ou observe flocks of house sparrows (passer domesticus) and document two foraging strategies: 1) individuals (producers) search for food patches and 2) individuals (scroungers) wait for producers to find food and then feed in the patches found by the producers. the relative frequency of these strategies differs in flocks, and you observe that the scroungers have a high feeding rate (higher fitness) when they are rare in a flock and low feeding rates when they are common in a flock. this is an example of