Flashcards on Methods for Population Size Estimation
Methods for Population Size Estimation: Direct & Indirect Techniques
Tap to flip · Swipe to navigate
Population size estimation methods
13 cards
Card 1
Question: What are the two main categories of methods used to estimate population size?
Answer: Direct methods (census) and indirect methods (sampling such as quadrat and mark-recapture).
Card 2
Question: What does the direct method (census) involve when estimating population size?
Answer: Counting every single organism in the population.
Card 3
Question: When is the direct census method appropriate to use?
Answer: When organisms are large enough to see, the area is not too large (or can be surveyed from air), organisms are slow-moving, or are stationary (e.g., p
Card 4
Question: Why might aerial photographs or helicopters be used in a census?
Answer: To count large animals or when the area is too large to count every organism from the ground.
Card 5
Question: What is the key difference between direct and indirect methods of estimating population size?
Answer: Direct methods count every individual; indirect methods count a sample and use calculations to estimate the total population.
Card 6
Question: Name two indirect (sampling) methods for estimating population size.
Answer: Quadrat method and mark–recapture method.
Card 7
Question: Write the formula used in the quadrat method to estimate total population size (N).
Answer: N = (number in sample × size of whole habitat) / size of quadrat.
Card 8
Question: List the main steps for using the quadrat method.
Answer: 1) Measure total area; 2) Choose an appropriate quadrat size (same for all samples); 3) Place several quadrats randomly across the area; 4) Count ever
Card 9
Question: Why is random sampling important when using quadrats?
Answer: Because organism distribution may not be uniform; random placement across the whole area gives a truer reflection of distribution.
Card 10
Question: Write the mark–recapture formula for estimating population size (P).
Answer: P = (M × C) / R , where M = number marked initially, C = total caught in second sample, R = marked recaptured in second sample.