Warm weather withers winterizing birds.

• Position: Audubon Society

Wintering bird populations in Florida, Hawaii, and the Gulf Coast of Texas and Louisiana are declining rapidly, while population increases are strongest in the Northeast, boreal forest, and tundra regions, reveals a study by the National Audubon Society, New York. "Bayesian Hierarchical Modeling is a relatively new technique that allows us to estimate population trends from citizen science data with more certainty than ever before," explains quantitative ecologist Nicole Michel.

"This enables us to confidently identify those bird species most in need of conservation efforts, and understand why some species' populations are declining while others are stable or increasing. Identifying wintering bird population trends is particularly important because climate warming is occurring more rapidly in winter than during the breeding season."

Population trend estimates were generated for 551 species of birds across the U.S. and southern Canada since 1966. In order to identify regions where wintering birds are doing well or poorly, data combined , from 228 species produced cross-species trend estimates for each state, province, and larger regions. Some 68% of species were found to have positive trends, while populations of species that overwinter along the Gulf Coast and in Hawaii declined rapidly.

"By linking population trends with traits...