Trends and Characteristics of American Alligator Bites on People in Florida

  • Frequency of unprovoked bites by free-ranging alligators, classified by severity of injury (Major or Minor), in Florida, 1970‒2014.

  • Trend (solid line) and 95% mean confidence interval (dashed lines) in the frequency (A) and rate of bites per 1 million Florida residents (B) of unprovoked alligator bites on people resulting in major injuries during 1971‒2014 in Florida. Dark bars at bottom represent the frequency (A) and rate (B) of confirmed fatal attacks.
  • Locations and frequencies of alligator bites in Florida, by nearest city to incident site, 1948–2014.

Between the years 2000 and 2020, over 6 million people moved to Florida, which is equivalent to the entire population of Missouri. We live in a popular state, both as a home to millions of people and a mecca for worldwide tourism. As the population continues to grow, more and more development will occur near areas that are habitat for many species of flora and fauna, including the American alligator (Alligator mississippiensis). With increased interaction between humans and alligators, alligator bites have become more common. This project was born out of a need to understand the reasons for alligator bites and providing science-based recommendations for preventing bites can make the general public more likely to accept living in close proximity to alligators. This will aid in their long-term conservation in our rapidly developing state.

This project traces back to the 1970s when alligator bites were rapidly increasing in Florida, following state and federal protection. As questions arose from the public and Commission management staff about the causes of bites and safety measures to prevent them, FWC alligator research staff were asked to provide an assessment. Assessments were made periodically until 2007, when the current analysis was initiated to do a complete assessment.

Biologists evaluated alligator bite incident reports conducted by FWC law enforcement staff, reports from other agencies, medical examiner reports and news reports to provide the best available information about incidents. Researchers then combined this with general knowledge about alligator behavior and biology to provide a comprehensive account of each incident and the circumstances surrounding it. Then, biologists categorized incidents for further analysis of bite characteristics and trends over time.

Researchers classified 372 bites as either unprovoked or unintentionally provoked and used these in further analyses. Major injuries to victims occurred in 247 bite incidents. The estimated annual number of bites resulting in major injury to the victim increased from 3.5 to 7.0 during 1971–2014. The number of bites per Florida resident did not show a significant trend during 1971–2014. No significant change occurred in the frequency of fatal attacks during 1971–2014. A high percentage of bites (41.8%) occurred in unnamed water bodies, which were generally small or man-made. Most (93.7%) victims were Florida residents, and 58.7% resided close to the incident site. Victims were predominantly male (81.4%), and adults were more frequently victims than were adolescents or children. Most victims (93.9%) were in the water or near the shore when bitten, and were more likely to sustain major injuries if the bite occurred in deeper water. Male alligators were more frequently (76.9%) responsible for bites. Researchers found only 1 instance in which a bite was associated with defense of eggs or young by an adult female alligator. Evidence of people feeding alligators before the bite was documented in 34.7% of bite incidents. Twenty-two fatalities were attributed to alligator attacks, but biologists could not discern a pattern in the ages of victims. Alligators responsible for severe or fatal bites were predominantly in good condition with few deformities or injuries. Most alligator bites in Florida appeared to be attempts at feeding, although 36.8% of incidents entailed a single bite followed by immediate release, suggesting that alligators were unsure about their prey or were biting in defense. The risk of alligator bites can be reduced by educating people likely to interact with alligators and by selectively removing problem alligators in human residential areas and water bodies used regularly by people for swimming, wading and shoreline activities.

This project was primarily data-based, with most of the time spent in the office, since the researchers were mostly looking at alligator bite incident reports after the fact. FWRI researchers were involved with extensive document research, data management and statistical analysis. Occasionally, alligator research staff investigated bites to gain first-hand knowledge of incidents. Alligator bite incidents occur statewide but the analysis was conducted by staff from the alligator research project and the Center for Biostatistics and Modeling at the FWRI Lovett E. Williams, Jr. Wildlife Research Lab in Gainesville. This project concluded in October 2020, and the final report and a peer-reviewed journal article have been provided to alligator management staff to use when developing alligator management and safety programs.

Outside of Florida and FWC, other states and countries will find this work useful in developing or modifying their alligator/crocodile management programs. This project was funded through the State Game Trust Fund. FWRI’s Wildlife Research group led this study, additional work was provided from FWC Division of Game Management, Alligator Management Program and the FWC Division of Law Enforcement.