The Panther's New Genes

Wildlife Conservation, January 2003

Ten years ago, the Florida panther was in a desperate state. Habitat was shrinking, highway deaths were commonplace, and the population was down to about 30 individuals. Many of the remaining cats were closely related, sporting the kinked tails and cowlicks that are considered signs of inbreeding. More disturbing was the impact on the males, many of which were cryptorchid, with undescended testicles and low sperm counts. This once abundant carnivore seemed poised to go extinct.

For years, biologists claimed that the Florida panther was a unique subspecies and should be preserved in its pure form, kinked tails and all. But in 1995, state and federal managers changed their tactics, emphasizing the historical mixing of genes, or gene flow, rather than genetic purity. Eight female panthers were captured in the Big Bend region of Texas, the nearest healthy population, and driven 2,000 miles to south Florida. Six of the animals were released among the core population just east of Naples, and two were let out in the Everglades.

The decision to introduce new genes to the Florida population sparked controversy.  Some biologists thought that with assertive habitat protection the Florida panther would increase its numbers and expand its range. And many conservationists, myself included, cling to the hope that endangered populations will bounce back if we simply keep them out of harm’s way.  But sometimes that isn't enough.

Steven O’Brien, head of the Laboratory of Genomic Diversity in Washington, D.C., presented the results of the panther genetic restoration project at a symposium at New York City’s American Museum of Natural History last year. In 1990, 88 percent of the Florida population had kinked tails. By 2000, not a single first- or second-generation kitten born to the Texas females had the characteristic 90-degree crook in the last five vertebrae. At the same time, the population expanded from about 30 cats to more than 80, and they had entered habitats once thought unsuitable for panthers. Today, most males have healthy reproductive systems, and the field biologists’ job is getting tougher. According to O’Brien, the physical stamina of the new offspring “is better than that of their Florida panther parents and grandparents.” Most of the other reports given at the conservation genetics symposium were about troubling trends in dwindling populations. The Florida panther, it seemed, was a success story.

In early March 2002, I accompanied Darrell Land, a panther biologist with the Florida Fish and Wildlife Conservation Commission, on a routine telemetry flight over southwest Florida. Land and his colleagues fly three times a week, 52 weeks a year, to pinpoint the locations of about 20 panthers east of Naples. As we waited for a thick fog to lift, I asked Land about the restoration project. “In my mind,” he said, “it’s less about the uniqueness of the subspecies and more about healthy cats.”

Taking off from Naples airport, we left the terracotta roofs behind and entered a gray-green landscape of swamp forest, pinelands, and hardwood hammocks, core habitat of the Florida panther. O’Brien claims that it was this land—with its mosquitoes and poisonous snakes—that saved the swamp cat. “A hundred and fifty years ago, the Florida panther had a range that spanned the American Confederacy. But by the time we got to the ’70s, everybody thought it was extinct. The only reason it wasn’t is that it was hiding in the swamp where nobody went because it was unpleasant.”

From the bumpy skies above public lands such as Fakahatchee Strand and the Florida Panther National Wildlife Refuge (FPNWR), and adjacent private ranches, Land located 22 panthers that morning. With hand signals, he instructed the pilot to circle above the location of each radio signal, marking the spots on well-worn topological maps.

We circled Panther 83 on the edge of the strand, just north of the Tamiami Trail. Panther 59 was resting off the James Scenic Trail, east of Picayune Strand. One cat was in a hardwood hammock not far from Wild Cow Island; another was within earshot of State Road 832 between Collins Slough and Tom Still Hammock. During our tight circles, I could almost make out the individual palmettos and hoped to catch a glimpse of tawny coat among the fronds. But this careful scrutiny got the best of me.  After the eighth or ninth panther, I started to dread the 45-degree tip of Land’s left hand, the abrupt tilt of the horizon, and the stomach-turning spiral above yet another radio pulse. 

And there were still many panthers to go. Farther north, we circled above forested scraps in the midst of a cattle ranch, the cows and calves lazing in the sun just a hundred yards from a sleeping panther. Ranchland, citrus groves, sugar cane, and truck crops—tomatoes, cucumbers, red peppers, and other produce that fill our salad bowls in winter—do not necessarily exclude big cats.

