Body Mass in Common Loons ( Gavia immer) Strongly Associated with Migration Distance.

The article discusses the relationship of body mass of common loons with migration distance, based on a study to examine body mass, tarsal width, and bill length of common loons from satellite tracking data in breeding territories in North America. Study results show that body mass is inversely proportional to migration distance, and differences in body mass between male and female loons increase with decreasing migration distance. Males, for example, were larger than females in coastal areas.