Question 1: A wildlife researcher captures 150 animals, tags them, and releases them back into the population. Later, they catch a second sample of 200 animals, of which 30 are found to be tagged. Estimate the total population using the Capture-Recapture method.

Answer: 1000

Question 2: In a bird survey, 120 birds are captured and tagged. A week later, 180 birds are caught, with 36 tagged. Calculate the estimated bird population.

Answer: 600

Question 3: Explain the assumptions behind the Capture-Recapture method and discuss how violations of these assumptions might affect the estimate.

Answer: Assumptions include closed population, equal catchability, and no tags lost. Violations can lead to inaccurate estimates—e.g., if tags are lost, the population may be underestimated.

Question 4: A researcher captures 80 fish, tags them, and releases them. Later, 150 fish are caught, with 45 tagged. What is the estimated total fish population?

Answer: 267

Question 5: A student makes a mistake in applying the Capture-Recapture formula by using 2 instead of 3 as the denominator in the calculation. Identify and correct the mistake.

Answer: The correct formula is N = (M × C) / R, so the denominator should be the number of recaptured tagged animals, not 2; using 3 would be correct if that is the number of tagged recaptures.

Question 6: Construct a diagram (on the grid) that illustrates a capture-recapture scenario with a total population estimate of 500, where 100 are initially tagged and 120 are recaptured with 30 tagged.

Answer:

Question 7: A population of insects is estimated to be 800 using capture-recapture. If a second sample recaptures 50 tagged insects out of 200 caught, how many insects were originally tagged? Show your working.

Answer: M = (N × R) / C = (800 × 50) / 200 = 200

Question 8: The estimate for a population is 400. After a second capture, 60 tagged animals are found in a sample of 150. How many animals were tagged in the first capture?

Answer: 90

Question 9: Identify and explain two limitations of the Capture-Recapture method when used in real-world ecological studies.

Answer: Limitations include assuming a closed population and equal catchability. Changes in population size or behavior can bias estimates.

Question 10: A researcher mistakenly records the number of tagged animals in the second sample as 60 instead of 70. How does this mistake affect the population estimate? Explain briefly.

Answer: Underestimates the population because the calculation uses a smaller number of recaptures, leading to a lower estimate.

Question 11: Plot the graph of y = 2x for x values from 0 to 10 on the grid provided.

Answer: