Hummingbirds and Hurricanes: Calling Colibri

[Tamerlane]

*Originally posted by partly_warmer *

Problem 1: If hummingbirds can double their body weight, why don’t they stock up at the feeder when it’s available, instead of taking a chance, once every hour or so, of happening to come back when there’s nothing left – or that a hostile hummer might catch them?

WAG here - For some it may be counter-productive, at least evolutionarily. Hummingbirds follow several different feeding strategies depending on species - There are trapliners ( low and high reward ), territorial migrants ( including the subset of peripheral foragers ), territory parasites, and year-round territorial residents ( California mostly, I think ) and some strategies might better lend themselves to stocking up at a single source than others. Territorial species have to keep moving to guard their territory. A territorial parasite is shooting to get in and out. etc.

Remember, they mostly haven’t evolved to deal with a never-ending source like a feeder and hummingbirds don’t have very large brains :). They won’t realize the bonanza they have and will continue to maintain a coherent territory with multiple feeding sources, even if the others are rendered irrelevant by the feeder.

Problem 2: Is how much gliding they do so much the issue as how well they can glide? Something that’s airborne with no glide must sustain its altitude constantly, or they fall like a rock. The better the glide ration, proportionately the less effort is taken covering a distance.

Well, that’s the thing. They aren’t built to glide and probably can’t in any real sense. They have one of least efficient ( in terms of energetics ) build of any bird.

• Tamerlane

[Colibri]

*Originally posted by partly_warmer *
Problem 1: If hummingbirds can double their body weight, why don’t they stock up at the feeder when it’s available, instead of taking a chance, once every hour or so, of happening to come back when there’s nothing left – or that a hostile hummer might catch them?

Well, sometimes they do. Often an adult male will defend a feeder all day. Anyway, they only need to double their weight just before flying across the Gulf - otherwise it’s inefficient to carry excess mass around. (Though they put on some excess weight even when migrating over land.) And not all Ruby-throats cross the Gulf, especially heading south.

Hummingbirds need to eat insects too, to get protein and vitamins. When they are not at the feeder, they may be looking for insects.

Originally posted by partly_warmer *
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Problem 2: Is how much gliding they do so much the issue as how well they can glide? Something that’s airborne with no glide must sustain its altitude constantly, or they fall like a rock. The better the glide ration, proportionately the less effort is taken covering a distance.*

As Tamerlane has mentioned, hummingbirds are poorly designed for gliding.

This page goes into some of the considerations for gliding. Gliding/soaring species can have long narrow wings, like albatrosses, used for fast soaring in very windy habitats; or long broad wings, for slow soaring in thermals.

Note at the bottom of the page that hummers are unique in being able to generate lift on both the upstroke and the downstroke. Thus their powered flight is more efficient than any other bird. Because of this, a hummer’s wing beat is actually relatively slow in proportion to its size.

*Originally posted by partly_warmer *
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Problem 3: A bird over land could easily see that it was following a favorable wind. I’m not sure how a bird over the ocean could, but . . . seems like a hummer would if it could. **

Hummers are likely to launch themselves over the ocean only when they have favorable winds. After that, they just have to keep going in the right direction regardless of how the winds may change.