Stomach fullness shapes prey choice decisions in crab plovers (Dromas ardeola)
Fig 4
Energy intake rate (ei/hi) (mg/s) was plotted versus ballast (ash) intake rate (ki/hi) (mg/s) for both crab species. The grey triangle represents Macrophthalmus (n = 28), the light blue square represents small Portunus (n = 23) and the blue dot represents large Portunus (n = 43). Arrows represent the standard error of the mean. The inset gives a more detailed view of the Portunus size classes. The long solid black line represents the slope in terms of energy per ballast (ei/ki) for Macrophthalmus, whereas the short solid black line on the left represents the slope for Portunus. The solid red line represents the digestive constraint (c) (0.16 mg/s ash). For both prey species ki/hi > c, which means that the highest long-term energy gain can be obtained by choosing the prey with the highest slope (in this case Portunus).