Effects of temperate agriculture on neotropical migrant landbirds

Abstract

The ecology of Neotropical migrant landbirds in temperate farmland is reviewed to develop management recommendations for the conservation of migrants. Migrants constitute about 71% of bird species using farmland and 86% of bird species nesting there. The number and abundances of Neotropical migrants using farmland are greatest in uncultivated edges with trees and shrubless in uncultivated, grassed areas (grassed fencerows, waterways, terrace berms, road verges, and land set aside in the Conservation Reserve Program); and least in rowcrops. Causes of recent declines in abundance of farmland migrants are not clear, but recent decades also saw increasing agricultural mechanization and chemical use that probably lowered breeding productivity of migrants. Major nesting losses of migrants in farmland are from predation, agricultural field operations, and brood parasitism by Brown-headed Cowbirds (Molothrus ater), but few migrants in farmland have been studied. Farmland also has become more homogeneous as farm size increased, uncultivated areas have been removed, and farms have specialized on one or a few commodities. These changes probably have created farmland that often lacks the food, shelter, safe nesting sites, or appropriate interspersion of these needed to attract and sustain Neotropical migrants. Agricultural practices that promote breeding productivity and survival of Neotropical migrants include reduced tillage and inorganic fertilizer inputs and use of integrated pest management programs. The importance of farmland heterogeneity and uncultivated areas with shrubs and trees for enhancing populations of Neotropical migrants is emphasized.

Parent Publication

• Status and management of neotropical migratory birds

Citation

Rodenhouse, Nicholas L.; Best, Louis B.; O''Connor, Raymond J.; Bollinger, Eric K. 1993. Effects of temperate agriculture on neotropical migrant landbirds. In: Finch, Deborah M.; Stangel, Peter W. (eds.). Status and management of neotropical migratory birds: September 21-25, 1992, Estes Park, Colorado. Gen. Tech. Rep. RM-229. Fort Collins, Colo.: Rocky Mountain Forest and Range Experiment Station, U.S. Dept. of Agriculture, Forest Service: 280-295