“There’s a magical percentage of native to altered habitat,” Land explained.  “When it gets too low, cats can’t use it, though one female nested in ten acres of cypress, completely surrounded by tomato fields.”

More worrisome are frost and disease. When stressed by natural and manmade disasters, farmers can make huge profits by selling their land for golf courses or condominiums.

Our last cat was Panther 99, a young male in Corkscrew Swamp. Prior to our flight, Land showed me the skull of a young male, with the broad Roman nose characteristic of the Florida panther and a half-inch puncture just above the eye. The cat bite had been fatal. Most young males will travel far to avoid such encounters, and the Corkscrew ecosystem provides a refuge for adolescent cats. There are no breeding females in the area; so dominant males don’t bother patrolling it. Panther 99 can hunt unmolested by other panthers, biding his time until he’s old enough to strike out for the panther equivalent of steak three times a week and a house atop a hill: a territory of about 150,000 acres, with abundant deer and hogs and four or five female cats. There isn't room for many of these territories in south Florida, but even dominant males grow old or die.  Panther 99 will be waiting.

The 20-year database from these flights has directed state acquisition of core areas and the management of public and private lands. Of course, the cats aren't born transmitting high-frequency radio signals. During the cool months, a capture team replaces old collars and puts new panthers on the air. Roy McBride, a tall and amiable Texan, is responsible for most of these collars. If you want to catch a panther or even a jaguar, McBride is your man. When I visited him on the edge of Big Cypress National Preserve, he met me with a firm handshake and a box of records. His six female hounds circled their kennels outside his front door.

When McBride started tracking the Florida panther, in the 1970s, he and his hounds often spent weeks looking for a new cat. “Now,” he says, “I can’t find a place to exercise my dogs without running into one.” Although McBride doesn’t see much behavioral difference in the offspring of the Texas cougars, treed cats are suffering more injuries. Dave Thompson, conservation director of White Oak Plantation in north Florida, believes these injuries stem from the introduction of new genes. But what’s the difference between a Florida panther and a Texas cougar?

As it turns out, not much. Both cats are pumas, Felis concolor, one of the most widespread carnivore species in the world, found from Tierra del Fuego to British Columbia. Mountain lion, catamount, cougar, painter, and panther are just a few of the common names for this species. Although there are a few characteristics that have been used to distinguish Florida panthers from other pumas—the Roman nose, white flecks on the neck and shoulders (which have since been blamed on ticks, not genetics), dorsal cowlick, and crooked tail—before it became isolated in the swamps of south Florida, its range was contiguous with that of the Texas cougar. There was a small but significant mixing of genes.

It was this historical gene flow, and evidence that all North American pumas descend from a common ancestor 10,000 years ago, that prompted biologists to consider genetic restoration of the panther. Before the last Ice Age, the continent held a stunning array of mammals: North American cheetah, saber-toothed tiger, American lion, ground sloth, mastodon, and mammoth, along with the puma.  But a massive extinction, following Pleistocene glaciers that extended as far south as Illinois, wiped out most of them. The puma probably went extinct on the continent as well but returned from South America after most of the large carnivores disappeared up north. It has prowled much of the continent ever since--at least, until colonists arrived with firearms and axes, and then stick shifts and golf clubs.

After the recent expansion of panthers in Big Cypress, federal biologists applied for a permit to collar the cats in this historically unused area. Dave Maehr, a professor at the University of Kentucky who led the Florida Panther Study Project for nine years, is critical: “Somehow, by having their own capture permit, they’ll be able to better monitor the continued swamping of the Florida genome. You know, I want to pull my hair out and say, ‘Well, if it’s a problem, maybe we should be doing something, like taking the culprits out.’”

Even Land is skeptical of the need for more collars. Since 1981, 112 panthers have been captured, many more than once, as collars were lost or batteries wore down. “I’m desperate to get people off this addiction to radiotelemetry,” he told me. Still nauseous from our three-hour flight, I could see why.  But Land had something else in mind: “Let’s let cats do what they want.”

