One reason is for safety! in case you get stranded in a body of water you can keep yourself afloat
Answer:
Cold
Explanation:
They can not survive in cold conditions
Wouldn't the population then become a mix of both turning into purple.
I'm not saying this is for sure but this is what I'm answering for mine thanks to a yahoo answers. d) Migrating bird populations and the carry capacities of local animal species. You don't have to award points or anything I just wanted to try and help. This is what I put on another persons questions as well. I hope this is helpful and accurate. I'm sorry if it is not.