Managing a Deer Population
In 1994, Dauphin County, Pennsylvania had an estimated deer population of 12,427 animals,
distributed as follows:
Newborn males
Newborn females
One year old males
One year old females
Adult males
Adult females
1379
1286
679
634
1707
3714
Available game commission statistics indicate that:
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About 150 deer are born for every 100 adult females in the herd
About 52% of the newborns are male and 48% are female
55% of all newborns reach one year of age
60% of all one-year-olds reach adult age
90% of all adults live through the year
The deer population can now be modeled using the following formulas:
M0
F0
= .52 x 1.5 x F
= .48 x 1.5 x F
M1
F1
= .55 x M0
= .55 x F0
M
F
= .90 x M + .60 x M1 - .15 x
M1
= .90 x F + .60 x F1 - .15 x
F1
Where M0 is the number of newborn males, F0 is the number of newborn females, M1 is the
number of one-year-old males, F1 is the number of one-year-old females, M is the number of
adult males, and F is the number of adult females.
The total size of the herd is: M + F + M1 + F1 + M0 + F0.
Use this information to create a spreadsheet to model the deer population in Dauphin County for
the next five years. Your spreadsheet should look something like this:
Enter the following formulas into these cells:
B14
C14
D14
E14
=int($D$8*$D$7*G13)
=int((1-$D$8)*$D$7*G13)
=int($D$3*B13)
=int($D$3*C13)
=int($D$4*D13+$D$5*F13F14
$D$1*F13)
=int($D$4*E13+$D$5*G13G14
$D$1*G13)
H14 =sum(B14:G14)
These formulas will compute the current year's deer population based on the previous year's
population. To fill in the rest of the spreadsheet, select the cells from B14 down through H18.
Then use the Fill Down command. Cell references will automatically be adjusted.
Now try different values for the "harvest rate" and note how this affects the size of the herd over
time. Can you find a value that keeps the size of the herd fairly stable? Try different values for
the survival rates. How do these affect the size of the herd? Try different values for the birth rate.
How does this affect the size of the herd?
Print a copy (or copies) of your spreadsheet. Write a one-page report summarizing your results
(i.e. how these factors affect the size of the herd).