That afternoon, Land gave me directions to Panther 59, one of the first cats located during our flight. On the highway out to Fakahatchee Strand, I counted 14 wildlife underpasses. The culverts were installed, at a million dollars apiece, to decrease roadkill when Alligator Alley, which sliced through the Everglades, was replaced by I-75 in 1968. Though it’s rare to hear a biologist praise an interstate, Land is forthright in his support for the changes it brought.  Before the underpasses went in, the road was lethal to panthers; collisions with cars were fairly common.  (Later, when I explored one of the culverts with refuge biologist Dennis Giardina, we found raccoon, deer, bear, wild turkey, and otter tracks, along with signs of the Florida panther. As we studied this 40-foot thoroughfare, Jaguars, Mercedes, SUVS, pickup trucks, and 18-wheelers hurled overhead at 70 to 80 miles an hour.)

Panther 59’s collar was inactive when we located him from the air, but I knew from the data of hundreds of telemetry flights that a panther’s day typically begins around 5:00 P.M, when they hunt for deer and hogs, ready to leap upon a victim’s neck as the light begins to soften. I arrived at 4:55, breakfast time for Number 59. 

I urged myself onto the old wreck of a road. Park biologist Mike Owen refers to Fakahatchee as “the Grand Canyon of the Everglades” because of the three-foot depression that runs through it, but that evening, with palms and palmettos leaning into the trail, I could only describe it as spooky. O’Brien’s comment on the new vitality of the panther may have pleased me in the comfort of the Museum of Natural History—where the nearest carnivores were stuffed with straw, their snarls behind plate glass—but here it set me on edge. According to Maehr, “The big issue in the West is mountain lions eating people, but that’s never happened in Florida. In fact, the panther has always been viewed as a sort of demure, laid-back kind of mountain lion.”

I found myself longing for that laid-back Southern attitude. A breeze picked up, and palmetto leaves rustled along the trail. The saw-toothed blades can tear skin, but palmettos provide food and cover for white-tailed deer, black vultures, feral hogs, raccoons, turkeys, and panthers, which use them as retreats to raise their kittens. Noticing the royal palms shattering the waning light, I decided to head back to the car. 

After half a mile or so, I came upon a new impression on the trail. A pawprint.  There was a prominent ridge in the moist sand between the pad and the four thumb-size toes. At first I thought it was from a bobcat, but when I reached down to measure the track, I felt a tingle on the back of my neck—my field guide identified the print as that of a panther. It’s possible that I missed the track on the way in, but the thought that a large cat had just crossed my path and was now up ahead on the trail gave me a thrill that I rarely have in my local woods up north. Still, the print seemed surprisingly small; I could cover it with my palm.

Early the next week, I asked Land about Panther 59. “He’s just one of our cross-eyed, one-testicle, low-sperm-count, inbred males,” he told me. Fifty-nine was pure Florida panther; I could have relaxed—a bit—while moving through his territory.

Back in Naples, I went through 59’s dossier at the Florida Fish and Wildlife office. As it turns out, he has two descended testicles and a straight tail. First captured in June 1995 when he was two weeks old, Panther 59 weighed in at a healthy two pounds, five ounces. Two years later, biologist Larry Richardson caught the young male in a camera trap. Fifty-nine trudged in front of a curtain of saw palmetto, his ears flattened in a wimple of despair. He was probably making a wide detour around an opponent, likely an older male in his prime. Claw marks ran from the top of his head down to his eye, and two more scratches circled his ears. Having dropped his game face, he looked like a defeated boxer after the dressing-room door is closed.

Panther 59 did not keep his head low for long. By the time I went looking for him, he was suspected of having sired at least three litters and was located that evening, courting a female. That same week, the pair crossed the canal from Fakahatchee to Picayune Strand. Although it was drained in the 1960s by the Gulf America Corporation, Picayune is still classic Florida swampland, peddled off in parcels as the Golden Gate Estates, but with no infrastructure—no electricity, sewers, schools, or fire department. In recent years, the state has purchased most of the land, with plans to restore historical water flow and tear up dirt roads, but poaching is still a problem, and the area seems eerily devoid of wildlife. Soon after he arrived, Fifty-nine moved on to the more productive panther refuge.

