Students will determine the population of the Eastern Cottontail for each month, up to 12 months, using the equation G = rN .
The Eastern Cottontail (Sylvilagus flordianus) has a gestation period of 26.5-30 days. Typically 4-7 young are born, usually 3-4 times per year. If the birth rate is exponential, the population of cottontails living in the field after 12 months, could be found using this equation:
G = rN
G = population growth with time
r = net population growth rate per individual per time
N = number of individuals
The initial population size is 35 individuals. As time goes on, reproduction takes place and N, the number of individuals increase. To determine the net monthly increase G, multiply N by r. The new population size for each month then is N + G. The new N for each month is the previous months new population size. Display the graph on your calculator to be sure that you are on the right track. Lastly, students will create a graph to display their results.
This is a great activity to reinforce population studies, population terminology, and graphing skills.