Patuxent Wildlife Research Center (PWRC)    Migratory Bird Research (MBR)    Comments/FAQ(comments)

Trend Map

This map provides our best guess of population change for the species over its range. Areas of increase are blue, and areas of decline are red. Areas where there is no apparent trend, or where we do not have enough information to say that a trend exists, are indicated by white stipples. Occasionally, we were not able to produce a contour map of population change. For these species (including Fulvous Whistling- duck, Cave Swallow, Marsh Wren, American Dipper, and Varied Thrush), we produced a map with point data indicating route trends.