Freeman, was investigated in northern Michigan. Singing-male counts and bird-banding records provided estimates of bird populations, budworm consumption rates were estimated from observation cage results, and budworm populations were estimated from branch sample counts. Average rate of consumption of all life forms of the budworm was 7.8/h per bird and remained nearly the same regardless of the number of life stages of the budworm available. Overall consumption was 3000/acre (7500/ha) for adults, 600/acre (1500/ha) for juveniles, and 300/acre (750/ha) for nestlings over a 22-day feeding period, resulting in 0.92% budworm mortality. Methods of estimating juvenile and nestling consumption of budworm are presented.