Spatial requirements of species have often been related to body size, usually focusing on one area variable and one taxonomic group at a time. Here, we carried out a quantitative meta-analysis and developed a minimal model, covering different types of spatial characteristics and several species groups.
In a global literature review, 46 empirical regressions on home ranges and geographic ranges were collected, covering thousands of species monitored in various countries. In addition, regional data on minimum key population patches of 167 species occurring in the Netherlands were retrieved from reports. To check consistency, a theoretical model was derived from rate and density variables based on energy equivalency. The minimum number of individuals needed to sustain a viable population was considered invariant to size. According to the equations, areas were expected to scale to mass with an exponent of 1 for the individual home range and of about ¾ for the minimum population ranges.
The meta-analysis of the empirical regressions showed that average slopes for individual home ranges were between 0.74 for cold-blooded species and 1.05 for birds and mammals. Minimum and average species geographic range scaled to mass with exponents of 1.16–1.29 and 0.28–0.46 respectively. Allometric correlations for the minimum key patch area were weak. The intercepts indicated that carnivores require more space than equally sized herbivores, while homeotherms occupy larger areas than heterotherms. Observed slopes and intercepts were often near model estimations, but important deviations from the average level were noted as well, especially for birds.
Although variability was substantial in some cases, allometric approaches can contribute considerably to understanding and protecting area requirements of species.