Over time, a river cut through a field where some mice lived and some birds were nesting. Tell over time why the mice developed into 2 different species, but the birds did not

Some of the mice had to adapt to the change in the environment. The birds, since there was no change in the environment for the birds, the birds didn't need to adapt to anything.

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.

c. live where it’s cold and icy