Jonathan Lambert Science News Fri, 20 Sep 2019 08:43 UTC
Populations of rare and common birds alike are decreasing across North America, including (clockwise from top left) snowy owls, sanderlings, cactus wrens and Western meadowlarks.
Scientists found profound losses among both rare and common birds
Nearly 3 billion fewer birds exist in North America today than in 1970.
While scientists have known for decades that certain kinds of birds have struggled as humans (and bird-gobbling cats) encroach on their habitats, a new comprehensive tally shows the staggering extent of the loss. Nearly 1 in 3 birds — or 29 percent — has vanished in the last half century, researchers report September 19 in Science.
"Three billion is a punch in the gut," says Peter Marra, a conservation biologist at Georgetown University in Washington, D.C. The loss is widespread, he says, affecting rare and common birds alike. "Our study is a wake-up call. We're experiencing an ecological crisis."
"Three billion is a punch in the gut," says Peter Marra, a conservation biologist at Georgetown University in Washington, D.C. The loss is widespread, he says, affecting rare and common birds alike. "Our study is a wake-up call. We're experiencing an ecological crisis."
Looking at the loss of individual birds sets this study apart, says Hillary Young, an ecologist at the University of California, Santa Barbara who was not involved in the study. "So much of the focus in conservation is on the loss of species," but individual birds play an important role in ecosystems, pollinating plants, dispersing seeds and controlling pests.
"Often it's the common, abundant birds that keep these ecosystems ticking," Young says. Some biologists argue that, as rarer birds disappear, more common ones will swoop in and fill their niches. These common birds might be more adaptable, and able to persist as habitat shrinks, keeping the overall numbers of birds stable and basic ecosystem services intact.
But without a broad beakcount over many decades, "we just didn't know for sure," says Kenneth Rosenberg, an ornithologist at Cornell University.
So Rosenberg, Marra and their colleagues mined 12 databases built from decades of on-the-ground bird observations in the United States and Canada, often made by citizen scientists. Yearly observations built a record of population-level changes in 529 species, representing 76 percent of birds that breed in North America. A statistical analysis of these data let the team estimate population trends since 1970 and compare them with current best estimates of population size.
The numbers paint a grim picture: Most habitats and species have experienced tremendous losses, especially migratory birds. Grassland species fared the worst. Some 700 million individual birds across 31 species, including meadowlarks, have vanished since 1970, a 53 percent drop. American sparrows, little brown birds commonly seen flitting through backyards, saw the largest drop of any group of birds. Nearly a quarter — 750 million — have disappeared over the past five decades. Even invasive species like starlings, which are highly adaptive generalists, experienced massive losses, with their populations declining 63 percent.
Scientists estimate there are 3 billion fewer birds in North America today than in 1970. Both common and rare birds are disappearing across nearly all habitats.
"What's scary to me is that the common birds, even invasive ones, aren't faring any better than the rare birds," Young says. "These results clearly show they're just as vulnerable."
The researchers confirmed this trend with an unusual new way of monitoring birds — weather radar. Radar systems tracking the movement of clouds across the United States also register other large masses moving through the air, including flocks of migrating birds. After distinguishing these flocks from clouds, the researchers estimated the change in total biomass of birds migrating at night and found a 14 percent drop from 2007 to 2017.
While not directly comparable, the two methods reveal a similarly steep decline. "That [both methods] came to the same conclusion suggests these numbers aren't just being pulled out of a hat," says Morgan Tingley, an ornithologist at the University of Connecticut in Storrs. "They're real."
The study doesn't address why birds are disappearing, but many face habitat degradation and loss. "As habitats diminish, birds have nowhere to go," Rosenberg says. Cats may kill more than a billion birds a year (SN: 1/29/13), while nearly a billion more die in collisions with buildings (SN: 1/27/14), previous studies have found.
But the study offers some hope. Populations of waterfowl, like mallard ducks and Canada geese, have grown 56 percent since 1970. "This increase is no accident," Rosenberg says. "It's a direct result of decades of conservation efforts made by hunters and billions of dollars to protect these birds and their habitat." Rosenberg says he hopes this study will spurn similar concern for all birds.
"This paper doesn't tell us what the future holds," Tingley says. "Only what has happened up to this point. It's up to us to decide what to do next."
I've been a lifelong birder. In my youth, it was mu good fortune to know Mr. & Mrs. Allan & Helen Cruickshank. (My father was president of our local Audobon Society from around 1967 to 1976k, I love the critters.
I would go birdwatching with my father and usually see 'Dusky Seaside Sparrows,' which are now extinct.
I would translate sounds of bird calls for Mr. Cruikshank,. who'd lost his high pitched hearing range from an ack-ack blast near him when he was a side gunner on an Avro Lancaster? in WWII.
What a phenomenal couple! I just looked him up and remembered attending his funeral; (Obit: https://www.nytimes.com/1974/10/12/archives/allan-d-cruickshank-67-dies-noted-ornithologist-and-author-wrote.html) one of the earliest I ever went to.
Human rampant population increases and encroachment on the natural ecosystems coupled with the increase in pesticide use has taken its toll ...Glyphosate destroys ecosystems from soil to invertebrates on up the food chain . 60% of birds depend on insects for food ..
Jane Goodall: How Can We Believe It Is a Good Idea to Grow Our Food With Poisons? -
Darkmatter7 Americans are being poisoned everyday in a VARIETY of ways! TPTB call it a Slow Kill. All, are State Sanctioned Crimes Against Humanity which are Publicly Funded yet ALL Profits are Private!? What a Racket. And many People Who Think, think that it's outrageous and annoying that I call these Parasitic Predators that which they are..... Whores 4 War R US!?!?!?!
black,kristi Yes, it is a Long list and insane psychopathic war whores are exactly what they are . They will destroy themselves with the whole planet for their greed , but Nature has the last word and striking back .
Reader Comments
Checkout these terms:
> Solar radiation management
> Stratospheric aerosol injection
Good information at the following sites:
www.climateviewer.com
www.geoengineeringwatch.org
I would go birdwatching with my father and usually see 'Dusky Seaside Sparrows,' which are now extinct.
I would translate sounds of bird calls for Mr. Cruikshank,. who'd lost his high pitched hearing range from an ack-ack blast near him when he was a side gunner on an Avro Lancaster? in WWII.
What a phenomenal couple! I just looked him up and remembered attending his funeral; (Obit: https://www.nytimes.com/1974/10/12/archives/allan-d-cruickshank-67-dies-noted-ornithologist-and-author-wrote.html) one of the earliest I ever went to.
R.C.
Jane Goodall: How Can We Believe It Is a Good Idea to Grow Our Food With Poisons? -
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