In 2014, we sent reporters to the islets of Iceland, the prairies of Canada, the shores of Lake Michigan and the backyards of Alaska, among other places, to reveal surprising new threats to the world's birds.
"Canary in the coalmine" isn't just a proverb: Birds are showing us what ails their environment – and sometimes, what ails us. Their nesting, their parenting, their brains, their hormones – even their songs – have been altered by pollutants, climate change and other threats. More than 1,300 species of birds are perched perilously on a global list of threatened species, and each one is sending us warnings that scientists are trying to decipher. Unfolding over six weeks, Winged Warnings was published in conjunction with National Geographic .
Built for survival
Birds are sending us messages about our own health and the health of the planet. They have long been indicator species for what ails the world. Birds are jeopardized from pole to pole.
Osprey whisperers
Listening to these birds of prey, which are the ultimate fish-eating locavores, has helped scientists identify environmental and human health threats for decades. Dioxins, DDT, flame retardants. What are these birds telling us now?
Empty nests of the North
Colonies of seabirds such as puffins, terns and kittiwakes are shrinking in the North Atlantic. Scientists are finding horrific scenes of dead chicks. The causes are poorly understood, but are inexorably tied to ocean health, especially climate change.
Heavy metal songs
Mercury alters the very thing that backyard birds are known for: their songs. Scientists stumbled across this discovery while listening to wrens and sparrows in a rural Virginia woods polluted by a chemical plant.
Poisoned
The bittersweet tale of a lead-poisoned bald eagle in Wyoming is a story about resilience – of birds and their healers.
Toxic gulls
Flame retardants are the 21st century's PCBs, and Great Lakes birds still are the victims. These chemicals in the gulls of Deslauriers Island off Montreal are altering their hormones. In kestrels, they are causing aggressive behavior.
Loss of night
Constantly being exposed to artificial light stresses urban birds, altering their behavior, hormones and mating. Scientists worry that this loss of darkness is changing birds' fundamental physiology.
Loon, interrupted
A mysterious drop in loons' chick survival is jeopardizing their comeback. Scientists are investigating this from Massachusetts to Montana. Could acid rain – that scourge of the '70s and '80s – be the cause?
Metal madness
Low levels of lead are dumbing down birds' instincts, altering their behavior and messing up their digestion. They may even be more prone to flying into power lines because they ate traces of brain- altering lead.
Twisted beaks
What is causing the deformed, macaroni-shaped beaks of Alaska's tiny chickadees, leaving so many of them to starve? Scientists have new clues. A similar condition has been found in other species in southeast Alaska, including 17 percent of captured crows.
Mass murder by botulism
Botulism, one of the deadliest toxins on Earth, is concentrating in exotic species, accelerating the threat to waterfowl and worsening die-offs in the Great Lakes.
Scrambling birds' brains
Eagles, coots and mallards are suffering a mysterious brain disease, largely in the Southeastern U.S., linked to a toxin in their food. Researchers are unraveling clues that could help find the causes of human neurological diseases, too.
A new generation of scientists
A look at the hazards of new neonicotinoid pesticides through the eyes of Canadian scientist Christy Morrissey. The endless cycle of one chemical replacing another drives the need for a new generation of vigilant scientists to replace Rachel Carson.
A perilous journey
We track the sooty shearwater's perilous 40,000-mile migration from south of New Zealand to the North Pacific and back. This seabird, which inspired Hitchcock's The Birds when it was poisoned with a brain-scrambling toxin, encounters a multitude of threats.
Opinion: The Lakota soar with the eagles
Being honored with eagle feathers pushes our tribe to better the people, not just the individual. Oyate kin yanipi kte lo . "So that the people will live." Not just our people, but also the wild creatures that have embodied our best values.
Opinion: Heed the nightingale's song
Looking forward means looking back and listening to what birds are telling us. Heeding their warnings gives us hope that their songs will endure.
Prologue: Robins dying in a mid-Michigan town
A neighborhood's songbirds are being poisoned by DDT, a pesticide that was banned in the United States more than 40 years ago.
Prologue: Experts question EPA's handling of bird-killing site
Health experts are questioning the Environmental Protection Agency and Michigan state officials for their decades-long delays in cleanup of a Superfund site that is killing songbirds in yards, possibly leaving people at risk, too.
Continuing coverage: Good for the gander? As Alaska warms,a goose forgoes a 3,300-mile migration
Virtually every Pacific black brant – about 160,000 birds – is gathered now in a remote corner of Alaska, feasting on the most extensive eelgrass beds on Earth. This was just a stopover in the brant's autumn journey to Mexico. But nature no longer follows that predictable course.
