Agricultural change has influenced birds through changes in food quality or quantity

It has been postulated that a general decline in insect abundance linked with intensification of agriculture may have contributed to farmland bird decline. We analysed insect catch data from a single suction trap run for 27 years in a rural location in Scotland, and showed that insect numbers have changed significantly over time. Measures of bird density were significantly related to insect abundance. These data from a broad suite of species provide support for linked temporal change between farmland birds, invertebrate numbers and agricultural practice in Scotland.

Source:
TIM G. BENTON et al. Journal of Applied Ecology (2002) 39, 673–687 (attached)