The eagle may be America’s mascot, but being a bird today in the United States is tough. Billions die each year in the maws of domestic cats, or after crashing into power lines or skyscraper windows. But on a large scale, climate change is warping the environment of birds that migrate long distances, such as whooping cranes or Arctic terns. And bald eagles, the nation’s regal avatar, are being struck down by lead poisoning.

Bird conservationists are now alarmed by a fresh threat – the Trump administration. In a striking new stance on a longstanding law protecting migrating birds, the federal government will essentially allow the “incidental” killing of birds via buildings, energy production and other developments that act as avian death traps.

“Sadly, migratory birds have not faced this many dangers in any of our lifetimes,” said David O’Neill, chief conservation officer at the campaign and conservancy group Audubon. “The pressures of climate change coupled with the federal government pulling back on protections are threatening the songbirds, the seabirds and the raptors that Americans really cherish.”

Audubon, along with the attorneys general of eight states, recently launched a legal attempt to halt the Trump administration from reinterpreting the Migratory Bird Treaty Act, a 100-year-old law that safeguards about 1,000 migrating species, spanning everything from bluebirds and mockingbirds to ducks, owls and eagles. Nearly one in 10 of these species are federally listed as threatened.

Facebook Twitter Pinterest A long-eared owl. Photograph: Jed Wee/Rex Shutterstock

Until now, this law has prevented the intentional killing of these species while also requiring that industries ensure they take reasonable steps to prevent foreseeable, unintended harm, such as covering oil pits that birds mistake for water, restricting the use of some poisons or making electrical lines and wind turbines more visible to creatures on the wing.

But a new legal opinion for the Department of Interior has swept this aside. In December, Daniel Jorjani, the department’s principal deputy solicitor, wrote that the current set-up “hangs the sword of Damocles over a host of otherwise lawful and productive actions” and should be reversed. This could be read as: short of businesses actively handing shotguns to employees and ordering them to blast puffins or fork-tailed swifts from the sky, the law won’t intervene.

“The new opinion is that birds are no longer of consequence,” said Steve Holmer, vice-president of policy at the American Bird Conservancy. “It’s a carte blanche situation.” Even in an administration that has sought to loosen any restrictions on oil, gas and the coal industry, the decision stands out. O’Neill said: “It is beyond anyone why the administration would want to make it easier to remove these protections and kill birds.”

The creation and growth of cities, roads, power lines, factories and energy production across the US have taken a huge yet banal toll on birds. Domestic cats alone exterminate an average of 2.4 billion birds a year, mostly of the small, backyard variety, according to US Fish and Wildlife service statistics. Then there are the 600 million birds a year that perish across the US by thudding into glass-sided buildings and windows. A further 25 million a year die from hurtling into electrical lines, 72 million from poisoning.

Donald Trump pondered this enormous mortality on the campaign trail in 2016. “The wind kills all your birds,” he said at a rally. “All your birds, killed. You know, the environmentalists never talk about that.” In fact, wind turbines kill an average of 234,000 birds a year – a fraction of the overall 709 million finished off by all industrial activity in the US.

Like their terrestrial counterparts, birds also suffer from the loss of millions of acres of habitat a year due to housing development, agriculture and logging. The harm can also be indirect, such as when hawks and eagles feast upon prey that has been contaminated by human activity in various ways.

Trump’s interior department has removed bans on using lead ammunition and fishing tackle in wildlife refuges, contributing to reports of increasing lead poisoning in some birds of prey, including bald eagles, which have a celebrated conservation success story after nearly being wiped out in the 1960s due to the use of the pesticide DDT.

Excess lead can cause reproductive and cognitive problems in birds, sometimes causing them to plunge like malfunctioning aircraft into hazards like trains or towers. A new US Geological Survey report has found that around a quarter of all bald and golden eagles in the US have chronic lead exposure.

“We have seen an uptick in lead poisoning among bald eagles, which gives them convulsions and makes it hard for them to breathe,” said O’Neill. “Eventually they can’t digest food and they die. Bald eagles. These deaths are unnecessary and unconscionable.”

Facebook Twitter Pinterest Bald eagle. Photograph: Alamy Stock Photo

Many migrating birds that manage to avoid being directly slaughtered or maimed face a more attritional decline due to climate change. As landscapes warm up, birds are able to escape more easily to more tolerable climes than most land-dwelling species but the shifting of the seasons will prove critical.

Research published last week found that spring is arriving earlier in three-quarters of nearly 500 national wildlife refuges across the US, compared with an average over the past century.

The annual arrival of the first blooms and leaves is occurring faster at more northerly latitudes, as well as on the eastern seaboard – on the Atlantic “flyway”, stretching from Florida to the northern tip of Quebec, spring is now arriving 11 days earlier than the long-term average. In Alaska, colonies of thick-billed and common murres have been decimated, with unseasonal warmth affecting ocean food supply and blamed for the birds’ starvation.

Birds that spend their winter in the southern US or Mexico are arriving in their northern breeding grounds beyond the time when food such as plants and insects are at peak abundance.

“Birds pay attention to local conditions for their cue to move north,” said Theresa Crimmins of the USA National Phenology Network, a study co-author. “So if spring advances more rapidly in the north, they will miss out on available food. Once they get out of sync they risk diminished breeding success and numbers can significantly decline. Whole ecosystems can change. We are on the verge of seeing this.”

Even if global temperature increases are constrained over the course of the century, more than half of 588 US bird species will lose the majority of their current geographic range, an Audubon study has found. For 126 of these species, there will be no suitable environment for them to move into once their current area is denuded of food or simply becomes too hot.

“Take the whooping crane – its wintering area is very small in Texas, its breeding area is very small in Alberta,” said Eric Waller, a US Geological Survey scientist who worked on the climate research with Crimmins. “They don’t have a lot of wiggle room. If trends continue, it will be problematic. Birds are a nice case study for other migrating species. They are the canaries in the coalmine, if you will, for climate change.”