This pair of Florida Scrub-Jays could help boost the genetic diversity of a struggling population in the Sunshine State. Carlton Ward Jr.

Conservation

How Researchers Hope to Save the Florida Scrub-Jay From an Inbreeding Crisis

Human development has caused the bird's gene pool to shrink. An ambitious experiment to relocate scrub-jay families could bring reprieve, while also pointing the way to preserving other threatened species.

A geyser of dust engulfs the tires of Karl Miller’s silver pickup as the truck comes to an abrupt stop on a narrow dirt trail. Dodging the outstretched jazz hands of palmettos and the tangle of scrub on both sides, he slowly opens the back door to unload two soft, mailbox-size carriers covered with a bedsheet. Each contains precious cargo: a single Florida Scrub-Jay that Miller collected in the predawn gray from Ocala National Forest, just north of Orlando, and drove four hours south to Jonathan Dickinson State Park, an 18-square-mile coastal preserve near Palm Beach. The bonded pair in his truck are valuable not only because they’re among a shrinking number of Florida’s lone endemic bird species, but also because Miller has hand-selected them, along with a few other families, to be a part of an ambitious experiment.

Over the past century, human development in Florida has split the jay’s scrub habitat into ever smaller pieces. Because the blue-and-gray, robin-size bird typically travels no more than five miles from home, this subdivision has shrunk the species’ deep gene pool to a series of tiny puddles. Now Sarah Fitzpatrick, a conservation geneticist at Michigan State University, is collaborating with Miller at the Florida Fish and Wildlife Conservation Commission to translocate 5 to 10 scrub-jays from Ocala to Jonathan Dickinson (or JD, as the locals call it). The pair’s hope is that the offspring of the Ocala birds will mate with those at JD, giving subsequent generations a much-needed boost of fresh DNA.

This strategy, called genetic rescue, is neither high-tech nor new, but it is still relatively untested. Scientists have long hesitated to play God with the genes of wild animals, preferring to let evolution manage itself. But several small-scale successes using the tactic in the 1990s, including with the Florida panther and Greater Prairie-Chicken, have made the strategy a more palatable option for species that may be circling the drain. “We’re in such early stages of using this as a tool for conservation in general. I mean, there’s only just a handful of kind of iconic studies that have done this so far,” Fitzpatrick says.

John Fitzpatrick, left, and Reed Bowman pore over maps at Archbold Biological Station, top. Index cards, bottom, are used to track the scrub-jay population over the decades. Photos: J. Adam Fenster/University of Rochester

At JD, Fitzpatrick, Miller, and research assistant Natasha Lehr carefully walk the carriers to a small half-circle clearing next to a stand of scrub oaks, whose arthritic limbs have braided together over time. Miller unzips one carrier, Lehr the other. Fitzpatrick’s job is to track where the birds go when they fly off. Miller’s bird, a male, makes it out first and perches on a nearby snag before dropping out of view into the dense brush. Seconds drag by. The male calls to the female, a strident pshpshpsh. Finally she shoots out in a streak of dull blue and gray and then she, too, disappears.

One factor that makes this prized species an ideal candidate for genetic rescue is the several decades of close study leading up to this moment. This work has demonstrated that the jays’ genetic health is a problem that conservationists need to be worried about—and also has positioned Fitzpatrick to test a solution. It’s a role that she was truly born into.

 

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ohn Fitzpatrick’s love affair with the Florida Scrub-Jay began in 1972 as a summer intern at the Archbold Biological Station. The Harvard undergraduate made the long drive to the dusty town of Venus, then, as now, surrounded by cattle ranches and citrus groves. In the oppressive heat, he helped ornithologist Glen Woolfenden observe scrub-jays tending their offspring. Three years before, Woolfenden had noticed the fledglings at Archbold rarely left their nests. Instead, the youngsters stuck around for at least a year to help their parents raise the next few clutches before striking out. Even then these ultimate homebodies rarely went far. They wouldn’t readily traverse any land that didn’t look like home. Without contiguous scrub, the scientists realized, the jays would rapidly become isolated.

The work stretched into a 50-year study that provided insights on everything from the effect of food on jay reproduction to the bird’s dependence on landscapes burned by fire. Today decades’ worth of yellow Rite in the Rain notebooks fill waist-high bookshelves at Archbold, while index cards with old notes on nest activity occupy a metal filing cabinet. “People ask, ‘After 50 years haven’t you learned everything?’ But these 50 years give us a chance to ask questions that are brand new,” says John, who is now director of the Cornell Laboratory of Ornithology in New York.

