According to Science Advances, many hummingbirds are clever enough to build their nests near that of a neighboring hawk. Researchers from the U.S., Canada, and Ecuador worked together to observe the tiny birds' behavior, and found that those who built their nests near hawks' nests, had a greater survival rate than those who didn't. The researchers believe this is because the hawks provided protection for the hummingbirds against their predators, yet the hummingbirds are small enough to go undetected by the hawks.