Grasshopper Sparrows are fairly secretive, ground-nesting specialists of dry fields, barrens, and open grasslands. Like many sparrow species who nest in similar habitat (e.g., Field, Vesper, and Clay-colored), they're often easiest to observe when singing from an exposed perch. Their buzzy song is insect-like, and is perhaps influenced by their grasshopper-rich diet.
Field marks include a white central crown stripe, white eye-ring, and buffy chest, but these can be difficult to appreciate without a spotting scope. Becoming familiar with their head shape and overall profile (by observing singing birds) is perhaps more useful for those armed only with binoculars.
Though mostly encountered on their breeding grounds in late spring and summer, Grasshopper Sparrows occur as migrants in other habitats, sometimes late in the year. I photographed the following bird at a coastal location in early December. To learn more about Grasshopper Sparrows, visit All About Birds.