The secret lives of Florida's crocodiles: study reveals long-distance commutes

The Guardian

31-01-2025

New research has revealed surprising details about the secret lives of crocodiles swimming through Florida's waterways, including the long distances some travel in search of food and shelter, and their ability to slither unnoticed through populous neighborhoods.
The preliminary study provides rare insight into the habits and habitat of the species in a state more commonly associated with its estimated 1.5 million alligators. Florida has a non-hatchling population of about only 2,000 American crocodiles, the researchers say, which made it difficult initially to find and tag a sufficient number of the reptiles in urban areas in order to observe them.
What they did find was that each crocodile exhibited more individual behaviors rather than following any systematic routines or actions, although all preferred to stay away from human encounters where possible.
'Crocodiles are a shy species that tend to avoid people. Our tracking shows that they are able to navigate through south Florida's extensive canal system and various waterways usually going unnoticed by residents,' said Vincent Deem, the study's lead author and crocodilian research program leader at the Florida fish and wildlife conservation commission (FWC).
'This is great news for us as it shows that peaceful coexistence between crocodiles and humans is not only possible, but is the norm.'
Deem said one of the surprising findings from the research so far was the distance some of the 15 tagged crocodiles chose to travel.
'Each crocodile we have tracked exhibits somewhat unique movement patterns. Some utilize a very small home range, while others travel far and wide,' he said.
'Several crocodiles we have tagged travel back and forth between both urban and wilderness areas. They are able to swim dozens of miles in only a few days if they want to, so a croc spotted in an urban area today may be out in Everglades national park tomorrow, and vice versa.'
The ongoing study was paid for by FWC's non-profit support organization, the Fish and Wildlife Foundation of Florida (FWFF), in the hope its findings can play a future role in how urban planning and wildlife conservation intersect.
Wildlife officials have recorded only two confirmed bites of humans by crocodiles, but are keen to find ways to keep both safe. Florida is one of the top two fastest-growing states, and crocodile numbers are also increasing despite their threatened status, pointing to potential conflicts ahead.
There have already been an increasing number of sightings of, and human interactions with, crocodiles in recent years, including repeated appearances of one at Melbourne Beach that has been relocated several times but keeps returning to its favored habitat.
Residents of one Miami neighborhood this week launched a petition for FWC to remove 'nuisance' crocodiles they say regularly roam areas close to a park and schools.
As Florida's cities expand, Deem says, crocodiles are learning to live alongside humans in surprising ways. Crocodiles in more densely developed areas had smaller home ranges, while those near larger natural waterways roamed farther.
And with many of the state's inland population centers close to its extensive network of engineered and natural waterways, including canals and rivers, the chances of people living next to resident or transient reptiles without ever knowing they are there are also increasingly high.
Crocodiles used certain areas repeatedly, the report says, and traveled frequently to and fro, indicating they have adapted to their fragmented surroundings: 'This indicates that these crocodiles were selectively using these high-use areas while spending little time in the habitats in between these locations, using them instead as travel corridors.'
The first crocodiles were trapped in the summer of 2022 in Brevard, Palm Beach, Miami-Dade and Monroe counties, some in partnership with theFlorida Power and Light energy company and officials of the naval air station at Key West, who allowed access to their lands.
Laboratory research, including blood sampling, took place with the help of the University of Florida and the animal advocacy group Florida SPCA.
Deem said it was too soon to draw 'strong' conclusions because their work was still at a relatively early stage. A final report and peer-reviewed research studies are not expected to be completed and published until next year.
But he said his team was excited by their progress so far, and had produced a video posted to YouTube about their work and its purpose. The footage shows how the reptiles were trapped and tagged, with examples of the range of some of the crocodiles across Florida's southernmost counties.
'We hope that at the conclusion of this study we will be able to evaluate how human activities affect crocodile movements, factors involved in road crossings and habitats that are utilized by crocodiles in urban surroundings,' he said.
'Information from this study can be used by state, federal and local governments to improve management of crocodiles by incorporating land management designs and practices that would promote the safe and sustainable coexistence of crocodiles and humans in south Florida.'
Andrew Walker, president and chief executive of FWFF, said the group funded the study partly through proceeds from its specialty wildlife license plate.
'Understanding how wildlife adapts to urban environments is critical to protecting both people and animals as Florida continues to grow,' he said.
'This study provides invaluable data to help us better manage human-crocodile interactions and ensure the long-term survival of this incredible species in our state.'