White-throated Sparrows can be found in New England year-round but are most numerous in fall, when adults and their immature offspring retreat from their more northerly breeding grounds. They're fond of thickets and forest edges, where they find ample food (primarily seeds and fruits in fall and winter) and plenty of places to hide from predators.
Adult white-throats, as I often call them, come in two flavors, or morphs: those with tan-and-brown head-stripes and those with white-and-black head-stripes (often called tan-striped and white-striped, for short).
Apparently, breeding pairs nearly always consist of one of each morph. You might guess the break-down is along gender lines; however, both morphs may be male or female.
White-throats utter mainly call notes this time of year, but in spring and summer listen for their distinctive whistled songs. Here's a clear example of a northern Maine singer recorded by Tayler Brooks.
For more info on White-throated Sparrows, visit All About Birds.