Counting Tiny Crocodiles

Working to preserve a rare American reptile in the Florida Keys

This post was written for Open Spaces, the official blog of the U.S. Fish and Wildlife Service. It’s part of a monthly series featuring SCA interns writing about their experiences working to promote, protect and study wildlife on public lands all over the United States. Today, Caitlin Sebok checks in from Florida Keys National Wildlife Refuge.

It’s a typical Tuesday in Key Largo, Florida, at Crocodile Lake National Wildlife Refuge for Chari Adames-Smith (a refuge volunteer) and me.  We head out into Barnes Sound in our kayaks to check the trail cameras set up at various American crocodile nesting areas.

That’s right, you read correctly, American crocodiles — Crocodylus acutus. Occupying a narrow range of coastal habitat in South, Central and North America, they currently number about 2,000 in the United States. That entire population is concentrated in the mangrove swamps of southern Florida, where they can grow up to 13 feet in length and weigh nearly a ton. Bet you thought you’d have to cross an ocean to see a crocodile in the wild, right? Wrong! You don’t even have to leave the country.

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Crocodile hatchlings hiding in the mangroves.

As we get to our last site, something catches my eye as it hops from the roots of a red mangrove and into the water. Little warning chirps confirm my sighting. I try to whisper, but I’m so excited it comes out a shout: “Chari, we have babies!” 

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A crocodile mother carries an egg down to the water.

As the baby crocs scatter into the mangroves, I jump from my kayak to search for the nest along the bank of this small island. Sure enough there is a shallow hole near our trail camera where the mother crocodile excavated the nest. We were lucky enough to catch 760 photos of the mother carrying the hatchlings and nesting material down to the water!  She worked for more than 20 hours making sure every single baby was out of the nest.  After that impressive feat of endurance, she left them to fend for themselves in the well-protected mangroves.

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Caitlin is ready for some crocodile wrangling.

Fast forward to a week later and it’s time to catch some hatchlings!  We have a busy night ahead of us because by this time, two more nests have hatched with the help of mama crocodiles – as the mother excavates the nest, she likely helps the babies out of the shell. Our crew— me, Chari and several Service employees—are led by University of Florida biologist Caitlin Hackett. We paddle to the first nest Chari and I found, but seeing that the baby crocs have already relocated, we refocus our attention on the other two nests. 

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How you weigh crocodile hatchlings.  

When we spot a pod of baby crocodiles hiding out in the mangroves closest to shore, we paddle up fast, grabbing them left and right with our bare hands and placing them into buckets. Surprisingly, the hatchlings don’t even try to bite you. They chirp warning calls from beneath the mangroves and scatter in all directions, but we try to catch every last one. Chari is shoulder-deep in the water grabbing the sneakiest little guys from within the roots, while Chris and Kate tag-team the largest group and almost tip their canoe. Jacob and Caitlin are paddling the perimeter, catching the stragglers, armed with pilstrom tongs for the ones that are hardest to reach. I manage to catch five without even falling out of my kayak!  We end up with 25 total— pretty good for our first round!—and move on to working them up.

We help Caitlin weigh and measure the hatchlings, then hand them over to her so that she can give each of them an individual identification mark. We do this as part of the mark recapture program for the American crocodile, which allows biologists to monitor the growth, survival and population trends for crocs in South Florida. During our second round of hatchling-wrangling, we catch nine, bringing our total for the night to 34. They weigh between 50 and 62 grams each, and measure between 25.0 and 27.6 centimeters.  Once processed, they are returned to the mangroves and immediately rush back into hiding. After about two weeks, the babies will disperse throughout the refuge.

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Baby American crocodiles have a survival rate of 10 percent.

The life of a baby American crocodile is a tough one –  they make easy prey for herons and large fish such as tarpon. At 10 percent, their survival rate is low, but that’s typical among wild reptiles. Even with those odds, South Florida’s overall crocodile population has increased since monitoring began back in the 1970s, from just a few hundred to the couple of thousand that we count today. That increase has been aided by the protection and restoration of nesting areas that were once slated for development in North Key Largo and other parts of Florida. Because of this success, American crocodiles in Florida were downlisted from federally endangered to threatened in 2007.

Working as an SCA intern at Crocodile Lake National Wildlife Refuge has been a great opportunity. I’ve gained valuable hands-on experience as a field technician, as well as a deeper appreciation for the effort that goes into conserving valuable species, especially those found only in southern Florida. And hey, not everyone gets to say that they’ve wrangled 34 crocodiles in a single night!

 

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