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1.
10%
2.
The small birds
3.
The medium birds
4.
The large birds
5.
100, 15, 5, 9
6.
see excel spreadsheet below
7.
Approximately 1.37
8.
Growing
9.
The growth rate varies during the first few years as the population structure “works out
the kinks”.
Eventually, the population structure stabilizes and the population growth
converges on a value of ~1.37.
After this, the population growth exponentially (as do the
numbers of each class of birds).
The following projection was made in excel (as were the following figures).
The first row of
numbers in the table below just gives the starting conditions (i.e., 20, 10, 10, 10 birds in the four
classes).
The next row is derived by applying each of the “transitions” to the numbers in each
class from which an arrow arises:
E.g., The number of Large birds at Time 1 = Large(t=0)*0.5 +
Med(t=0)*0.3 + Small(t=0)*0.1 = 10*.5 + 10*.3 + 10*.1 = 9.
You can write this out in Excel by
referring to the cells in the previous row. Once you’ve written down these formulae for t=1, you
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 Spring '11
 Osenberg

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