General Discussion

Omaha Steve

(99,845 posts) Thu May 5, 2016, 11:40 PM May 2016

Audubon: Where Do Hummingbirds Get All That Energy?

We had our first Ruby-throated Hummingbird sighting Tuesday. A lone female. We saw a male and female Wednesday.

http://www.audubon.org/news/where-do-hummingbirds-get-all-energy?utm_source=HaH-engagement&utm_medium=email&utm_campaign=2016-05-02-Energy

By Noah Strycker April 13, 2016

Unique among avians, hummingbirds can be thought of as nature’s little hoverboards—except, of course, they don't explode into flames. Their fighter-jet acrobatics are as dazzling as their plumage, and they’re the only birds that can fly sideways and backwards. 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—energetically 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 155,000 calories a day. (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—even at the cost of having a social life.

Unlike many other birds, hummers don’t hang around in flocks (except when they concentrate near food); males and females don’t 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 “leks”—places where males get together to vocalize and show off for females. But even lek mates don’t end up sticking it out for long periods of time.

FULL story at link.