MEASURING POPULATIONS pp

birth rate: # of births per given time death rate: # of deaths per given time Growth rate: the amount a population size changes in a given time

GROWTH RATE Net reproduction r = birth rate – death rate Growth rate= r = b – d/ total population If the value is +, the population is growing If the value is -, the population is declining

EXAMPLE of per capita rate In a rat cage containing 400 rats, 100 rats are born and 40 die. Growth rate= r = (b – d) / total population r= #of births - #of deaths total population r= = 60 =

What the per capita means You can estimate the next year’s population size EX. original population + change = new pop = 460 How big would the population be the next generation? 460 x 0.15 = = 529