Crazy Maisie Weird Broody Behavior?

[hazy d]

We have two Muscovy ducks, no drake. We got them about a month ago, along with four chickens. All have been happily sharing a coop, until about a week ago. Maisie, one of the ducks, began stalking one of the chickens, a beautiful young black Australorp. She's the biggest of the hens we got, so it's kind of weird to tell what's going on. Anyhow, the ducks have been laying eggs since we got them, usually one a day apiece. But last week around the same time as she started stalking Myrtle (the chicken), she also started acting super broody - feathering her nest box, sitting on imaginary eggs for hours of the day rather than coming out to play. Now this behavior has infected Hazel, our other duck. But the weirdest part is what they do to poor Myrtle.

Usually, Maisie starts it. She gets down low as if she's on a bug hunt, but her wings lift in almost an arrow off her back. She races after Myrtle, with Myrtle clucking and trying to escape all the while. When Maisie catches Myrtle, she puts her foot on top of her to hold her down, and then... she cleans her. She starts to like, preen her. Now, sometimes, Maisie and Hazel double-team poor Myrtle, and then the both get at her, but Hazel is a little rough on her.

There are some sores on Myrtle's legs, fresh, like from this morning.. And they have pulled one or two feathers out of her (I suspect Hazel is the culprit) and from my little bantam hen, too. What is going on? Is it just henpecking? Can I stop it? Should I be worried?