In a rainforest ecosystem, both chamelons and toucans eat insects. what type of example is this?

This would be called infraspecific competition, or a food web.

This phenomenon is also called Rainforest competition, and it exists on every level, from the big cats (tigers, jaguars and leopards) and anacondas that usually hunt small mammals to the birds and amphibians that go after the same fruit, nuts and insects.