Yellow Warbler
Dendroica petechia
The female Yellow Warbler in the left photo was in the National Elk Refuge in Jackson, WY on May 28, 2013. The male flying on the right was seen in the Grand Tetons, WY on June 4, 2013, and the enlargement shows the reddish streaks on the breast that are characteristic of the male. (Click on images to see enlarged versions.)