May 27th, 2009

Panthers and airboats


I’m standing in a marsh surrounded by frost-blasted mangrove shrubs, their foliage dead and chocolate-brown. Layne Hamilton, project leader of the Ten Thousand Islands National Wildlife Refuge, is pleased about this. Since freshwater flow was channeled and diverted by developers (see yesterday’s post), the salinity of the marsh has been increasing, and as a result mangroves have been creeping inland, altering the nature of the place.

Which way now? Joyce, Andy and Layne ponder the best route to the next sampling station.

Which way now? Joyce, Andy and Layne ponder the best route to the next sampling station.

In the 1920s there were about 4000 ha of mangroves in the refuge area; now there are more than 7000 ha. The plan to restore the marsh includes restricting the mangrove invasion and burning off some that have already encroached. Frost is helping keep down the mangroves’ prolific regeneration.

While Andy From and Joyce Mazourek go about their data capture, Layne tells me about the history of the marsh, known as the Picayune Strand. It was developed for real estate in the 1960s as the Southern Golden Gates Estate, but it never took off, and by the 1980s had become a haven for outlaws, poachers and drug runners. The Fish and Wildlife Service bought out the property owners in the 1990s, and the area was turned into a state forest.

Salt crystals on a mangrove leaf attest to the ability of many mangrove species to exude excess salt from their tissues.

Salt crystals on a mangrove leaf attest to the ability of many mangrove species to exude excess salt from their tissues.

“It was seen as a great restoration opportunity for the western Everglades,” says Layne, who has been managing the project for the past seven years. As well as providing an ecological asset, there’s the thought that a restored wetland could help mitigate sea level rise. Mapping the vegetation and researching the hydrology are part of the baseline study being done before freshwater flows are restored.

Thunderheads are moving in our direction, blackening the sky. Andy is ready to pull the plug on the trip if they get any nearer. For someone from a country where electrical storms aren’t a major threat, the prospect of lightning strike is new to me, but it’s a daily reality in Florida as the hurricane season draws close. No one on the boat is taking the billowing clouds lightly. “An airboat on a marsh is a lightning rod,” says Andy.

Skimming across the marsh.

Skimming across the marsh.

But the clouds come no closer, and we continue crisscrossing the marsh, occasionally getting stuck in the mud. When that happens, we all get off the airboat while Andy guns the big prop, waggling the rudders left and right, trying to move the machine into deeper water. In fact, we’re lucky to have been able to use the airboat at all. South-west Florida has had a drought this year, and a week ago the marsh was almost dry.

Late in the day, Layne finds panther footprints in the mud. As it happens, she also leads the Florida panther recovery programme, and tells me about the big cats. There are only about 100 of them left, she says—though that’s three times the number there were in the mid-1990s.

A big problem has been inbreeding. When a species hits a population bottleneck like the panther has, all kinds of debilitating diseases and deformities crop up, jeopardising recovery. “As a subspecies, they were just about to blink out,” says Layne.

The heart of the recovery programme has been to introduce the panther’s close relative, the western cougar, from which it is physically indistinguishable. “We brought in eight females from Texas, and they are helping fill in the holes in the genome of the panther.”

Further obstacles in the way of recovery are a disease called feline leukaemia, which jumps from domestic cats to panthers, and pseudorabies, which panthers pick up by eating feral hogs, and which kills them almost immediately. But Layne says the top cause of mortality is intraspecific aggression. Male panthers need about 200 square miles of range, and if they don’t get it they attack and kill females and kittens.

Andy sees the panther; I see the sign :(

Andy sees the panther; I see the sign 🙁

The public hasn’t exactly embraced panther recovery with open arms. It’s a fearsome predator, and seeing road signs advising motorists to watch out for panthers no doubt causes unease among some Floridians. “It will take a lot of outreach and persuasion to get communities to be comfortable with a larger panther population,” Layne says.

That night, driving back to the house where we’re staying, Andy suddenly shouts, “Look! Panther!” Of course, I am looking in the other direction, and by the time I look where he is pointing the cat has slunk into the shadows. It’s the first time Andy has seen one in all the years he’s been coming here, and I don’t begrudge him the sighting for one minute, but I can’t help thinking that it follows the well-known Law of Journalistic Avoidance that is part of the wildlife creed. I have to make do with photographing the sign.

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4 Responses to “Panthers and airboats”

  1. Cheryl Warne says:

    In your caption of a picture of salt crystals on a mangrove leaf, you mention that “many” mangrove species have this ability. I thought salt management was a characteristic of all mangroves; indeed a necessity.


  2. The general rule of thumb is that some mangroves are excluders and some are exuders, which is to say that some mangroves have the ability to restrict entry of salt into their tissues through osmotic barriers in their roots, while others are good at getting rid of excess salt through their leaves. On the leaf I photographed the sun had dried the exuded salt to form crystals, while leaves of the same tree that were in the shade were quite wet with salt water that had been exuded overnight.

  3. Andy From says:

    I didn’t realize you were taking pictures from the rake of the airboat. Fantastic picture!

  4. Jeremy Warne says:

    Exuders and excluders… classic. 😀