Figure 11.11 Abundance and range size of birds. Data from 457 species of North American birds show that bird species with higher abundances are generally more widely distributed. However, this relationship contains a great deal of variation around the line of best fit due, in part, to annual variations in abundance and geographic ranges.

Data from B. McGill and C. Collins, A unified theory for macroecology based on spatial patterns of abundance, Evolutionary Ecology Research 5 (2003): 469–492.