Testing Relationships between Energy and Vertebrate Abundance
Figure 1
Relationship between the log10 of body mass and log10 of density for (a) all mammals (figure based on the original data from Damuth [25]) and (b) birds in North America (figure extracted from Gaston and Blackburn [2]). For mammals, body mass is expressed in kg while density is measured as the number of individuals per km2. For birds, body mass is expressed in g while density is measured as the number of individuals per Breeding Bird Survey (BBS) route (see Brown and Maurer [36] for the original dataset description). As it can be seen, body mass is tightly linked to density for mammals (slope , , ; from Damuth [25]), while the linear relationship between body mass and density is far less tight for birds (slope , , ; these estimates are based on data reconstruction and subsequent analysis from the original data presented in Brown and Maurer [36, Figure 2]).
