CSI: Wildlife — Solving Mysterious Animal Deaths
Carol Meteyer solves cases of mysterious wildlife death using advanced forensic skills to help prosecute people who kill animals in violation of federal law.
Carol Meteyer unfurled the Sandhill crane's gray wings across the steel examination table, and for a moment, the 4-foot-tall bird regained its former majesty. In that instant, the laboratory's windowless cinderblock walls, cement floor and fluorescent lights disappeared. It was easy to imagine the crane's wings cupping the prairie air as it landed in an Oklahoma field, its long gray neck stretched, its red crown the only bright spot in a dun landscape.
FedEx had delivered the crane, along with three others, that morning. The day before, it had stood in a farm field in Oklahoma, its head bowed and its wings limp; 10 other cranes were already dead or showing similar symptoms.
Dead animals arrive at the National Wildlife Health Center in Madison, Wis., almost every day, usually by overnight delivery in plastic coolers. State and federal wildlife biologists from all over the country send carcasses to the lab hoping to solve cases of mysterious animal deaths, to confirm their own diagnoses or to provide evidence in legal cases against an animal's killer. Because it does solve animal murder mysteries through scientific investigation, the center has been called wildlife's own CSI unit. It would be just as accurate, though, to call it a wildlife Centers for Disease Control and Prevention. The CDC also solves deadly mysteries, but the emphasis there, as at the wildlife health center, is on research, outreach and prevention of needless death.
Slim, blond, dressed in a blue paper gown over hospital scrubs and wearing a surgical mask, the 57-year-old Meteyer could easily pass for one of her fictional crime-solving counterparts, except for the knee-high rubber boots she wears like the veterinarian she is. Gently probing the crane with purple-gloved hands, Meteyer feels swelling in its neck and swabs the bird's feathers with a scrub brush dipped in a detergent-and-antiseptic solution. Then, she sharpens a large knife and slices the crane open from throat to belly, examining its skin and its ribs and snipping off the rib cage with heavy surgical scissors.
The crane's spleen is twice as big as it should be, and it's dark red. "I think we are going to have a diagnosis here," Meteyer says. From the moment she heard "crane" and "farm field," she suspected that the cranes were felled by one of the fungal toxins, known as mycotoxins, that plague peanuts, corn and other crops. When this type of fungus strikes, the crop becomes poisonous, and because it can't be sold, farmers too often leave it standing in the field, creating a fatal attraction for wildlife. The mystery for Meteyer is which mycotoxin is responsible. So far the evidence — the swollen neck, a white-spotted kidney, the enlarged spleen and syrupy bile — points to three different possible perpetrators.
Meteyer drops bits of the crane's heart, spleen and other organs into a jar of formalin, which preserves the tissues until they are sliced and placed on microscope slides for her to examine another day. She cuts open the crane's stomach and with a plastic spoon scoops out what looks like ground peanuts, corn and bits of grass. One of the center's microbiologists will culture the stomach contents to see if a toxic fungus grows. Meteyer hopes that either the culture or the microscope will reveal the culprit.
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Meteyer grew up in Illinois and Iowa, spending her days roaming fields and exploring streams. In second grade, she found a toad with a broken leg and decided that it needed to keep still so it could heal. She buried the toad in a shallow hole. When she dug it out three weeks later, it hopped away.
Becoming a veterinarian was always her dream, but after college at the University of Iowa, she found herself teaching high school science. Afraid that the dream was slipping away, one day she signed up for a class in engineering physics, the only course she could take at night while continuing to teach. Along the way, she spent the savings from her teacher's salary on a horse, a horse that was terrified of trailers. When she began veterinary school at Iowa State University the next school year, she rode the horse 130 miles to its new stable in Ames, bunking with farm families as she traveled.
