Fig. 4. Foraging time relative to dive depth. Open circles indicate observed foraging times for dives with two or more lunges. The solid lines indicate the predicted foraging time ±95 % CI according to the lunging-costly model. The broken line indicates the predicted foraging time according to the no-cost model. Values of r² are for the lunging-costly models. (A) Blue whales. On the basis of the lunging-costly model, the cost of foraging relative to the cost of travel to and from the prey patch was 3.15 (95 % CI 2.58-3.72). (B) Fin whales. On the basis of the lunging-costly model, the cost of foraging relative to the cost of travel to and from the prey patch was 3.60 (95 % CI 2.35-4.85).