If you need proof that climate change has altered the wildlife of the city, look no further than the black vultures soaring above Midtown Manhattan. These hulking, baldheaded scavengers have a wingspan that measures nearly five feet and have traditionally inhabited South America, Central America and the southern United States.
But the black vulture seems to be here for the foreseeable future, along with 20 or 30 species that have recently expanded their ranges into New York City. As weather patterns have warped, and habitats have shrunk and food supplies diminished, the migratory patterns of birds have also changed.
“It would have been unheard-of,” said Andrew Farnsworth, a researcher at Cornell University’s Lab of Ornithology, to spot a black vulture in Manhattan 30 or 40 years ago. Now, more than 300 sightings have been recorded in the city since March 2022, according to the Cornell-managed citizen-science project eBird. Black vultures are moving north because of milder temperatures and the ability to scavenge in suburbs near the city, Dr. Farnsworth said. He estimated that as many as 30 new species have joined the more than 200 bird species that regularly spend time in the metro area.
Some birds have been harmed by all of the changes; others seem to be adapting. But in a delicately formed ecosystem, the presence of a new species or the disappearance of one can have cascading impacts across the whole habitat.
Species like the American robin and the Canada goose are relatively new to spending the winter around New York City, said David Wiedenfeld, a conservation scientist at the American Bird Conservancy. Because snow cover is less prevalent than it once was, these species can stay farther north and feed from the ground even in winter. The populations of both of these birds are growing.
In New York Harbor, wading birds like Herons and egrets now have fewer places to go, said Dustin Partridge, director of conservation science for the New York City Audubon Society.
The group has surveyed wading birds in the area since 1985, and has found that sea level rise, among other factors, may be shrinking the small islands dotting the habitat. In 2000, there were 15 active wading bird colonies in and around the harbor, according to city Audubon data. In 2022, there were just six, the lowest number ever recorded, Dr. Partridge said.
Piping plovers — small, dark-eyed shorebirds that nest in the sands of the Rockaways and along other shorelines near the city — face a similar plight. Their habitats are also shrinking, and their nests are threatened by washouts from storms. But even if the planet’s warming is limited to just 1.5 degrees Celsius above preindustrial levels — the target that scientists say could help avoid the most extreme effects of climate change — the piping plover would still lose more than 60 percent of its summer habitat along the Eastern Seaboard and in the Great Lakes and the Great Plains regions, according to Audubon Society calculations.
Earlier springs could bring other challenges for birds. Warblers, for example, have historically passed through New York City by the millions along long spring migratory routes from the Caribbean and South America to Canada. In a changing climate, their food supply along the way — insects — could peak in population before the migrating birds arrive, decreasing their energy stores on a long journey.
But at least one warbler may benefit from an earlier spring. A 2013 study found that black-throated blue warblers in New Hampshire were hatching two broods — double the usual rate during a single season — because they had begun breeding earlier in the year.
A landmark study published in 2019 found that three billion birds had disappeared from North America between 1970 and 2019, a drop of about 30 percent over a half-century. Although the study did not investigate the decline’s causes, habitat loss and degradation were cited as major factors, along with cats, collisions and pesticide use. In a Times Opinion piece, John W. Fitzpatrick and Peter P. Marra, heads of the Cornell Lab and Georgetown Environment Initiative, described the findings as “a staggering loss that suggests the very fabric of North America’s ecosystem is unraveling.”
Beyond climate change, birds in New York City are most immediately threatened by other human actions; between 90,000 and 230,000 migrating birds are killed in building collisions in New York City every year, the city Audubon Society says.
Safe places for birds have always been limited in the city. Large green spaces like Central Park, Forest Park and Prospect Park are crucial for foraging and shelter. But birds’ needs, which can require fallen leaves and branches to remain in place, are often at odds with the manicured parks preferred by many New Yorkers.
Still, bird-specific conservation has been the subject of city legislation in recent years. In 2019, the City Council passed Local Law 15, requiring new buildings to be made with collision-preventive materials. In 2021, the city approved a measure requiring that nonessential lights outside city-owned building be turned off overnight during important migratory periods.
The New York City Audubon Society is also pushing lawmakers to expand the ban on extraneous nighttime lighting to privately owned buildings, and it also has lent its support to the Dark Skies Act, a statewide “lights out” bill introduced last year, according to Tod Winston, a researcher with the organization.
To Mr. Winston, it is crucial to advocate for birds’ protection before it’s too late. He says the “canary in the coal mine” metaphor is apt when it comes to birds and climate change.
“All of our societies depend on these natural systems of insects, birds, plants in multiple ecosystems across the earth,” Mr. Winston said. The changes affecting birds should serve as a warning, he added, that “people are in trouble,” too.