The Huayruro seed is extremely hard and needs to be scraped or worn down so that it can germinate. One way is to be passed through the acids in the digestive tract of an animal. In the jungle, who would accept to do this service?

The Trompetero, a granivore such as hens are, needs gravel to help grind up grains in its gizzard. Where can it find gravel in the forests of stoneless sediment soils?

Together they have found a solution, through a commitment that in biology is called mutualism: the extremely hard, small and stiff Huayruro can fulfill the task of gravel and the Trompetero, after using it in its gizzard to crush the grains, passes the seed through the digestive tract and expels it, now with its outer shell scraped and worn down, significantly increasing its chances of germination. As an additional service, the Huayruro paints its seeds in bright colors, making them easy to find, and the Trompetero carries the seeds far from the mother tree while it uses them, which means that the seeds are well dispersed.

This is, logically, a humanized description of the process called mutualism and briefly describes what took long years of research to discover, an explanation to the following questions: Why were Huayruro seeds found in the stomachs of these birds if they did not contribute to their nutrition? Why is there greater natural regeneration of the Huayruro where these birds have not been killed off by hunting?

The main source, although they are not the only ones who worked on this, comes from: Peres, C.A. & MG van Roosnalen. 1996. Avian dispersal of mimetic sedes of Ormosia lignivalvis by terrestrial granivores: deception or mutualism??

SOURCE:
Oikos 75, pages 249-258