Graph of the Day: Change in Latitude of Bird Center of Abundance, 1966–2005
This figure shows annual change in latitude of bird center of abundance for 305 widespread bird species in North America from 1966 to 2005. Each winter is represented by the year in which it began (for example, winter 2005–2006 is shown as 2005). The shaded band shows the likely range of values, based on the number of measurements collected and the precision of the methods used. • Among 305 widespread North American bird species, the average mid-December to early January center of abundance moved northward between 1966 and 2005. The average species shifted northward by 35 miles during this period. Trends in center of abundance are closely related to winter temperatures. • On average, bird species have also moved their wintering grounds farther from the coast since the 1960s. • Some species have moved farther than others. Of the 305 species studied, 177 (58 percent) have shifted their wintering grounds significantly to the north since the 1960s, but some others have not moved at all. A few species have moved northward by as much as 200 to 400 miles.