In 1988, when John moved his young family to Archbold to take over as the station’s director, he had his two-year-old daughter Sarah in tow. Archbold’s scrub-jays were a part of Sarah’s life growing up, but she preferred to keep company with insects, reptiles, and amphibians. When a gopher tortoise she named Sammy lumbered into their backyard, Sarah raced to her bedroom, grabbed one of her father’s cast-off notebooks, and spent the next few hours sitting on the back porch of the family’s white clapboard cottage noting every detail of what Sammy did. It was, John said, the first of many signs that Sarah loved the natural world as much as he did. 

Meanwhile, John was watching the region’s scrub-jay population in free fall, as predicted by those early observations. The dry, sandy scrub landscape the birds needed also attracted citrus growers and the developers of shopping malls, mobile home parks, and golf courses. The mid-century boom in air conditioning made Florida habitable for the masses, creating a Southern influx that fractured the wilderness needed by Florida panthers, which were among the first animals on the federal endangered species list in the late 1960s.

The scrub-jay, too, was declared federally threatened in 1987. By 1993 only 4,000 breeding pairs remained, a loss of more than 90 percent in a century. Since then, Miller says, their overall decline has continued. The jays are scattered over several hundred small patches of scrub that survive with the help of land managers (see “Each Jay Counts”). Every 3 to 12 years they light controlled fires, which maintain foraging habitat for the birds and clear the dense tangles of brambles where predators like the eastern coachwhip snake can hide. The Archbold study area, home to 80 families of scrub-jays across just about 2,500 acres, is one of the species’ remaining strongholds, along with Ocala National Forest.

Every month, a team led by Reed Bowman, who now directs the avian ecology program at Archbold, still bounces around the area’s rutted dirt trails to keep up the long-running counts. Once the birds hatch between late March and the end of June, scientists begin the banding process and, since 1995, also take a drop of blood for genetic analysis. Even at Archbold, despite adequate habitat maintenance, they saw few scrub-jays coming to the reserve, likely because of the degradation of habitat around the station. The effect on Archbold’s families was dramatic. 

In 2013 population geneticist Nancy Chen, then working with John at Cornell, began analyzing some of the genetic data and mapping family trees. The birds, she reported in 2016, were becoming increasingly and surprisingly inbred. A healthy population with lots of genetic diversity plays with a full deck of 52 cards. Smaller populations have fewer cards, such that no matter how well the deck is shuffled between generations, chicks are still more likely to draw a pair that’s harmful, which can lead to disease and death. The more closely related two parents, the lower their offspring’s chances of reaching adulthood.

One sign of an inbred population is eggs that fail to hatch, which is occurring at Archbold with increasing frequency. If this was true at Archbold, it was likely the case elsewhere. “It kind of freaked out the scrub-jay community,” says Chen, now a researcher at the University of Rochester.

Chen’s scrub-jay work was groundbreaking for conservation biologists not only because it quantified the effect of inbreeding, Bowman says, but also because she showed that the influx of even a handful of outsiders could be crucial to the health of larger populations. These results also told Chen and her colleagues that simply protecting and expanding habitat wouldn’t be enough to save genetically isolated populations of scrub-jays throughout Florida. The birds needed an infusion of fresh genes, and for that, they needed help.

 

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lthough Darwin himself outlined the principle of genetic rescue, the actual practice remained hugely controversial for more than a century. Not only did many hold philosophical objections to the idea, they could also point to several natural and laboratory experiments in which translocating individuals failed in ways hard to predict in advance—a high-stakes risk when dealing with small populations. One of the most famous was a 1950s field study in which ibex from Turkey and Sinai were brought to what was then Czechoslovakia. When the hybrid ibex gave birth at the coldest time of year, and the population died out, the move was deemed to be a bust. Likewise, in a lab experiment in the late 1980s, Scripps Institution of Oceanography researchers tried to see if tiny crustaceans from Baja California could mate with their counterparts off the coast of Vancouver. Although the first generation appeared fine, the second was not.

