Songbirds really do fly south for the winter.

The article discusses the findings of a study conducted by a team lead by researcher Ben Winger and published in the journal "PNAS" that found that North American songbirds migrate south for the winter. Topics include the family of birds studied, consisting of over 800 species; the team's use of a species distribution timeline; the disproved theory that tropical birds fly north to escape overcrowding; and speculation on the effect global warming will have on migratory patterns.