Biology / Unit 14 Bio 3545 short lesson, about 20 seconds
Quadrat and Mark-Recapture Sampling Methods
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The idea
Ecologists estimate population size by sampling: a quadrat counts individuals in marked-off areas for immobile organisms; mark-recapture estimates size from the ratio of marked to unmarked in a second sample.
In practice
Tagging 80 deer, then finding 20 tagged among 100 recaptured, estimates roughly 400 deer total.
Where people slip
Mark-recapture assumes marked individuals mix randomly back in — trap-avoidance after marking biases the estimate.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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