Over the next few days, I waited for a call from the capture crew, hoping to join on the last recollar of the season. Looking east from a borrowed condo in Naples—between the cumulus clouds and the shadows they cast across concrete roofs, tennis courts, sand traps, shopping malls, and swimming pools—I could make out a thin blue lip of wild land. The panther’s presence helped hold that line.

During my flight with Land, we were never more than 50 miles from downtown Naples, yet we circled over 22 panthers. The great risk to the panther is sprawl. Every biologist I spoke to in Florida turned to a map at some point in the conversation, pointing to barriers to the extension of the panther’s range: citrus groves, Big Sugar, the latest development near Fort Myers, Orlando, Tampa, Miami, and hundreds of retirement villages. An increase of 40 cats in the past decade is important for this endangered species, but Florida attracts 900 new residents a day, almost 40 people per hour. The state is expected to grow by seven million in the next 30 years. That’s seven million more people with basic needs for shelter and showers, fresh produce and frozen meat, air-conditioned bedrooms and cars, and seven million more desires for McDonald’s, Starbucks, Wal-Mart, day golf, night golf, even nature trails—and all that asphalt to take them to their dreams.

The call never came. Though I had spent eight months negotiating permission to join the state capture team, in the end, a refuge administrator insisted on a federal permit to enter Big Cypress for the last capture of the season. There just wasn’t time to negotiate the Byzantine workings of state and federal agencies, with their focus on collaring new cats.

Maehr, one of the leading contrarians to the government’s handling of panthers, wonders if there isn’t a better use for the recent surplus. “It’s a fairly clear prediction that the deer herd should decline dramatically in response to predation, and it should probably drop by an order of magnitude when the next big tropical storm hits and the area floods. It’s not a matter of if, it’s a matter of when. . . . We should try to take advantage of this high density now.” If panthers can be transported from Big Cypress to the Everglades, or from Texas to Florida, why can’t a female or two be moved across the Caloosahatchee north to Highlands County?

The reluctance on the part of the administrators may be their desire to let the panthers cross the river and expand their range unaided. But it also descends from a stinging experience in the 1990s. A few Texas cougars were released in northern Florida to see how big cats would fare, but they were more habituated to humans than the managers realized. When they started showing up in backyards, the cats were removed. One cougar ended up in a hunting pen, where animals are fenced in for lazy hunters—a public-relations nightmare for the state wildlife agency, and one from which it still hasn’t fully recovered. Maehr thinks the managers had better get over it soon: “If the agencies are too spineless to actually move a female or two across the river, then there is some hope that one might do it on its own.”  But the panther may not be able to wait that long.  “A more proactive approach is needed,” Maehr warned, “if for no other reason than the landscape is still changing.”

At the very heart of conservation biology, a paradox has taken root: In order to protect our notion of wilderness, we must meddle in it more and more. Endangered species, especially large carnivores, increasingly need our help—either to add a few alleles to the genetic monotony of isolated populations or to reestablish animals lost to hunting and persecution. But what are we conserving when we add new genes? The Florida cats are now part panther and part in situ genetics experiment. (When biologists noted that Texas cougar 101 was more fertile than expected, having raised eight kittens that survived to maturity, they administered a long-term contraceptive to prevent the female from becoming “genetically over represented.”) If the numbers don’t increase soon, it’s probable that inbreeding will once again take its toll on the panther and more cougars will be needed to restore the genetic health of the population, further eroding its uniqueness.

If a panther is a puma is a cougar, then perhaps it doesn’t matter very much. Perhaps we should be glad that even a fragment of the genes from individuals such as Panther 59—battered in youth but victorious in maturity—have persisted. The eastern cougar disappeared from Appalachia and New England more than a century ago. Whatever unique genetic traits it had are gone forever.