The meadow was dominated by a plant I do not know, nor have knowingly seen in Michigan. It is a knee to thigh high reed, V-shaped in cross section, which created a very thick monoculture. It was tough to walk through and repeatedly snagged my boots nearly tripping me:
There was also a small amount of cattail and other grassy plants, and the dried pond (left) created a large opening. The sparrows seemed to like the thickets right on the edge of the opening, and I flushed a small dark Ammodramus which was almost certainly a Nelson's (it was very windy, and the bird immediately retreated into the thick grass) right here: 
Next, I had the opportunity to visit Mentor Marsh, Ohio (just east of Cleveland) also in mid-October. A large push of sparrows had hit the week before, and lucky birders at this location found 2 Nelson's amongst hundreds of Swamps and Songs with a smattering of Lincoln's, White-throated and White-crowned and other species. This is a small linear patch of grasses and smartweeds along a boardwalk nestled within a huge marsh of Phragmites:
Here is what the habitat along the boardwalk looks like:
And here is what the local smartweed (it appears to be a different species than any I found in Michigan this fall) looks like:
Now, I want to do a satellite imagery overview of sites at which this species is found annually in numbers in the Great Lakes region. First, the sites directly on the shore of Great Lakes:Hillman Marsh, Ontario (the birds are in a wet grassy/weedy unit in the NW corner of the marsh and are found by walking through 2-10 inches of standing water, but are rarely seen from the adjacent dike):
Toronto Islands (birds often reported in apparently inappropriate habitat [sparsely grassy areas on dry soil], but only for a short time [i.e. they do not linger like those at Dundas Marsh])
Northerly Island, Chicago (birds often in grasses at south end)
Montrose Harbor, Chicago (birds in grassy patch [not Marram Grass as in SW Mich] east of marina)
Hammond Bird Sanctuary, near Whiting, IN. Birds are found in thick grassy areas near the back of the beach. Note the industrial nature of the entire surroundings.
Here is a closeup shot of the habitat provided by Byron K. Butler (his copyright)
Lorain harbor, Ohio (birds in round dredge spoil)
Milwaukee, WI Coast Guard Impoundment (birds in square dredge spoil) 
Lastly, the location of Skye Haas's vagrant Nelson's Sparrow (red arrow) from October in Marquette. This site seems to have much in common with the previous sites: small patch of grassy habitat near or on a peninsula on a Great Lake, surrounded by unsuitable habitat (in this case, forest or park).
Summary: It is clear that small peninsulas jutting out into any Great Lake and covered in thick grasses or sedges, and especially those located in areas dominated by a landscape of unsuitable habitat such as pavement (e.g. Montrose, Northerly Id., Lorain harbor) or agricultural fields (e.g. Hillman Marsh) are very good places to look. Let's have a look at the coasts of lower Michigan, starting with Lake Michigan:
It is abundantly clear that we simply do not have any peninsulas here. Also, the dunes we do have are covered primarily in Marram Grass, a species apparently absent or at least not dominant on the west shore of the lake (more information please!) and probably unsuitable for Nelson's Sparrow. The best chance for us in this area might be at Grand Haven's Harbor Island. The breakwall at the rivermouth does "break up" the coastline a bit, and just 1 mile or so inland is an appropriate grassy patch which could attract the species, and has had at least one report to date. Here is the map (red arrow showing the patch):
On to Lake Erie's coast:
There are clearly more peninsulas here, including from south to north, Woodtick peninsula (bottom left), Stony Point (just above center), and Pointe Mouillee (top center). The first two are apparently wooded (Woodtick) and residential (Stony Point), but Pointe Mouillee is a marshy State Game Area with interesting potential. Indeed, Adam Byrne, who regularly surveys the property, has located an appropriate wet grassy field near the west boundary of the property (just east of the Mouillee Creek entrance) which could prove to be one of the state's best strategic spots for Nelson's. This fall he had his first ever Monroe County Le Conte's Sparrow in this exact location. Of course, it may be risky to check after Oct 6, the start of the waterfowl season.Lastly, here is the Lake Huron coast:
