What are Giving up densities?

The benefit of a food patch is primarily determined by the nutrition value and density of food in an area. A high density of food may encourage an animal to take greater risks whilst feeding. However, as an animal feeds, there is a critical point at which the density of food available no longer out ways the cost of feeding at that site. This is called the giving up density. When the giving up density of a food patch is reached, the animal will leave the site and forage somewhere else.