Studying puffin populations on three Norwegian islands, scientists have uncovered the first evidence to connect a large-scale hybridization to 20th-century warming trends. Yet a serious decline in the birds’ genetic diversity does not bode well for their future.
A bay-breasted warbler weighs about the same as four pennies, but twice a year makes an extraordinary journey. The tiny songbird flies nearly 4,000 miles (6,437 kilometers) between Canada's spruce forests and its wintering grounds in northern South America.