Summer range data collected by the United States Geological Service (USGS) as part of the annual Breeding Bird Survey (BBS). Each orange circle represents a BBS sighting between 1999 and 2004.
Winter range data collected by the Audubon Society as part of the annual Christmas Bird Count (CBC). Each blue circle represents a CBC sighting on a route surveyed at least 5 times between 1990 and 1999.
Year-round range is determined by comparing proximity of BBS and CBC sightings. If BBS and CBC sightings of the same species are within 200 kilometers, sightings are colored purple.
In all cases, abundances have been adjusted to reflect yearly averages.