We could tell they were ducks by their shape and the way they were flying. They circled around the house a few times making a very unusual noise. Their beaks were a bright pinkish/red with a brown body. They landed a few times behind the house near the chickens so we were able to get a better look. But they usually landed up on top of a tall dead tree. And would fly away if we got too close.
It turns out that a flock of them have been coming regularly to this area for the last few years and staying at one of Neighbor's ponds.
Here's what one online source had to say about them:
The Black-bellied Whistling-Duck is a boisterous duck with a brilliant pink bill and an unusual, long-legged silhouette. In places like Texas and Louisiana, watch for noisy flocks of these gaudy ducks dropping into fields to forage on seeds, or loafing on golf course ponds. Listen for them, too—these ducks really do have a whistle for their call. Common south of the U.S., Black-bellied Whistling-Ducks occur in several southern states and are expanding northward.You can also read more about them here. You can even click on a link ("rapid peeping" at bottom right) and hear what they sound like.
And here are a couple over at Neighbor's pond.