[Tony Leukering managed a shot of the duller, presumed subvirgatus subspecies of the Nelson's Sparrow at the Meadows, which was present yesterday and the day before. The bird's face/malar area and breast are similar to each other in hue, good for Nelson's, but this bird is duller than the bird pictured below, grayish, and weakly patterned. Click to enlarge.]
If you're confused by this Nelson's Sparrow buisness, by the way, you should be. Nelson's Sparrow used to be called Nelson's Sharp-tailed Sparrow, and, before that, was lumped with Saltmarsh Sharp-tailed Sparrow. Back when the two were considered one, they were called just Sharp-tailed Sparrow. For now anyway there is the Saltmarsh Sparrow and the Nelson's Sparrow.
The skinny on Nelson's Sparrows is that each subspecies breeds in separate areas. Ammodramus nelsoni nelsoni breeds from the southern Northwest Territories and east-central British Columbia south and east through the prairie provinces to the northern Great Plains states in the U.S. A. n. alterus nests along the coasts of Hudson Bay and James Bay, and annoyingly is not illustrated in any of the field guides. A. n. subvirgatus occurs along the St. Lawrence River and along the Atlantic coast from southeastern Quebec and the Maritime Provinces to southern Maine.
All three Nelson's Sparrow subspecies winter along the Atlantic and Gulf coasts from New York to Texas (nelsoni also winter along the Pacific coast). The ones in the meadows are migrants and very unlikely to winter there, since it's freshawater and will freeze. It is possible to dig up Nelson's and Saltmarsh Sparrows in salt marshes in winter, however.