I ran a weekly bird survey during the summers of 2001 through 2007 at the Voice of America Park in West Chester, Butler County, Ohio. The grassland birds that breed annually and reliably at the VOA are Savannah Sparrow, Bobolink, and Eastern Meadowlark. Sedge Wrens are irregular, occasional nesters/visitors, usually arriving at the site in early July. However, they haven't been found at the park (to my knowledge) since 2005.
Henslow's Sparrows bred at the VOA from 2002 through 2007, seemingly skipped 2008, but returned sometime in the summer of 2009. Kelly Riccetti photographed adult Henslow's Sparrows at the VOA recently during a trip she chronicled on her blog.
During my surveys, I occasionally found hatch-year Henslow's Sparrows. Here is a "digiscoped" photo of one taken on July 25, 2004:
Here is a photo of a hatch-year Henslow's Sparrow taken on July 11, 2004, two weeks prior to the bird in the above photo:
Adult Henslow's Sparrows are generally easy to identify. Here's another digiscoped photo of an adult taken on July 11, 2004:
This bird is rather worn, and by mid-July, most Henslow's Sparrows are sporting clearly worn-out feathers: bleached, abraded, and frayed. On July 25, 2004, a friend and I had the good luck to see an adult Henslow's Sparrow in the midst of molting. By itself, this would have been a very confusing bird. But on this day, it was with other obviously adult Henslow's Sparrows, and the hatch-year bird in the photo from July 25 was tagging along as well. Here are two views of an adult Henslow's Sparrow during its molt:
The fresh scapulars, coverts, tertials, wing and tail feathers, and the bright eye ring are really evident on this individual.