What does manipulated variable mean?

Several bird species feed in a certain species of tree. each bird species feeds in a different part of the tree. which statement is true of these bird species? a. they have adapted to different niches due to competition b. they have a carnivorous relationship with the tree species. c. they have adapted to different niches due to predation d. they have a symbiotic relationship with the tree species.

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?

Adistinctive characteristic of mammals that is not observed in other vertebrates is