Figure 2

Examples of the effect of consumer and resource density on resource uptake rate. A. In some studies, a range of consumer and resource densities was available, allowing the use of Method 3 to fit all data to a functional response. In this case, the parasitoid Brachymeria regina parasitized the butterfly Pieris rapae. Data from [18]. B. In other studies, a broader range of resource densities than consumer densities were available. This study shows the success of knots (Calidris canutus) foraging on mussels (Mytilus edulis). Data from [20]. C. In several studies, only variation in consumer density could be related to resource uptake rates, in which case Method 4 was used. These data show the kill rate for wolves (Canis lupus) foraging on moose (Alces alces). Data from [16]. D. In an extension of Method 4, some studies reported variation in metabolic rates associated with population density. In this case, the protist Tetrahymena pyriformis growing in axenic culture. Data from [29].