| If you live almost anywhere in the United States and Mexico, you've probably seen a critter like this handsome fellow. He's a male house finch, a species of small, plump bird with blushing red feathers on its head and chest (the females are decked out in a sensible mottled brown). These birds are ubiquitous around my home in D.C., especially in the springtime. It always makes me happy to spot their bright colors and hear their cheerful, warbling chirps. But the funny thing is, these birds don't belong. They're actually natives of the Southwest, creatures of dry chaparral and the edges of woods. They built their nests in cacti and fed on berries, buds and weed seeds. It seems that humans (those pests!) weren't content to leave the finches in their native habitat. I learned recently from a Twitter thread by writer and naturalist Rosemary Mosco that before the passage of the Migratory Bird Treaty in 1918, people often captured American songbirds for pets. Even after the birds were protected, it seems they weren't always safe. The birds continued to be sold in New York pet shops through the 1940s, and when an inspector was about to come by, the owners would just open their cages and let the birds fly away. But house finches are scrappy creatures, and they made the best of their new environment. By the 1990s, according to Audubon, "they had advanced halfway across the continent, meeting their western kin on the Great Plains." What's the secret to their great success? The house finches are really good at making the most of opportunities provided by humans. Research described earlier this year in the Atlantic suggests that their beaks and even their songs have evolved as a consequence of the birds' increased reliance on seeds that humans provide at bird feeders. Something to think about next time I spot a house finch in my neighborhood! -- Sarah | 
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