In general the main role of birds in the ecosystems is being agents of dispersion. Their ubiquoty make them useful as bioindicators, which is not a ecological role per se, but has been very useful to spread awareness about the importance of preserving our enviroment and the disastrous consequences of the overuse of some pesticides.
- Agents of dispersal of plants, but also of other animals: thorugh their activities birds spread pollen and pollinate different species, seeds, and even animals (Even animals can be spread. Some wading birds relocate fish eggs that get stuck to their legs, thereby aiding in fish dispersal to other parts of a river or marsh).
Songbirds spreading cereal seeds.
Hummingbirds pollinating flowers.