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Capture-recapture problems

Density problems

 

 

1. Suppose that naturalists catch, tags, and release 50 deer in a forest. After allowing time

for the tagged deer to mix with the others, they catch a sample of 100 deer, 10 of which have

tags. What is the estimate for the number of deer in the forest?

 

 

2. Suppose that wildlife workers capture 328 penguins on an island, mark them, and allow them

to mix with the rest of the population. Later, they capture 200 penguins, 64 of which are marked.

What is the estimate for the number of penguins on the island?

 

 

3. Suppose that the high school in a town has 500 students. A random survey of 200 people in

the town finds 40 high school students. What is the estimate for the number of people in the town?

 

 

4. Visitors conducted a capture-recapture experiment to determine the number of taxi cabs in

Edinburgh, Scotland. On the first day, observers saw 48 taxicabs. The next day they observed

52 cabs, 20 of which they had seen the previous day (The Wildlife Society, October 1978).

What is the estimate for the number of taxicabs in Edinburgh?

 

 

5. In a study of raccoons in a certain region of northern Florida, 48 animals were captured using

cages baited with fish heads. The raccoons were marked and released. In the following week 71

raccoons were captured, 31 of which had been marked (Pollock in Brook and Arnold, The Fascination

of Statistics). What is the estimate for the number of raccoons in this region?

 

 

6. Suppose that a naturalist determines that there are 500 deer in a rectangular forest that is

5 miles wide and 10 miles long. What will the density of the deer be per square mile?

 

 

7. Find the density per acre for problem 6. There are 43,560 square feet in an acre.

 

 

8. Suppose that a naturalist estimates that there are 50 raccoons in an area that

measures 5280 feet by 5280 feet. What is the density per square mile?

 

 

9. Find the density per acre for problem 8.

 

 

10. Suppose that wildlife workers capture 20 pheasants in a square mile area. They tag them

and release them to allow them to mix with the rest of the population. Later they capture

30 pheasants, 15 of which are marked. Determine an estimate of the pheasant population for

the square mile and determine the population density per acre.

 

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