vacuolar myelinopathy is a neurological disease most commonly seen in bird species such as eagles and coots. the brains of the infected organisms develop lesions in the white matter of the nervous system, causing a loss of motor function. mortuary circles call this “swiss cheese brain.”

from its first recorded instance near degray lake in arkansas during the winter of 1994-1995, researchers, including aquatic scientist susan wilde, conducted field and laboratory studies to determine how species contract this disease. through laboratory and field experimentation, wilde and her team have recently concluded that a toxin produced by cyanobacteria is growing on invasive plant species within water bodies in the southeastern united states.

wilde, an associate professor at the university of georgia, worked with an international team from various scientific backgrounds. their findings, published in science, discovered the epiphytic cyanobacteria (aetokthonos hydrillicola) grow on hydrilla verticillata, a non-native plant species found in bodies of water. wildlife, such as fish, birds, and amphibians, eat these plants and consume the neurotoxin that leads to vacuolar myelinopathy.

vacuolar myelinopathy is not limited to the waterfowl that feed on these plants, explained anton j. reiner, a professor of anatomy and neurobiology at the university of tennessee health science center.

“it’s not a uniquely avian brain disease. it winds up looking like a uniquely avian brain disease because you have to consume a lot of it,” said reiner.

vacuolar myelinopathy also affects fish and amphibians that end up eating these cyanobacteria-infected invasive plants. fish, amphibians and waterfowl that feed on hydrilla become infected with vacuolar myelinopathy. higher-level predators such as coots and eagles consume the smaller animals, thus continuing the spread of the disease throughout the entire food web.

“so-called ‘apex predators’ like eagles, for example, wind up being especially susceptible to [vacuolar myelinopathy] because of their diet,”reiner said.

the disease manifests approximately five days after exposure when clinical signs of loss of motor control function become visible in avian species like eagles and coots. infected coots will float on the surface of the water on their backs and spin in circles, making them easy prey for eagles and other large avian predators. infected eagles will sit on tree branches with their wings drooping downward. according to reiner, there are instances of eagles flying into the sides of mountains while infected with vacuolar myelinopathy.

“every eagle i’ve ever seen with symptoms [of vacuolar myelinopathy] has died,” said william bowerman, professor and chair of the department of environmental science & technology at the university of maryland.

bowerman is a long-time collaborator of wilde’s on vacuolar myelinopathy, and his current research revolves around eagles as indicators of climate change and contaminants around the great lakes. he explained that birds are quality gauges of how the environment responds to various stressors, so the conservation of avian species from vacuolar myelinopathy impacts everyone.

“[vacuolar myelinopathy] killed tens of thousands of waterfowl and over 100 bald eagles. so, it’s a new, emerging disease, and it could be linked to pollution and also may be somewhat of an indicator of climate change,” said bowerman.

wilde and her team discuss spreading awareness and advocacy as a means to combat vacuolar myelinopathy in their recently published research. early in the paper, they state that the shift from the previous name of the neurological disease, “avian vacuolar myelinopathy,” to its current title “vacuolar myelinopathy” is necessary as it is not only limited to avian species. wilde and her team state that they are not yet sure of the potential impact vacuolar myelinopathy has on humans and recommend that further research be conducted.

“we want people to know the lakes where this disease has been documented and to use caution in consuming birds and fish from these lakes,” wilde told the american association for the advancement of science.

while there is still plenty of research to be done on vacuolar myelinopathy, wilde and her team’s discovery of the link between the cyanobacterial toxins and the lethal neurological disorder helps lie to rest the source of the perplexing avian deaths. bowerman hopes that wilde’s work will serve as a reminder of the importance of conserving a clean environment.

“it’s just important to understand that our organisms in the environment tell us what’s going on,” bowerman said. “if the birds and the mammals are healthy, then people are healthy.”

there’s something about bald eagles. yes, they are our national bird and their symbology pervades our culture in many ways and places. but there’s something more to them. if you’re like me, every time you see one, you just feel compelled to stop and look. they’re gregarious, powerful, and gorgeous birds. to the haudenosaunee, they are one of the most sacred beings that lives on this earth, a messenger to the creator. in the logo of the confederacy, a bald eagle sits at the very top of a large white pine. from there, it is the protector of peace, overseeing the nations and alerting them to any dangers that approach.

