Wilson's Warbler
Cardellina pusilla
The Wilson's Warbler largely migrates through the contiguous United States as it alternates between its northern breeding grounds in Canada and Alaska, and its wintering areas of southern Mexico and Central America. However, a small part of its population also breeds along the U.S. west coast, including the San Francisco Bay Area. The left photograph shows a singing male adult Wilson's Warbler, taken in Tilden Regional Park, CA on April 14, 2017. The right photograph shows a juvenile Wilson's Warbler, taken by the San Pablo Reservoir, CA on June 27, 2017. (Click on images to see enlarged versions.)