Competition among species occurs when different species vie for the same resources, such as food, water, or habitat. This struggle can lead to various outcomes, including the adaptation of species to reduce competition or the decline of one species if it cannot compete effectively. In ecosystems, competition can shape community structure and biodiversity. For example, in a forest, both squirrels and birds may compete for nuts and seeds. This competition can influence their feeding habits and nesting behaviors, ultimately affecting the overall health of the ecosystem.