You've heard the expression "thin as a rail." There is an entire family of birds known as rails. They can compress their bodies laterally, making themselves thin, slipping silently and quickly out of sight in their wetland homes.

This story is about one of those rails. Well, maybe one of them.

There are six North American members of the rail family. Minnesota has rails, but not the one featured here, the black rail, smallest and least seen in the group.

Rails are almost never seen flying, although in this story the bird flies.

There are some facts here, and much wishful thinking. Wishful thinking is part of birding. Often, it's what gets us out the door.

So, my wife, Jude, and I are driving through Nebraska, on our way home from Thanksgiving dinner. We pass the entrance to the auto tour route on Valentine National Wildlife Refuge (great place!). Take a look? Why not?

Twenty minutes into our tour a small black bird flushes from grass beside the road, flies across the road 10 feet in front of us at eye level, landing among the branches of a small willow clump. We watch the bird, 20 feet away, with binoculars for five minutes.

There are not many small black bird species. Could this be a black rail?

Things in our favor: It is a black bird. It is small. It has a stubby tail, feathers spread and pointed, a black rail tail. It appears to have the requisite short rail wings. It moves smoothly from branch to branch in that willow, as though long toes are grasping. Rails have long grasping toes, although we did not see the feet on this bird. So, that's probably not totally in our favor.

Other things not in our favor: Black rails are not as black as this bird. This bird is small, but maybe not small enough. As I mentioned, rails almost never fly when disturbed. They run. However, they do have wings.

We took a bird checklist from a trailside kiosk in the refuge. Black rail is listed as R, for rare.

The next day I speak by phone with the refuge manager, Juancarlos Giese. He says he doesn't think anyone has ever actually seen a black rail there. It's on the checklist because, he believes, it has been heard. (There should be an asterisk.)

Black rails have a distinctive call. If this rail is on your personal checklist, chances are you heard it. That was my rail experience, before this one. Although it looks like this one doesn't count.

I have ambiguous feelings. We saw the bird fly for a full two seconds. The tail and wings appeared distinctive. Our view of the bird in the bush was somewhat obstructed, so, while we could not say for certain it was a black rail, neither could we give it another name.

There is room for doubt, space only a rail could slide through, but space nonetheless.

As birders sometimes say in situations like this: Hey, it's your list. Call it what you want.

Read Jim Williams' birding blog at startribune.com/wingnut.