Do birds tack?
Feb. 5th, 2007 12:57 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
jackThis came up the other day and I realised I didn't know. Do birds tack into the wind as boats do? I assumed not because:
* I couldn't see why it would help. A boat tacks because a keel at an angle into the wind can grip the water and have the wind push it sideways, but into the wind. A bird doesn't. If the wind were completely steady the bird would be just like in still air but being translated. I think if a bird wants to go into the wind it's going to have to flap.
* That's not how I've seen birds. They wheel about, but generally when flocking, I assume to coordinate and to evade predators; they don't seem to zigzag.
* No-one ever said they do and I couldn't find any citation
But I thought I should check. Do you know?
* I couldn't see why it would help. A boat tacks because a keel at an angle into the wind can grip the water and have the wind push it sideways, but into the wind. A bird doesn't. If the wind were completely steady the bird would be just like in still air but being translated. I think if a bird wants to go into the wind it's going to have to flap.
* That's not how I've seen birds. They wheel about, but generally when flocking, I assume to coordinate and to evade predators; they don't seem to zigzag.
* No-one ever said they do and I couldn't find any citation
But I thought I should check. Do you know?