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Figure This!

The foundations for the capture-recapture method were established in 1812 by French mathematician Pierre Laplace, considered by some to be the father of probability.

In 1896, Carl George Johannes Petersen, a Danish fisheries scientist, published the results of a study in which he estimated the size of a fish population using the capture-recapture method and brass tags he invented.

The US Census Bureau has considered using the principles of the
capture-recapture method to help count the homeless population in
large urban areas.

Biologists use a number of different ways to mark individuals in a capture-recapture study. Birds are typically fitted with leg bands. Turtles receive non-corroding metal or plastic tags. Large mammals, such as elk or bear, often are fitted with ear tags or radio collars. Migrating salmon are sometimes equipped with tiny microchips inserted under the skin.

To estimate deer populations, wildlife biologists take a picture from an airplane and then count the number of deer in the photograph.

In Iowa, the rooster pheasant population is estimated by rural mail carriers, who count the cackles that roosters make early in the day.

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