We spotted a bird that looked just like the sign, complete with grass and everything! So we got excited. Unfortunately, we saw a bird take flight from behind the grass and it had the distinctive flashy black and white wing pattern of the willet. We're not sure if it was the same bird or two different birds in the same area.
Catoptrophorus semipalmatus & Charadrius vociferus
On our return trip, we were positive about these IDs.