North America Has Lost 3 Billion Birds, Scientists Say
OVER THE PAST half-century, North America has lost more than a quarter of its entire bird population, or around 3 billion birds.
That’s according to a new estimate published in the journal Science by researchers who brought together a variety of information that has been collected on 529 bird species since 1970.
“We saw this tremendous net loss across the entire bird community,” says Ken Rosenberg, an applied conservation scientist at the Cornell Lab of Ornithology in Ithaca, N.Y. “By our estimates, it’s a 30% loss in the total number of breeding birds.”
Rosenberg and his colleagues already knew that a number of bird populations had been decreasing.
“But we also knew that other bird populations were increasing,” he says. “And what we didn’t know is whether there was a net change.” Scientists thought there might simply be a shift in the total bird population toward more generalist birds adapted to living around humans.
To find out, the researchers collected data from long-running surveys conducted with the help of volunteer bird spotters, such as the North American Breeding Bird Survey and the Audubon Christmas Bird Count. They combined that data with a decade’s worth of data on migrating bird flocks detected by 143 weather radar installations.
Their results show that more than 90% of the loss can be attributed to just a dozen bird families, including sparrows, warblers, blackbirds and finches.
Common birds with decreasing populations include meadowlarks, dark-eyed juncos, horned larks and red-winged blackbirds, says Rosenberg. Grassland birds have suffered a 53% decrease in their numbers, and more than a third of the shorebird population has been lost.
Bird populations that have increased include raptors, like the bald eagle, and waterfowl.
“The numbers of ducks and geese are larger than they’ve ever been, and that’s not an accident,” says Rosenberg. “It’s because hunters who primarily want to see healthy waterfowl populations for recreational hunting have raised their voices.”
Applied ecologist Ted Simons of North Carolina State University says that trying to enumerate bird populations and tracking them over time is a daunting task with a lot of uncertainty.
“People are doing a wonderful effort to try and understand our bird populations, but the actual systems that we have in place to try and answer really tough questions like this are really far short of what we need,” says Simons. “We’re certainly far from having the tools and having the resources to have real high confidence in our estimates of these populations.”
Still, he says, “I think it is very likely that we are seeing substantial declines in our bird populations, particularly migratory birds.”
Other researchers say this continent-wide decrease in bird numbers is about what they expected.
“I think that I buy the magnitude of loss,” says Kristen Ruegg, a biologist at Colorado State University in Fort Collins. “Overall, the conclusions weren’t necessarily surprising. I mean, they were depressing but not surprising,”
Ruegg says there have been hints that the loss was this large from a variety of sources over the past few decades. But in most cases, these were species-specific accounts of local extinctions or models of projected losses resulting from things like climate change.
This study, she says, “really sort of wakes people up to the idea that this is happening.”
Elise Zipkin, a quantitative ecologist at Michigan State University, says the loss of individuals can be a big problem.
“Just because a species hasn’t gone extinct or isn’t even necessarily close to extinction, it might still be in trouble,” she says. “We need to be thinking about conservation efforts for that.”
The researchers cite a variety of potential causes for the loss of birds, including habitat degradation, urbanization and the use of toxic pesticides, notes Zipkin.
“And so I think this kind of lays the gauntlet,” she says, “for people to be thinking about ‘All right, how can we estimate maybe the relative contributions of these things to individual populations and their declines.'”
The Lesson of the Birds
by Kevin Alfred Strom
ONE OF MY SMALL pleasures in life is bird watching, which gives me a great deal of peace in this world of constant conflict. Over the years, I have discovered that there is much to be learned from our avian neighbors, lessons that illustrate the laws of Nature that apply to us as much as to them.
Recently, a listener sent me this article from the Richmond, Virginia Times-Dispatch entitled, “Songbirds in the Midwest are singing cowbird blues — Raising orphaned chicks wipes out foster families”:
The Midwest has become a disaster area for migrant songbirds and a paradise for a feathered freeloader who tricks other birds into raising its young.
Songbirds that fly thousands of miles from South America to nest in the forests of the Midwest are being pushed toward population collapse by cowbirds that lay eggs in other birds’ nests and force the hosts to feed and nurture cowbird chicks.
A study to be published today in the journal Science shows that migrant songbird populations are in steep decline in the Midwest, and naturalist, Scott K. Robinson, of the Illinois Natural History Survey, says that parasitic cowbirds are the principal cause. Robinson said a single cowbird female lays eggs in a dozen songbird nests and then leaves them in the songbirds’ care. “The cowbirds hatch earlier, grow faster and then crowd out the host young,” said Robinson. “The songbird young just starve to death.”
Robinson said the cowbirds are thriving in the Midwest because the big woods have been felled for farm fields and pastures, depriving the migrant songbirds of the protection of the deep forests. The songbirds include tanagers, warblers, thrushes, flycatchers, and grosbeaks.
A survey by more than 125 researchers and assistants of 5,000 nesting sites in five states found that up to 50 per cent of the songbirds were not successful in raising young. This is not enough to maintain the songbird population at those sites, said Robinson. The survey was done in Indiana, Michigan, Wisconsin, Illinois, and Missouri.
“These birds don’t have an evolutionary history of dealing with cowbirds,” said Robinson. “They haven’t learned to recognize that a cowbird egg is not their egg and that cowbird young are not their young.”
