For many years now, many birders have wondered why the Nelson's Sharp-tailed Sparrow is so infrequently encountered in Michigan, despite its annual occurrence in small numbers during fall migration in Ontario, Wisconsin, Illinois, Indiana, and Ohio. I think there's a good chance that they are more common here than we think, and that with some concerted searching that the bird could be found annually in Michigan.
My reasoning for this predilection can be summed up in two other bird species: Yellow Rail and Le Conte's Sparrow. Both migrate through our state in moderate to large numbers, yet the rail is almost never recorded during migration, and the sparrow is seen very infrequently as a migrant. Like Nelson's Sharp-tailed Sparrow, the rail is very secretive, and this certainly is a part of the explanation for its rarity. However, all three species appear to also be highly selective in their use of habitats, occurring in a habitat few birders ever enter: Extensive sedgy, grassy marshes or meadows usually with standing water of 2-10".
My goal in opening this dialogue is to find whether Nelson's Sharp-tailed Sparrow is findable annually during fall migration in Michigan. To begin, please read these posts from 2004 from Allen Chartier and a response from Alan Wormington, for an excellent introduction to the problem. Using this information, I have scouted a handful of areas in west lower Michigan, and have mapped out a few of the places I suspect may support the species; there are certainly more out there. Searching in these areas may require kayaks, rubber boots, and endurance. If you can, try to get a party of searchers together and wander through the habitat watching for birds to flush.
Lastly, this bird still requires documentation by the Michigan Bird Records Committee, so please document any individuals thoroughly. Be sure to separate any bogies from the very similar Le Conte's Sparrow- one good field mark is the color of the median crown stripe- steel gray on Nelson's and whitish/pale yellowish on Le Conte's.