West Nile Virus Has Killed Millions of U.S. Birds, Is Lethal for Humans and Is Increasing Again… A new Pandemic Ahead?

The West Nile virus has killed millions of U.S. birds…

The virus, also deadly to humans, continues to spread among birds… And back in 1999, many expected the virus to race through the human population as a pandemic, but the disease peaked four years later with just under 10,000 cases nationwide. The fear waned. What about now?

Chief, a white-and-orange English setter, knifes through a forest of pale-barked aspen, so thick in places the trees seem to gobble him up, the ding ding ding of his collar the only clue to his whereabouts.

These impenetrable thickets in central Pennsylvania known as the Scotia Barrens make for hard hiking. But they’re prime habitat for ruffed grouse — crow-size birds whose mottled, russet coloring blends into the fallen leaves Chief is sniffing feverishly. If he flushes out a ruffed grouse on this November afternoon, he’ll get an extra hearty pat from his owner, Lisa Williams. That’s because Pennsylvania’s official state bird is getting harder to find.

“Depending on who you talk to, the ruffed grouse is either the king of the game birds, or it’s a forest chicken,” says Williams, grouse biologist for the Pennsylvania Game Commission, a state agency whose mission is to conserve birds and mammals for present and future generations. Hunters prize ruffed grouse because they’re canny — elusive on the ground and tricky targets in the air.

They’re native to the Appalachian and Rocky Mountains, the Great Lakes region, and large swaths of Canada. In the spring mating season, males hop onto a log and beat their wings rapidly and rhythmically in a crescendoing womp womp womp — “drumming” that carries more than a quarter of a mile, even through thick cover such as we’re tromping through following Chief’s helter-skelter lead.

But after a few hours of searching, the setter comes up short.

Between 1978 and 2000, flush rates for ruffed grouse reported by hunters in Pennsylvania declined by 2 percent, reflecting the aging of the thick, young forests the birds need for food and shelter, Williams says. But then, between 2001 and the end of 2018, flush rates plummeted by 54 percent.

The culprit?

West Nile virus: a mosquito-borne pathogen that dominated the news when it appeared in New York City in the summer of 1999. Many expected the virus to race through the human population as a pandemic, but the disease peaked four years later with just under 10,000 cases nationwide. The fear waned.

The virus lingered in the woods, however, spreading from bird to bird — not just ruffed grouse but more than 300 species, causing brain lesions, and killing millions of birds. “Some of our best-loved backyard birds are missing,” Williams says. Crows, owls, and blue jays are among those that have suffered severe losses to West Nile virus. Ruffed grouse numbers have fallen in states from Minnesota and Michigan to North Carolina and New Jersey, a problem exacerbated by climate change.

In Pennsylvania, Williams says, ruffed grouse declined by an estimated 23 percent between 2017 and 2018 —­ “a horrendous year.” West Nile virus, she adds, is “a classic climate change disease.” Earlier springs in the forests give mosquitoes more time to pump out larvae, and increases in precipitation, also spurred by climate change, create more stagnant pools in which the insects can reproduce.

For all the seriousness of the situation, ruffed grouse numbers have yet to fall to a level that would trigger Endangered Species Act protections. That’s all the more reason to act now, Williams says. “The time to intervene is before you’re in that emergency-room situation. You want to do something while you still have enough animals to respond and work with.”

Following a hunch

Williams spent nearly two decades as a bat expert at the Pennsylvania Game Commission before switching to ruffed grouse in 2011. She had witnessed firsthand how white nose syndrome, a fungus that infects the faces and wings of bats, devastated local bat populations, and the more she examined ruffed grouse population information, the more she suspected that something similar was happening to the birds. But no one could say for sure, because in the early years after the virus showed up, most research focused on human health. (Read more about the killer fungus wreaking havoc on bats.)

In 2004, for example, Pennsylvania’s largest breeder of captive grouse reported that 24 out of 30 birds died during a two-week period. This prompted him to send one of the dead birds to a lab for testing, which determined West Nile virus as the cause of death. In 2005, a biologist found West Nile antibodies in birds killed at the Annual National Grouse and Woodcock Hunt, in north-central Minnesota. In 2006, experiments showed that West Nile could be particularly lethal to greater sage grouse, a relative of ruffed grouse native to the American West.

“There were all these different things that came together as I was sort of working through this hunch,” Williams says.

To get a better idea of what was going on, Williams mined information provided by hunters — an “amazing” trove going back to 1965. In Pennsylvania, ruffed grouse hunts are permitted from mid-October to the end of November, as well as for another 10 days in mid-to-late December. Each hunter is allowed to take up to two grouse a day but isn’t permitted to have more than six in the freezer at one time to prevent overexploitation of the birds.

