As if loons weren’t under enough pressure already in Minnesota and the upper Midwest, there’s a new threat driving down their numbers — mass botulism poisonings in the Great Lakes.
Driven by a complex interaction of invasive species and climate factors, not yet well understood, in which the deadly bacterium is carried through the food web by quagga mussels, round gobies and other non-native creatures, the toll has become significant.
During a couple of months in late 2012, more than 1,400 dead birds — mostly loons — washed ashore at Sleeping Bear Dunes on the east side of Lake Michigan. Another 4,300 birds have been counted there since then — some of them piping plovers, whose numbers in the region may be down to 70 nesting pairs. And that’s just a small piece of the picture:
Nonnative creatures have been driving a deadly surge in avian botulism in the Great Lakes over the past 15 years, killing an estimated 80,000 birds, including loons, ducks, gulls, cormorants and endangered piping plovers.
Now scientists are searching for what has triggered this change in intensity of the disease: If they can unravel where and why the lethal toxin is building up in food webs, they can predict which shorelines are death traps for birds.
Those excerpts are from this morning’s installment of “Winged Warnings,” a remarkable series on extinction threats to the world’s birds produced by Environmental Health News and co-published with National Geographic.
EHN is best known as comprehensive aggregator/curator of news related to the public-health side, especially, of environmental issues. But it also produces some original material, of which this 15-part series may be the high-water mark so far.
It’s getting surprisingly little attention in other media, though, and for me has proved easily overlooked in the daily torrent of environmental news. I’m a regular, even near-daily reader of EHN’s front page, and yet I managed to miss “Winged Warnings” utterly until a reader called it to my attention, following my post last week on two recent state-of-the-birds reports.
Those were sobering forecasts, without question, but heavily statistical and America-centric; their overlap with this series — global in scope, deeply reported, dramatic in its tales of struggle, both avian and human — is quite minimal.
Its key statistics:
- Some 1,300 bird species worldwide — about one in eight — face a significant risk of extinction today, and in most cases their situations are deteriorating.
- That compares to about 150 known extinctions of birds in the last five centuries, a rate that may accelerate tenfold by the end of this one.
- Even now, 197 bird species are in such dire circumstances that they’re considered to be just one serious epidemic or a couple of bad breeding seasons from their vanishing point.
This is all the more remarkable because birds are not especially frail — quite the opposite, actually:
Sole descendents of the dinosaurs, birds have penetrated nearly every ecosystem on Earth and then tailored their own size, habits and colors to each one, pollinating, dispersing seeds, controlling bugs, cleaning up carrion and fertilizing plants, all the while singing notes so beguiling that hearing them makes even the urban dweller pause to listen. Birds are the planet’s superheroes, built for survival.
Sturdy but not invincible
But their survival skills are increasingly overmatched by a series of potent challenges. Probably the main one in EHN’s focus is chemical pollution — alongside the familiar scourges of residual DDT and fresh lead dispensed by hunters and anglers are newer threats from flame retardants, prescription drugs, mercury and other heavy metals.
Then there is habitat loss, the creation of permanent daylight in some urban settings, the complex influence of shifting climate essentially everywhere:
In North America’s breadbasket, populations of grassland birds such as sweet-trilling meadowlarks are in a free-fall, along with those everywhere else on the planet. Graceful fliers like swifts and swallows that snap up insects on the wing are showing widespread declines in Europe and North America. Eagles, vultures and other raptors are on the wane throughout Africa. Colonies of sea birds such as murres and puffins on the North Atlantic are vanishing, and so are shorebirds, including red knots in the Western Hemisphere. Sandpipers, spoonbills, pelicans and storks, among the migratory birds dependent on the intertidal flats of Asia’s Yellow Sea, are under threat. Australian and South American parrots are struggling and some of the iconic penguins of Antarctica face starvation.
While birds sing, they also speak. Many of their declines are driven by the loss of places to live and breed – their marshes, rivers, forests and plains – or by diminished food supply. But more and more these days the birds are telling us about new threats to the environment and potentially human health in the coded language of biochemistry. Through analysis of the inner workings of birds’ cells, scientists have been deciphering increasingly urgent signals from ecosystems around the world.
Like the fabled canaries that miners once thrust into coal mines to check for poisonous gases, birds provide the starkest clues in the animal kingdom about whether humans, too, may be harmed by toxic substances. And they prophesy what might happen to us as the load of carbon-based, planet-warming gases in the atmosphere and oceans climbs ever higher.
And yet I would not call this a fundamentally gloomy report, in part because it works so hard to understand and demonstrate the human fascination with birds — which we have long observed more closely than any species except our own — on every level, from the instinctive to the aesthetic, from the scientific to the spiritual.
Some favorite excerpts from the series so far:
From Part 3, which focuses on the problems of puffins, Arctic terns and other birds in the far North Atlantic:
On the Westman Islands off Iceland’s south coast – home to the world’s largest Atlantic puffin colony – breeding has been a “total failure” since 2005, according to the South Iceland Nature Center. The impacts are being felt throughout the country, where these clown-faced birds have been both a legally-hunted delicacy and a national mascot. “Puffin watch” – news on how things are going in the burrows each summer – is as popular here as “volcano watch.”
Rising ocean temperatures are squeezing out the birds’ main prey, pencil-shaped fish called sandeel. For hundreds of years, sandeel were abundant in these waters, providing the intense nutrition chicks need for quick growth in the short northern summer.
Warmer waters seem to disrupt the sandeels’ growth by speeding up their metabolism, Hansen says. Plus, more southerly fish, like voracious mackerels, are moving in. Puffin parents must forage farther and come back with less – or less-nourishing – fish for their young. These days, chicks starve, nests are abandoned, and increasingly, birds don’t even bother to breed.
Translating of birdsong
From Part 4, on chemical-induced changes in birdsong, which is pretty to us but a survival need to them:
Cristol and Hallinger aren’t the only ones who have shown that contaminants are changing the songs that have inspired poets and musicians like Shakespeare and Handel. Around a smelter in northern Europe with a lot of heavy metal pollution, a study of birds found that they knew fewer songs and sang less at sunrise than birds at two less-polluted sites. One small study of Nelson’s sparrows at sites with high and low mercury in Maine found that their songs were measurably different, although they weren’t the same differences that Cristol’s group found. Last year another study showed that chickadees along the Hudson River exposed to polychlorinated biphenyls sing strange songs.
And from Part 7, on how “loss of night” is affecting birds in a growing portion of the urbanized world by suppressing sex hormones, among other impacts:
Around the world, scientists seeking to answer that question have gathered mounting evidence that city lights are altering the basic physiology of urban birds, suppressing their estrogen and testosterone and changing their singing, mating and feeding behaviors. One lab experiment showed that male blackbirds did not develop reproductive organs during the second year of exposure to continuous light at night.
People can suffer an array of health problems when they work night shifts that alter their circadian, or daily, cycles governed by a biological clock. In the wild, light pollution causes hatchling sea turtles to lose their way from beach to the ocean, and disorients Monarch butterflies searching for migration routes. In field experiments, Atlantic salmon swim at odd times, and frogs stop mating under skies glowing from stadium lights at football games. Millions of birds die from collisions with brightly lit communication towers, and migratory flocks are confused by signals gone awry.
Today’s installment was Part 11 in the series, with five more to come in September. Tell your friends.