Monitoring Florida's Alligator Population
May/June 2008
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A mini-computer is used
to record alligator sightings and sizes into a database. The computer provides a faster method for logging data than traditional data sheets.
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For thousands of years, the American alligator (
Alligator mississippiensis) has roamed Florida's marshes, swamps, rivers and lakes. This top-level predator plays an important role in the ecology of Florida wetlands. The Florida alligator population has fully recovered from severely depressed levels in the 1960s and, as Florida's human population grows, it has become more important to manage the state's alligator population.
One way the Florida Fish and Wildlife Conservation Commission (FWC) manages Florida's alligator population is through a public statewide harvest program. This recreational harvest program allows for the harvest of more than 9,000 alligators annually. To ensure sustainable harvests, researchers from the FWC Fish and Wildlife Research Institute (FWRI) and biologists with the Alligator Management Program conduct alligator nightlight surveys on selected freshwater lakes and rivers throughout the state. These surveys serve as an important tool to monitor population trends and establish harvest quotas for the statewide harvest.
Alligator biologists typically conduct nightlight surveys using airboats in order to navigate through alligator habitat. Occasionally survey crews use outboard boats in areas where the noise of airboats can create problems with local residents, or otherwise is the best vessel for the survey. Most surveys require just two people, the surveyor and a data recorder. The surveyor also serves as the boat driver. Surveys begin at dusk and may continue into the early morning hours. Using a 200,000 candlepower spotlight, the surveyor navigates and scans the lake in search of alligator “eyeshines.” An eyeshine is a bright amber or red reflection from the eyes of alligators. Once spotted, the surveyor attempts to estimate the size of the alligator. The surveyor relays this information to the data recorder through an intercom system. Surveyors estimate the size of the alligator to the nearest foot when possible. However, an alligator sometimes disappears beneath the water or into the marsh before an accurate size estimate can be obtained. When this happens, surveyors record the alligators in “unknown” size groups. Alligator nightlight surveys result not only in estimated total numbers of alligators within a population, but the estimated numbers of different-sized alligators within that population.
Based on these surveys, researchers believe Florida's alligator population is stable with an estimated 1.25 million animals ranging from yearlings to adults over 13 feet in length. This is evidence that proper management that includes an effective monitoring program, can result in healthy alligator populations that provide important ecological, aesthetic, recreational, and economic values for people in Florida to enjoy.