The east side of the thumb clearly lacks peninsulas, but Saginaw Bay seems to offer a few possibilities. The islands at Wildfowl Bay (NW tip of thumb) seem appropriate but are covered in cattail, and the adjacent Point Charity is covered in woodland. A very interesting possibility is the Contained Disposal Facility (aka Channel Id or Shelter Id), a dredge spoil on an island off of Bay City:
*If* it turns out that this island is covered in grassy habitats (and is accessible to the public- please post a reply if you know), it may be worth a search next fall. Other possibilities might be Nayanquing Point (not a peninsula, but containing some marshy and grassy units right on Saginaw Bay). Elsewhere, from my limited knowledge, I believe that the majority of the Saginaw Bay coastline is managed for cattail wetland and may be less suitable for Nelson's overall. Certainly, the peninsulas north of Au Gres are mostly forested, not marshy- though again I would like more information on this. One last thought: being that the thumb is so dominated by agricultural fields, if an appropriate field or marsh could be located amongst that landscape it would definitely be worth checking next fall.And now a few inland sites. First, Nine Springs Wastewater Treatment facility in Madison, WI. There is a smartweed thicket in the southeast portion of the unit which apparently is the best spot to watch for Nelson's and from which this video comes. The area is very thick and difficult to walk through (apparently, the more it hurts to walk through [nettles?, thorns/pickers?] and the more seeds you have stuck to your clothes, the better).
This is the Lebanon Business park in Lebanon, Indiana. The birds here (annual, often several in a day) spend most of their time in the Barnyard Grass spp. along the edges of the wet impoundments.
The next two shots are from Pennsylvania's best location for this species during migration: the lower Susquehanna River near Lancaster and Bainbridge. The birds are found on the grassy islands in the middle of the river each October.
So, I end by summarizing my thoughts on these sites, and how it relates to Michigan. First, in the Great Lakes Region, the bird appears to be found in the following categories of sites:1) small, grass-covered peninsulas jutting out into Great Lakes
2) relatively small patches of grasses, sedges, or other forbes amongst landscapes of unsuitable habitat such as metropolitan areas, agricultural fields (i.e. Hillman Marsh), or rivers (i.e. lower Susquehannah)
3) small patches of grassy habitat amongst larger patches of Phragmites or cattail (i.e. Mentor Marsh or Muskegon State Game Area at Lane's Landing (the site of 2 recent May sightings).
Problems with sites searched in Michigan during fall 2007:
1) Hofma Preserve: although apparently suitable, this site is quite large, inland over 2 miles, and full of very tall plants. I believe the few individuals which reach our region may be unlikely to occur here, and those that do will be tough to locate with the large search area and tall vegetation.
2) St. Clair Flats: two things: size and bulrush monoculture. This place is so vast that the few birds which occur there may be very dispersed. Second, the bulrush monoculture we experienced may not be the preferred habitat for those that do arrive. However, if small patches of grassy or sedgy habitat could be located amongst the sea of unsuitable bulrush, this site could be perfect. Moreover, it is located due north of Hillman Marsh Ontario, where Al Wormington has found this bird nearly every fall he has checked it in recent years, so the flats are geographically well-placed as well.
3) Roselle Park: too far inland, grasses too thick. Same problem as Hofma.
So, where to look next fall? At this point, the following sites are the ones I believe the bird most likely to be found:
1) Pointe Mouillee SGA: grassy, wet area just east of the Mouillee Creek entrance (rubber boots required).
2) Bay City Contained Disposal Facility (CDF Island). Access needs to be determined, and would require a boat.3) Harbor Island in Grand Haven. See map above.
Lastly, if you have read through this post, I ask you to post your comments as to what I have wrong, what I have right, and especially any other sites in Michigan which sound like the ones just described. Please use the "comments" link below to leave your thoughts.
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