None of the items ranked lower in profitability should be pursued on encounter they are out of the diet. Whether a forager takes a lower ranked prey depends on the abundance of all higher ranked prey Foragers should add or drop particular resources from the optimal diet in response to fluctuations in the abundance of higher ranked resources Another Example of Diet and Gender The Ache are tropical foragers of Paraguay studied by Kristen Hawkes, Kim Hill and Hillard Kaplan. Ache hunt with both bows and arrows and shotguns. The results of the study generally support the prey choice model, but with some interesting exceptions. Choices of Ache men, ranked by return rate expected on encounter.
Honey has the highest return rate, and bamboo larve the lowest.
However, return rates for shotgun hunters were greater than for bow hunters. Consequently, the mean foraging return rate for shotgun hunters was higher and they ignored most monkeys and small birds, while the bow hunters took these species. Based on estimated return rates, the model predicted that shotgun hunters would take all birds weighing more than 1kg, and bow hunters all birds more than 0.4 kg. The actual figures were 1.4 kg and 0.4 kg respectively. Although men maximized meat calories, they frequently ignored plant resources predicted to be in the optimal diet and always taken on encounter.