Why is it difficult for urban cities to get rid of rats?

Because their rate of reproduction is quite fast and because most cities haven't done anything about their Population for a long time meaning they have had a long time to expand their 'territory'

But what do I know, I live in a village

name two ways organisms join a population and two ways organisms leave a population. two ways organisms join a population are birth rate and immigration. two ways they leave are death rate and emigration.

explanation:

i will get back to you let me look in my notes and i will tell you shortly