In November 2019, I joined Duane Diefenbach, a wildlife ecologist with the U.S. Geological Survey, and his English setter Chelsea, in Susquehannock State Forest, in north-central Pennsylvania. Diefenbach is one of hundreds of hunters who report to the commission everything from the number of hours they spend looking for grouse and where they search to how many times their dogs flush out birds.

When cornered, a ruffed grouse explodes out of the forest undergrowth with thunderclapping wings. So when Chelsea freezes, signaling that she’s scented a grouse, Diefenbach closes in, shotgun poised. But no bird erupts. “This is probably where the grouse was 10 minutes ago,” he says ruefully.

By the end of our outing, though, Chelsea and a younger setter named Parker have flushed out eight grouse. Diefenbach doesn’t bag a single one, though. “That’s how it goes with grouse hunting,” he says with a grin.

This eagle was released a few weeks ago after being attecked by the West Nile Virus:

Eight ruffed grouse may seem a good number, but 30 years ago, a day in this forest would likely have yielded 20 or so, according to Diefenbach. “Everyone I know agrees there’s fewer grouse, and that’s because there’s less habitat…but if you’re a dedicated grouse hunter, you know that the changes over the past 10 years have nothing to do with habitat.”

To get a deeper understanding of the effects of West Nile virus on ruffed grouse, in 2014 Williams began asking hunters to mail in feathers and blood samples, which she tested for the disease. Counterintuitively, she says, in a bad West Nile year, only about 4 percent of hunted birds have antibodies that indicate previous West Nile infection. But in years when West Nile ebbs, up to a quarter of the hunted birds may test positive for antibodies. That’s because when the virus is hitting hard, exposed grouse don’t survive long enough to be shot by hunters in the fall.

Williams says this suggests that the virus’s true toll is likely even higher, because there’s no way to estimate how many ruffed grouse die from it before the hunting season begins.

Millions of bats killed by mysterious fungus in the USA

Fighting back

Since 2014, states from Minnesota to Maine and North Carolina have followed Pennsylvania’s example and collected ruffed grouse blood samples. Most places register declines similar to Pennsylvania’s, but Maine, inexplicably, seems largely unaffected. This could be because most hunting — and 98 percent of the testing — takes place in the northern part of the state where the climate is generally cooler, says Kelsey Sullivan, migratory bird biologist at Maine’s Department of Inland Fisheries and Wildlife. Or, he adds, it could be “that quality habitats reduce occurrence and increase the ability of grouse to withstand and diffuse the virus.” And Maine’s north woods are as close to paradise for ruffed grouse as it gets.

Lisa Williams has been pushing the importance of habitat for a while. And in 2019, she teamed up with Bob Blystone and Jeremy Diehl, geographic information system analysts at the Pennsylvania Game Commission, to develop a computer model to assess habitat quality. It’s called the Grouse Priority Area Siting Tool (G-PAST), and it can help wildlife managers identify the best and worst areas for conserving ruffed grouse.

G-PAST predicts, for example, that the Scotia Barrens — previously some of the best ruffed grouse habitat in the state — is unlikely to regain that status region-wide because of its low elevation (where mosquitoes tend to thrive), its flat terrain (conducive to standing water where mosquitoes breed), and its lack of proximity to existing grouse populations (which hold potential for repopulating the area). By contrast, G-PAST finds that parts of Susquehannock State Forest, where the terrain is higher, could serve as critical ruffed grouse sanctuaries.

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With that information, the Pennsylvania Game Commission can target forest areas for management strategies such as cutting stands of older trees to encourage the new growth preferred by ruffed grouse, which will also invigorate more than 30 other species, including deer, bears, turkeys, and rattlesnakes.

Another way to help grouse is by adjusting the pressures people put on them. New Jersey has banned ruffed grouse hunting indefinitely and is working with Pennsylvania to create its own version of G-PAST. Both Pennsylvania and Wisconsin have shortened their hunting seasons, and Ohio is considering doing the same. Hunters have been supportive of the measures.

“Grouse hunters are their own unique breed,” Williams says. “They’re highly passionate about the species, and they’re willing to give up their own recreation to try to help.”

Meanwhile, in coordination with hunters and other Great Lakes states, Minnesota’s Department of Natural Resources, based in Saint Paul, recently started a two-year study of West Nile virus in ruffed grouse. According to Charlotte Roy, the department’s grouse project leader, the state is experiencing more frequent extreme rainfall events, which may lead to more West Nile-carrying mosquitoes.

“I think we should be aware of the impacts that we’re having on natural processes and potentially take corrective action where we can,” she says. “West Nile virus is going to be out there whether we pay attention to it or not.”

So is this West Nile Virus the next pandemic? It has already killed millions of birds across the US and probably many more across the world… It is also lethal for humans and many expected the virus to race through the human population as a pandemic. Although the fear waned, we would of course not be prepared. More dead birds news on Strange Sounds and Steve Quayle. [NatGeo]

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