Changes in Population
"The size of any population doesn't stay the same for long"
Births and Deaths
Populations change all the time, This is is due to birth rate. The word birth rate means the number of births in a population in a certain amount of time. Suppose a wolf pack of 50 produces 100 cubs in a year, the birth rate is 100 cubs a year. Eventually the circle of life happens, and the wolves will die, this is death rate. The main way wolves leave a population.
A population statement can be written as a mathematical statement using the less than or greater than sign.
If birth rate > death rate, population size increases
If death rate > birth rate, population size decreases
Immigration and Emigration
Another way populations can change is when individuals move into a population, this is called immigration. Populations decrease in size when individuals leave a population, this is called emigration. Immigration means moving into a population, emigration means moving out a the population