Why do some hummingbirds defend feeding territories?

Hummingbirds defend feeding territories primarily to secure exclusive access to essential resources, such as nectar, which is a critical food source for these high-energy birds.123

The decision to maintain a territory is based on a balance of costs and benefits. Territoriality is favored when resources are economically defendable—meaning the benefits of restricting access to a food source outweigh the energy costs required to defend it against intruders. Because hummingbirds have high metabolic demands, they may aggressively chase away other hummingbirds or even dive at larger animals to protect their foraging space.213

However, this behavior is fluid. If resources are too widely dispersed or if the quality of the food source declines, the effort required to defend the area may become too costly, leading the bird to abandon its territory. Conversely, if a resource is of extremely high quality, competition may become so intense that maintaining exclusive access is impossible. Consequently, territoriality is most common when resources are of intermediate quality and clumped in a way that makes them manageable to protect.2