The SO was saying that the hummingbirds here are huge compared to what she’s used to. Given that hummingbirds flap their wings very quickly, and that force increases with size, what is the maximum size a hummingbird can theoretically be? How big is the largest extant hummingbird?
The largest hummingbird, aptly enough, is the Giant Hummingbird of the Andes of South America. They weigh a bit less than a House Sparrow, but in body dimensions are closer to a Starling (because they are lightly built).
Because they get power on both the up and the down stroke (unlike most birds), hummers actually beat their wings more slowly than a non-hummingbird of equivalent weight. I would say the limitations on size are not so much structural as ecological, since a larger hummingbird would need flowers that produce more and richer nectar.
This does not appear to be the case. Now I have to think: Hummingbird wings beat very quickly, so fast that they buzz. Other birds’ wings don’t beat visibly as fast, nor do they buzz. So what is the weight of a hummingbird vs. Bird X? If Bird X weighs the same as a hummingbird, how fast do its wings beat? Is the speed of hummingbird wings an illusion caused by their small size and the sound they make?
I have seen a Loggerhead Shrike hover in air for more than five seconds, holding stationary a few feet above the ground, with rapid wind-beats maintaining position. It’s not something the bird evolved to do for a prolonged hover, but proves that it is aerodynamically possible for a bird of maybe twice the body weight of the giant hummingbird. Shrikes are a large genus with similar feeding habits, so I assume most can do it.
It can be seen if you slow the speed down enough. In this videoof a Rubythroat, you can see how the wings actually make a figure eight movement and virtually “flip over” in hovering flight. (Best seen when the bird is at the feeder about 3/4 of the way through.) Hummingbirds have a unique shoulder joint that gives them a far greater range of wing movement than other birds.
The apparent speed of the hummingbird’s wings is due to its very small size. The smaller the bird, the faster it beats its wings. But proportionate to its size, a hummingbirds wings beat slower than other birds. Here’s a video of a Giant Hummingbird in flight. You can see how slow the wings beat relative to a smaller hummer.
Very cool. Are they larger in size as an adaptation to the colder climate?
I don’t think so. There are many species of smaller hummingbirds that occur at the same altitudes, and it’s not the species with the highest altitudinal range. The Ecuadorian Hillstar occurs up to 17,000 ft/5,300 m.
Hummingbirds are most diverse at mid to high elevations rather than in hot tropical lowlands. In cooler temperatures they have a competitive edge over bees and other insects since they are warm-blooded.