Ornithology and integrated pest management: Red-winged Blackbirds Agelaius phoeniceus and corn
Dolbeer, R. A.
Red‐winged Blackbirds Agelaius phoeniceus, the most abundant bird in North America, annually destroy over 360 000 tonnes of field corn and substantial amounts of sweet corn. This loss, representing <1% of North American corn production, is localized within 8 km of wetlands where Red‐winged Blackbirds roost in late summer. Red‐winged Blackbirds are often initially attracted to corn fields to feed on insect pests during the 2–3 week period between silking and kernel development. An ideal resolution of the conflict between corn farmers and Red‐winged Blackbirds is to couple the birds' beneficial feeding habits in silking‐stage corn with management techniques to reduce subsequent damage to kernels. Once birds switch from feeding on insects to feeding on corn, protective measures to reduce damage are more critical in the early (milk) stages of kernel development than later because the damage potential is much higher at this time. Birds must eat three times more kernels at 20 days after silking than at 40 days in order to receive the same corn biomass. The use of bird‐resistant cultivars of corn, the deployment of frightening devices during the critical damage period, and the provision of alternative feeding sites are important components of an integrated management programme. The goal is to accommodate Red‐winged Blackbirds as a part of the wetland‐agricultural complex in North America.