The Evidence
Based on taxonomically diverse community in eastern U.S.
- Decline of migrants equal to ~ 1% / year.
Based on wood warblers, vireos, gnatcatchers, kinglets, titmice, chickadees, nuthatches, brown creeper, wrens, bluebirds across U.S.
- No decline for migrants
- Recent declines in birds with high susceptibility to predation / cowbird parasitism