The type of symbiosis hummingbirds feed on nectar is called mutualism. Mutualism is a type of ecological interaction in which both organisms benefit from the relationship. In the case of hummingbirds and flowers, the hummingbirds get nectar from the flowers, which is a source of energy for them. The flowers, in turn, benefit from the hummingbirds because they help to pollinate the flowers, which allows the flowers to reproduce.
Mutualism is an important type of symbiosis because it allows both organisms to survive and thrive. In the case of hummingbirds and flowers, the mutualistic relationship has allowed both species to evolve and adapt to their environment.