Fang Ye said, "Under normal circumstances, a healthy ecosystem forms a web-like relationship in which the numbers of each species fluctuate but remain within a certain range, maintaining a dynamic balance in the ecosystem.
However, when cats that don't belong in the ecosystem are introduced, they prey on birds, weakening the ecosystem's capacity to control insect populations, causing a lack of food for raptors and medium-sized mammals that also feed on small animals."
Ecosystems have been formed through long periods of evolution, where species have competed, excluded, adapted, and cooperated for hundreds to thousands of years, establishing relationships that are interdependent and mutually constraining.