This healthy, 1-year-old male offspring of a rose-breasted grosbeak and scarlet tanager is the first-ever documented hybrid of its kind. The two species have such divergent nesting preferences that they have been on independent evolutionary trajectories for at least 10 million years—until now. Credit: Stephen Gosser In June of 2020, Stephen Gosser, a self-described "diehard birder," was out in the woods of Western Pennsylvania when he thought he heard the song of the elusive and strikingly beautiful scarlet tanager. The blood-red bird with black wings and tail is a favorite among birders for both its beauty and rarity, as the...