You know what they say about location and real estate. Hummingbird nests often appear in clusters, but for years researchers couldn’t figure out what attracted the birds to certain areas. Turned out the answer was, “good neighbors.” Biologist Harold Greeney was doing fieldwork in Arizona in 2007 when he and his team realized that breeding hummingbirds often clustered around hawk nests. By 2009, Greeney and company were able to report that the hummers nesting close to hawks were actually more successful at raising chicks. Now, in a study published last week in Science Advances, they are unveiling research into exactly why that seems to be the case. Hawks don’t prey on hummingbirds or their nests—there’s not enough meal in a hummer to be worth the effort, apparently. (“The hawk by weight is about 190 times the size of a hummingbird, so it’s basically the same reason that if you want to catch a fly, you don’t run after it,” said Greeney.) But not only are hawks...