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Turns out these airborne jewels are as tough as diamonds.
In cold weather, hummingbird bodies enter into an "energy-conservation mode called torpor," according to Oregon State ecologist Adam Hadley. Birds that stay north for the winter experience a nightly "mini-hibernation," in which their 107-degree body temperatures can plummet to 48 degrees.
Heart rates also slow during torpor: The blue-throated hummingbird’s heart rate, for instance, drops from 1,260 beats per minute to 50 to 180 beats.