Abstract
In this paper, we present an estimate of the predation impact of the global population of insectivorous birds based on 103 (for the most part) published studies of prey consumption (kg ha(-1) season(-1)) of insectivorous birds in seven biome types. By extrapolation-taking into account the global land cover of the various biomes-an estimate of the annual prey consumption of the world's insectivorous birds was obtained. We estimate the prey biomass consumed by the world's insectivorous birds to be somewhere between 400 and 500 million metric tons year(-1), but most likely at the lower end of this range (corresponding to an energy consumption of ≈ 2.7 × 10(18) J year(-1) or ≈ 0.15% of the global terrestrial net primary production). Birds in forests account for > 70% of the global annual prey consumption of insectivorous birds (≥ 300 million tons year(-1)), whereas birds in other biomes (savannas and grasslands, croplands, deserts, and Arctic tundra) are less significant contributors (≥ 100 million tons year(-1)). Especially during the breeding season, when adult birds feed their nestlings protein-rich prey, large numbers of herbivorous insects (i.e., primarily in the orders Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, and Orthoptera) supplemented by spiders are captured. The estimates presented in this paper emphasize the ecological and economic importance of insectivorous birds in suppressing potentially harmful insect pests on a global scale-especially in forested areas.