Answer:
Biotic factors are just everything living (bio-) in an ecosystem. So they're bound to vary in every ecosystem, based on the biome, climate, other food sources available, et cetera.
Do you see flamingoes in the forest? No, you say? Well, they're living; they're biotic factors. They aren't in a forest or a jungle ecosystem because that's not their habitat and they don't thrive there.
