Shrinking North American bird population is getting worse faster. Experts blame agriculture, warming

A new study finds North American bird populations keep dropping, and that decline is speeding up for many species. Thursday's study in the journal *Science* finds that nearly half of 261 species show significant losses. More than half of the declining species are losing birds faster than with each year. Researchers say there are billions of fewer birds than in 1987. The study links the strongest overall declines to regions with more warming. It links the faster rate of loss to intensive farming. Starling, crows, grackles and sparrows are shrinking in numbers fastest.