Exercising is hard enough, but now, people near Denver have to deal with another obstacle: a dive-bombing bird who likes to swoop down and attack joggers, walkers and runners who pass by.

The sky above us is a complex ecosystem, just like the land and sea. A new field of research is bringing a fresh ...

By destroying the environments where birds live, introducing alien predators and damaging the environment in other ways, humans gradually put birds, and of course other species, at risk.