Still a healer of toads at heart, Meteyer began an exotic animal club at the vet school. As a veterinary intern in California, Meteyer was gentle, concerned with not causing her patients any additional pain and empathizing with their owners' worry. Compared to the emotionally draining work of helping sick animals and their heartbroken owners, Meteyer found her visits to the veterinary pathology lab peaceful. There, she found herself drawn to the pastel-stained world of microscope slides. Meteyer wasn't sure she was doing the right thing by leaving the world of living animals, but each heartrending shift as a relief veterinarian assured her that pathology was the better path.
As a veterinary pathologist, it's possible to spend most of your days diagnosing cancer in cats and dogs. Meteyer considered herself lucky, during her residency in Los Angeles, to work on animals from Marineland of the Pacific and horses from the local racetracks, and to test wild wolves for plague. After her residency, she diagnosed the diseases of chickens and turkeys for the poultry industry at the University of California, Davis, where she occasionally saw animals from Fresno's zoo.
A friend told her about what she was sure would be Meteyer's dream job: a wildlife pathologist at the National Wildlife Health Lab. Meteyer thought it a dream job, too, but turned down the lab's offer because she was eight months pregnant with the first of two daughters. However, the job was still open when her maternity leave was over.
As they grew up, her daughters told their friends that their mom cut up dead things for a living. "They think I'm a sweet nerd," she says. They're now in college.
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Along with three fellow wildlife pathologists at the National Wildlife Health Center, Meteyer defines what is normal in wildlife health across the United States and what new patterns of disease and poisoning require the attention of wildlife managers and researchers. She has helped uncover such patterns in regard to white-nose syndrome in bats, abnormalities in frogs, pharmaceutical poisoning in vultures and countless lesser mysteries. Her tools are a scalpel, wielded in a type of animal autopsy called a necropsy, and a microscope.
"When I look through a microscope, I feel so privileged to have that view," Meteyer says. "I have to communicate that to the people who work with the animal." For Meteyer, that not only means the expected report to the wildlife biologist who asked for the lab's help, but also writing journal articles, preparing field guides and speaking at conferences about her findings.
"She very much gets why she is here: to help the people in the field." says Scott Wright, chief of the center's disease investigations branch and Meteyer's boss. "Still, she makes the most she can out of the science." Although not an academic, Meteyer has been an author or co-author of more than 40 peer-reviewed scientific papers. Wright recently helped promote her to a research-grade position. "Carol has her share of discoveries and is well respected because of her experience," he says.
As Meteyer worked on the crane, two technicians worked at another examination table. They had spread out two dozen blackbirds from the headline-grabbing New Year's Eve "Aflockolypse" in Beebe, Ark. Some 5,000 blackbirds out of a flock of a million died that New Year's Eve, after fireworks exploded near their roost. Shortly afterward, a sample of the dead birds was sent to the center for analysis.
One pathologist performed more than 40 necropsies on the birds, finding a similar pattern of trauma in each one. The pathologist's findings were conclusive but unpopular: The birds were startled and died after flying into buildings and power lines. The lab's other pathologists, including Meteyer, answered phone calls from the media and curiosity seekers. While the media interest had moved on, the center continued to analyze the incident. The technicians were swabbing the birds for an avian cholera test.
This was not the first time the National Wildlife Health Center's investigations had been in the public eye. Spurred by the death of 40,000 ducks from duck plague in South Dakota, the lab has helped unravel the mysteries of West Nile virus, chronic wasting disease in deer, waterfowl poisoning by lead shot and monkeypox virus in exotic pets.
At its founding in 1975, the lab was a part of the U.S. Fish and Wildlife Service, a regulatory agency, and in 1996 became a part of the U.S. Geological Survey, which doesn't have federal regulatory authority. But that doesn't mean the wildlife lab's investigations are toothless. The center houses scientists with expertise in viruses, bacteria, fungi, parasites, biochemistry, ecology, veterinary medicine and pathology, and they investigate violations of federal wildlife laws, including the Endangered Species Act, the Migratory Bird Treaty Act and the Bald and Golden Eagle Protection Act.