i first saw a bald eagle while kayaking along the chemung river near my home in the southern tier of new york. i was awestruck as it sat perched at the very top of a large dead tree, looking down at me, probably wondering why i had to be so rude as to scare away its lunch. it eventually took off soaring downstream before finding a thermal along the hillside, rising and disappearing high above me. today there’s a good chance of catching sight of at least one bald eagle along the river during the summer, and during the winter so long as the water remains open, i’ve seen adults and juveniles lurking right downtown in elmira. they’ve even begun to be seen again at one of the most sacred places to the haudenosaunee people, and once known as the most polluted lake in the country, onondaga lake. these occurrences seem to me already taken for granted, with remarks such as a scoffed ‘oh i see them around almost every morning,’ even at our local wild birds unlimited. how quickly we can forget.

historically, before the explosion in human population, industrialism, and development, there was a healthy bald eagle population in new york state. by 1970 however, there was a single pair of nesting bald eagles within the entire state. the two spent their summers on hemlock lake, an isolated lake in the western part of new york’s finger lakes, trying to raise eaglets, but because of chemicals in their tissues such as ddt, the eggs’ shells were too thin and fragile and would continually break early. after the national ban on ddt in 1972, the bipartisanly passed amendments to the endangered species act in 1973, and the beginning of new york’s endangered species program in 1976, the state department of environmental conservation began work on an intensive reintroduction of bald eagles into the state. using an ancient falconry technique known as hacking, the state successfully released 23 eagles in the first five years of the program at the montezuma national wildlife refuge, working closely with the us fish and wildlife service as well as the cornell lab of ornithology. after the testing proved fruitful, a goal of 10 breeding pairs in the state was set and large scale hacking began. by 1989, just 13 years after it started, the goal was met and the restoration program ended. during these 13 years, a total of 198 eaglets were released, roughly 15 birds each year. there were many hours logged by many dedicated people to make this a reality. as of 2010, there were 192 nesting pairs of bald eagles in new york, with 139 of them being successful, and fledging 244 offspring. that’s a 19,100% increase in the total number of breeding pairs, a 13,900% increase in those that were successful, and a 24,400% increase in eaglets over a roughly 40 year span since the time that there was only one pair, with no young.

in 1979, the public-private partnership of the mid-winter national bald eagle survey began to collect data about the numbers of individuals that were spending their winters in the u.s, as well as the habitats that they were using. the first winter survey in new york during ’79 resulted with 41 eagles counted. by 1990, that number had risen to 105; by 2000, 350; and ten years later in 2010, there were 658 bald eagles counted in the winter. during january of this year, as federal, state, and non-profit employees, as well as hundreds of other citizen scientist volunteers participated in the 39th annual survey, i decided to do the same. i assisted those at the montezuma wetlands complex and we tallied 44 bald eagles in our area of new york, with my partner and i contributing 2 to that number. undoubtedly though, the best part of my survey was the route that i was given. our official route ended at the top of a ridge, and as we got out of the truck to stretch our legs and scan for any signs of those iconic birds, we came to the mutual agreement to briefly deviate from our route ever so slightly. we made our way down an old path along the ridge that was beginning to become quite overgrown, and there at the end in a clearing was the tower that housed the first little eaglets that were ever hacked in north america. it was right there that the entire restoration of bald eagles in new york began.

in 2007, bald eagles were removed from the federal endangered species list, but today they remain listed as threatened in new york state. they can be seen all across the state, but their presence should be appreciated and not taken for granted. they continue to face a host of threats from many angles. lead poisoning from angling equipment in fish eaten and hunting ammunition in carrion consumed, continues to pose a large threat to bald eagles. strikes with wind turbine blades and trains also is a concern for the foreseeable future, though continued monitoring of populations by dedicated biologists, as well as the mid-winter surveys, will assist in appropriate sighting of renewable projects to minimize deaths. urban sprawl and the subsequent suburbanization, fragmentation, and habitat disruption, will also continue to pressure the population of bald eagles. as quickly as these magnificent birds returned to the state, and the country, they could disappear again just as rapidly. however, with continued collaboration on multiple levels, education about their importance and vulnerabilities, along with the preservation of open spaces and undisturbed habitats, as well as managing and restoring those that have been degraded, will provide the resources that these birds need and consequently, many more species will benefit, including our own.

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sources: data from the new york state bald eagle report 2010, p. nye, new york state department of environmental conservation. http://www.dec.ny.gov/docs/wildlife_pdf/baea2010.pdf