A chill settled over the field, but in the 1990s biologists in Florida couldn’t sit back and watch as their native panthers were winking out. Only 22 remained in the state—and few were healthy. Texas pumas, scientists discovered, had the right balance of attributes to help: They were genetically different enough to bring in new variety while similar enough to allow crossbreeding. Florida panther numbers immediately rebounded, and the genetics of the population, now 120 to 230 animals strong, remains healthy today. At around the same time, scientists tried something similar with the Greater Prairie-Chicken, importing birds from Minnesota, Kansas, and Nebraska to bolster flagging numbers in Illinois. It, too, seemed to be a success.

In these cases, conservationists had turned to genetic rescue in a last-ditch attempt to save extremely imperiled species or populations. There was little choice. But to further refine and perhaps expand the use of genetic rescue, evolutionary biologist Chris Funk wanted to know how such a strategy actually affected the genetics of the resulting population—especially when a species was only waning rather than near its curtain call. In these cases, there might be the potential to act earlier, with a different risk-reward calculus at stake.

Sarah joined Funk’s lab in 2010 to try to answer this question by studying Trinidadian guppies. Evolutionary biologists had noticed that the paper-clip-size fish living at a stream’s headwater looked and acted differently than those at the end due to differences in the number of predators. What’s more, in many streams, the guppies at the headwaters had become isolated from their downstream brethren, and their numbers seemed to be slowly declining. Slogging through Trinidad’s rainforests, researchers moved a small number of downstream guppies upriver, and Sarah studied the effects of the new guppies on the resulting headwater population guppy boom. Importantly, Sarah showed that the genes from the downstream fish didn’t overpower the hybrid offsprings’ ability to survive in the headwater environment. This offered the best of both worlds: increased genetic variety, while maintaining headwater specificity. The work, Funk says, showed not just whether but how genetic rescue could work in the wild.

Sarah started her own lab at Michigan State University a year after Chen published her preliminary genetics studies. To Chen and John Fitzpatrick, it was becoming clear that the scrub-jays could benefit from such an experiment. Although Sarah preferred fish to birds, she didn’t hesitate to return to her roots. Seeing an opportunity to apply her work, she, Chen, and her dad decided to collaborate to save the species that once perched on her head.

The research at Archbold provided an invaluable baseline: It offered a chance to understand how the genetic rescue process might work for the species, gene by gene. The data also supported Chen and Sarah’s assertion that they wouldn’t need to move hundreds of birds to JD to see a benefit; even a few families should provide a solid genetic boost to small, isolated groups. If they are successful, Sarah hopes their work could help conservation biologists consider the tactic in more cases. Funk, Sarah’s former Ph.D. adviser, agrees: “This is probably one of the best systems in the world to understand genetic rescue,” he says.

Finding a donor population was easy. Miller had been banding and monitoring the birds at Ocala since 2014. Over that time, he had moved 49 jays from the national forest, home of more than one-third of the species, to bolster the birds’ numbers in nearby parks and had seen it hadn’t harmed the Ocala population. The bigger question was where to put them. An ambitious new fire-management program at JD had opened acres of perfect habitat, leaving room for newcomers. Miller and John hammered out how to select the émigrés and where to release them in the park. The researchers wanted healthy birds that had raised at least one fledgling, which would indicate their skill as parents and their genetic health. Since scrub-jays lived as families, they’d move them together.

In early 2019 the researchers moved a first family group, a total of three birds, from Ocala to JD, where there were fewer than 25 families left. That group did not successfully breed that year, something that Sarah and Miller expected might result from the stress of the move. But one breeding female either died or left the park between June 2019 and January 2020. The now single male was then spotted with a solo female at JD, making the team optimistic that the new, mixed pair might breed. The sign was encouraging enough that by January 2020, Miller, Sarah, and John thought it was time to try again.

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ehr and Sarah climb a low rise at JD, binoculars at the ready, with Miller on their tail. In the trio’s laser focus on the scrub, an impenetrable snarl of cacti and cabbage palms, they almost miss the scrub-jay pair from Ocala doubling back, turning northwest on a short flight over the release site and onto a sand pine snag.

The team regroups in a clearing 20 feet behind the birds, while an Eastern Phoebe watches on. Miller appraises them, his round tortoiseshell glasses giving him an owlish look as he scratches at stubble from his 4 a.m. wakeup time. For several hours they watch the Ocala pair bounce between the snag and nearby scrub oaks, calling back and forth. Then the birds hop to the ground and fall silent—a siesta to escape the pounding sun.