somebody has to do it!

From what i remember, it has to do with the noise of flowing water. Bevers find the sound annoying and will cover it until it stops.

I remember a study where they played river noises from a speaker and the bevers covered the speakers with sticks -- even in the absence of any water.

I'm not sure if this means that they are annoyed or if they use it as an indicator that there is something to do.
- Should be simple enough: check their cortisol levels in the presence and absence of various water stimuli.
- Super fair point, I'm projecting human emotions onto the beavers & don't actually know how they feel about the sound of running water lol
- It can be both.

Well, dam

Bopper kurva

Can't you just play the sound of running water and trigger their instinct? I feel like I read that sometime in the last few years.

Actually, I don't even know that you have to do that much I've seen videos of beavers in captivity seemingly trying to build a dam on dry land
- I wonder if there's some kind of near-surface pipes they might hear water running through.
Did you possibly read it in the comment immediately above yours which was posted 1 minute prior to yours, and then attribute it to an ancient memory?
- My mom once told me "if you don't have anything nice to say, don't say anything at all" so I'm going to end my comment right here.
- Naw, we posted at the same time. When I typed my comment (the one i assume you're refering to) there were no comments. Once I hit post this one was already here.
  
  Great minds think alike or something like that lol

"Well dam" - beavers

Some fun reading on why https://gsas.harvard.edu/news/dammed-if-they-do edit: https://www.livescience.com/why-beavers-build-dams

It goes into the how but did they explain the why? Maybe I missed it somewhere

Edit: they're just really particular about the way their water flows
- Sorry I had a few tabs open, this ones a little more informative as to why https://www.livescience.com/why-beavers-build-dams
That awesome! Thanks for the article great read.
"Beavers are 40-to-80-pound [18-to-36 kilogram] smelly bags of meat with really short legs"
- They hate us, cause they aint us

Yes, that's likely the inspiration for this copycat.

So, how does one cross post to another community/instance? I feel as though this could fit in with the beaver community on lemmy(dot)world, but I have absolutely no clue how to cross post.

You should have an option to crosspost it somewhere on the post. Or you could simply copy the direct image link and make a new post using that. Lemmy recognises crossposts by checking if the link is the same. For example if 2 unrelated users make 2 different posts with the same article it will count as a crosspost.

Do they actually dam everything or just build a nest?

The lodge is generally in the middle of the flooded area after they dam it or on the shore in a burrow with the entrance under water deep enough that ice won't freeze if shut if there's not enough water. They don't tend to live in the dam itself. They use all the water to protect themselves.
It should be noted that, aside from petty human concerns like flooded roads and properties, beavers are much better at controlling flooding and generally protecting ecologies than humans.
Saw a thing once, maybe Mythbusters, that showed how beavers are attracted to the sound of running water and want to stop it. In the show, they got the beaver to dam a speaker by playing river/stream noises through it.

Behold wonders of the Beaver Deceiver!

https://beaverdeceivers.com/

Beavers: the Nestlé of the animal world.