The U.S. Fish and Wildlife Service has its own lab in Ashland, Ore., dedicated to wildlife forensics. Meteyer sees the forensics laboratory's expertise as analyzing animal DNA and identifying animals from body parts in smuggling cases; the Wildlife Health Center's legal role focuses on determining whether the cause of death was natural or from human activity. Meteyer's legal cases have included birds that were poisoned by cyanide at a silver mine and endangered wood storks poisoned by pesticides.
Meteyer was in the first half of her nearly two-decade tenure at the lab when abnormal frogs began arriving from Minnesota, Maine, Wisconsin and Vermont. Some had too many legs or toes, others too few. In some locations, 60 percent of the frogs were deformed. Was the thinning ozone layer zapping the frogs with ultraviolet rays? Were pesticides poisoning them? Would we be next?
Meteyer X-rayed the frogs and found that their bones provided valuable clues. Bones in limbs that had been bitten off by a predator when the frog was an adult looked different than locations where a budding leg had been bitten off a tadpole. True malformations — the frog equivalent of a birth defect — looked different from either of these. She put the frog X-rays together, along with a glossary describing the abnormalities, into the "Field Guide of Malformations in Frogs and Toads," which is still used by researchers deciphering new clusters of frog abnormalities. With good information available about the causes of the frog abnormalities, many of them natural, public panic subsided.
And when white-nose syndrome first struck bats in the Northeast four years ago, Meteyer found herself among only a handful of pathologists who believed the powdery white fungus on the bats' skin was the cause of their death. When she examined microscope slides of the affected bats' wing tissues, she saw that the fungus was penetrating the lower, living layers of skin, and the skin reacted by swelling. It was a clear sign that the fungus was attacking living bats and not an opportunistic infection that came later.
Meteyer was a co-author on the paper that announced the white-nose syndrome fungus. She published the physical description of white-nose syndrome — both what it looks like during a necropsy, and what the bat's tissues look like under a microscope — that is used by other pathologists to diagnose new cases of white-nose syndrome.
But unlike casts of the various CSI shows, the Wildlife Health Center staff can't solve every case in an hour, or even a career. Meteyer is still haunted by a bird syndrome called avian vacuolar myelinopathy. When she first started working at the lab, she received American coots, a ducklike bird, and the occasional bald eagle found on Southern lakes. Some were found dead; others were blind and convulsing. Meteyer identified the distinct brain lesion that identifies the syndrome 17 years ago, and birds with the syndrome are still diagnosed at the lab, usually arriving between Thanksgiving and Groundhog Day. But Meteyer has been unable to isolate the biotoxin, possibly produced by algae, that she believes is responsible.
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About a week after the Sandhill crane necropsy, Meteyer received slides of tissue samples. Looking through the microscope in her office, Meteyer entered a world of pink-, blue- and purple-stained cells. She examined a crane kidney that appeared pale and swollen on the examination table and saw no evidence of kidney disease. That eliminated one of the rarer mycotoxins from the list of suspects. The red spots on one of the cranes' livers were revealed, under the microscope, to be bleeding from damaged blood vessels, not dead tissue with blocked vessels. That crossed another mycotoxin off. The cranes' small blood vessels, however, were a mess, dead and clotted with blood.
The toxics tests and the stomach content cultures all came back negative, so Meteyer had to rely on her own observations and experience as she put together her report. The swelling in the cranes' necks, their internal bleeding and the clots in their small blood vessels all suggested to Meteyer that the cranes died of trichothecene poisoning. That the cranes were eating peanuts was an important clue. "Peanuts are the usual source for the Fusarium fungus," she says. And Fusarium produces trichothecene.
In Oklahoma, the farm field where the dead cranes were found had since been seeded with wheat. During planting, at the request of the biologist who'd sent the cranes for testing, the farmer had plowed the fungus-infested peanuts deeply into the ground, burying the mycotoxin they contained. Back in Madison, Meteyer was excited to hear what had happened. "That is what we are here for," she said as the case of the poisoned Sandhill cranes came to a close. "It's what brings meaning and relevance to what we do."