When you're tiny, it's good to have big friends in high places. Living in the shadow of hawks means hummingbirds can protect their eggs and chicks from being eaten by voracious jays. "The jays are food for the hawks, and the hummingbird eggs are just too small and take too long for a predator like a hawk to find," says Harold Greeney at the Yanayacu Biological Station in Cosanga, Ecuador. Greeney's team studied the birds in the Chiricahua mountains of Arizona over three years and found that jays avoided raiding hummingbird nests found in each conical zone fanning out from the 12 hawk nests on treetops they observed. This, they say, is because of the way hawks hunt, swooping on prey including jays from higher up. This effectively envelops the hummingbird nests in a cone-shaped force field avoided by the jays. However, when hawks abandoned their nests following raids by coatis, tree-climbing raccoon-like mammals, the jays became much bolder. They visited what had been no-fly zones and took more hummingbird eggs and chicks than when the hawks were around (Science Advances, doi.org/7hn).
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