Unique among avians, hummingbirds can be thought of as nature鈥檚 little hoverboards鈥攅xcept, of course, they don't explode into flames. Their fighter-jet acrobatics are as dazzling as their plumage, and they鈥檙e the only birds that can . But the same physics that sets them apart also exacts a hefty price.
As the world's smallest birds, hummingbirds have a high surface-area-to-volume ratio. That means they lose a lot of heat through their skin (the same way, for example, small ice cubes melt faster than big ones). The problem is compounded by a lack of downy feathers, the fluffy insulation that keeps most birds warm. Skipping the down shaves weight, but the birds must compensate by refueling constantly, consuming two or three times their body weight every day.
That's why hummingbirds love nectar鈥攅nergetically speaking, it's like rocket fuel. They will visit multiple flowers in a minute, lapping up three to seven calories daily. That may seem like a trivial amount, but when scaled to the size of a human, it translates to about . (If the birds were any smaller, it would be physically impossible for them to eat enough to stay alive.) As a result, hummingbirds are territorial. They stake out flowers and feeders, defending a food source at all costs鈥攅ven at the cost of having a social life.
Unlike many other birds, hummers don鈥檛 hang around in flocks (except when they concentrate near food); males and females don鈥檛 even raise their families together. Mating takes about half a second, after which the female zooms off to build a nest, lay eggs, incubate them, and raise the chicks by herself. The only exception to this rule occurs in the tropics, where several species of hummingbirds display at 鈥渓eks鈥濃攑laces where males get together to vocalize and show off for females. But even lek mates don鈥檛 end up sticking it out for long periods of time.
Because hummingbirds have such high metabolisms, even sleep could prove fatal. Going for several hours without refueling could cause them to starve. Luckily, the birds have evolved an extreme solution: At night they enter a state of controlled hypothermia, slowing their breathing and heart rate and drastically lowering their body temperature to save energy. On a particularly frigid night, a hummingbird鈥檚 metabolism can drop by as much as 95 percent.
Because the birds have few natural predators, life expectancy is mostly determined by their own intense biology. As far as we know, hummers age about 10 times faster than humans. They seem to have a high rate of heart attacks, ruptures, and strokes鈥攏ot all that surprising given the fast pace of their lifestyle (up to , to be exact). If a hummingbird slows down, it dies; its existence leaves no room for laziness. So in the end, these birds essentially blow themselves out.