Most migrant songbirds, he said, “imprint on the young and take care of whatever is in the nest,” even if it is a cowbird chick. Some resident birds, however, won’t tolerate the freeloading cowbirds.
“The Baltimore Oriole will puncture a cowbird egg and throw it out,” he said. Robins also reject the cowbird egg. Both robins and orioles are thriving.
Robinson said that the study shows that the problem could be corrected by establishing a network of forests no smaller than 20,000 acres. This is the minimum size, he said, to give the migrant songbirds a haven from the cowbirds.
I’m amazed that the controlled media allowed that article to leave their presses in that form, but there it is. There are so many lessons to be learned there.
Here we have beautiful, brightly colored, noble-looking creatures with sweet poetry and music their art; threatened by ugly brown parasite birds, whose only distinction is that they can sometimes fool the beautiful ones into thinking that there is no difference between them.
Here we have parasite young crowding out the legitimate young in the nest. Have you seen a big-city classroom recently? Here we have parents spending their precious time and energy feeding and caring for the parasite young. Its parallel is the vast wealth and even lives which are squandered to “uplift” the forever miserable here or overseas. Its parallel is the Christian Children’s Fund and interracial adoptions fostered by our governments and our churches. We are digging our graves with a stupid — extremely stupid — smile on our foolish White faces.
The songbirds are dying as we will die. Some populations have fallen as much as 93% and experts are predicting multiple extinctions across this continent. As the warbler’s trill is replaced by the raucous cowbird squawk, so Vivaldi is eclipsed by killer rap.
What is the solution for the songbirds? What are the only hopes for their survival? One was mentioned in the Times-Dispatch article I quoted. It is the establishment of a habitat for the songbirds, to give the songbirds a “haven from the cowbirds.” The songbirds need — as we also need — and as every species needs to survive, a defendable territory of its own, where its parasites and other enemies are not present, where it can raise its own young, and its own precious and uniquely wonderful and beautiful genetic heritage will be passed on, unmixed, to the next generation. Without our own territory we perish. A nation that declares itself a melting-pot of all races will soon cease to be anything but a graveyard for its people.
Now songbirds could survive the clearing of the forests, if that was all there was to it. They nest reasonably well in meadows and near farmer’s fields. Change of habitat by itself isn’t fatal. It is that due to the clearing of their traditional forest habitat, they are now forced to share all their territory with cowbirds. In other words, they are being forcibly integrated with cowbirds. It is the integration with cowbirds that is fatal. Give songbirds their own territory, by whatever means, and they will thrive again.
A Discover magazine article last year mentioned another, more controversial solution advocated by some conservationists. In areas where the last remaining songbirds are now threatened, they are capturing and killing the invading cowbirds with poison gas. The results? I quote:
Some [songbird] species are in trouble …they’re raising too many baby cowbirds and not enough young of their own. Among the songbirds that have been pushed closer to extinction by cowbirds are the Least Bell’s Vireo of California, the Black-Capped Vireo of Texas, and the Kirtland’s Warbler of Michigan. The situation has forced conservationists into the uncomfortable position of advocating cowbird extermination programs.
“While we don’t like killing cowbirds,” says Jane Griffith, a biological consultant, “we do like to hear the songs of endangered species.” On a local level, at least, such programs seem to help. An example is the one that Griffith and her husband, John Griffith, have worked on at Camp Pendleton, a Marine base in Oceanside, California, that is one of the last refuges of the Least Bell’s Vireo. In the early 1980s, half the vireo nests there were parasitized. By 1994, after some 4,800 cowbirds had been trapped and gassed with carbon monoxide, parasitism had declined to 1 percent. More important, the number of male vireos had increased more than fifteenfold, from 27 in 1981 to 420 in 1993. Similar success has been reported by cowbird control program at Fort Hood, Texas, which has become a retreat for the Black-Capped Vireo.
Some bird species, especially orioles and robins, are thriving despite efforts by the cowbirds to parasitize them. They are thriving because they do not welcome the cowbirds to their nests. They are thriving because they defend their territory from invaders. They are thriving because they will puncture the cowbird’s egg and eject it from the nest. The Condor magazine, for August 1995, mentioned another species, Couch’s Kingbird, that has successfully resisted parasitism. What is the successful survival technique of Couch’s Kingbird? — Egg discrimination. What natural survival technique has been made into a crime and into a dirty word by our enemies? The ability to discriminate — which simply means to choose — sometimes makes the difference between life and death.
There are other amazing parallels between the cowbirds’ parasitism and our dispossession. Since they don’t have the burden of raising her own young, cowbirds reproduce at a much faster rate than other bird species. A single female cowbird can lay as many as 50 eggs in a single breeding season. Since welfare recipients are freed of much of the burden of raising their broods, they also …well, you get the picture. And you also know who carries the burden.
And as we are threatened by multiform parasites, both those already here and those flowing across our southern border, so are the songbirds. Read this excerpt from the Discover magazine article:
Meanwhile, a new threat to songbirds has surfaced — an invasion of another species of cowbird. Since 1985 the Shiny Cowbird of South America has been sighted in Florida. According to Alexander Cruz, a biologist at the University of Colorado in Boulder, it hasn’t yet been caught parasitizing nests, but that’s just a matter of time.
Ladies and gentlemen, I have am doing my best to bring you a lesson from Nature. For if we as a people continue to violate Nature’s laws, we shall surely perish.
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Source: American Dissident Voices broadcast, February 24, 1996 and National Public Radio