Eagles are considered indicators of environmental quality and ecosystem health because they are at the top of the food chain and are sensitive to changes in their environment. By studying the population size, behavior, and reproductive success of eagles, researchers can assess the overall health of the ecosystem. A decrease in eagle populations or reproductive success can indicate issues such as habitat degradation, pollution, or declining prey species, which can have cascading effects on the entire ecosystem. Therefore, monitoring eagle populations can provide valuable insights into the overall health of the environment they inhabit.