Answer:
they dont know the exact number of ducks
Explanation:
they dont know the exact number so they use and educated estimate/guess to determine how many ducks are in that area and base it off of the birth and death rates of the ducks
With so many ducks it is impossible to count them all once, they are birds so they move from place to place and because there are so many it makes it impossible. By estimating you get close to the exact number.
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