Sure, trees produce oxygen that help us breath and animals help with the production of food
Autobiography! This should be it.
When migrating, birds usually migrate when there's not enough food, shorting of daylight, and when it's getting colder in winter. Birds that migrate do so in the late summer through the fall and in the late winter through the spring. Birds and use a radical pair-based compass to "see" the Earth's magnetic field when migrating.
