Figure 4.19 Central place foraging. The optimal rate of foraging for an animal that leaves its nest to find food depends on the time needed to travel to a location that contains food and the time spent feeding once it has arrived. For a given benefits curve (the orange line), the optimal rate of prey capture is found by drawing a straight line from the origin of the trip tangent to the benefits curve. The point of tangency indicates the optimal time that the animal should spend searching and the optimal amount of food it should bring back. Spending more or less time feeding in the location, as indicated by black dots, results in suboptimal amounts of food obtained per unit of time.