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There are nearly three billion fewer birds in the United States and Canada now that there were 50 years ago - a loss that equals more than one in every four birds. Pictured, an evening grosbeak, a member of the finch family, found in North America

There are nearly three billion fewer birds in the United States and Canada now that there were 50 years ago – a loss that equals more than one in every four birds.

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Experts studying historical bird observations, along with a decade of radar data on migratory birds, report evidence of a & # 39; widespread ecological crisis & # 39 ;.

They discovered that North American bird populations have fallen by 29 percent since 1970.

Analysis brought & # 39; huge losses & # 39; exposed to different groups of birds and habitats – from iconic songbirds such as the pasture, to long-distance migrants such as swallows and even common garden birds such as sparrows.

Although the study did not look at the causes of the decline of each species, the team suggests that habitat loss due to agriculture and urbanization is probably an important cause.

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There are nearly three billion fewer birds in the United States and Canada now that there were 50 years ago - a loss that equals more than one in every four birds. Pictured, an evening grosbeak, a member of the finch family, found in North America

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There are nearly three billion fewer birds in the United States and Canada now that there were 50 years ago – a loss that equals more than one in every four birds. Pictured, an evening grosbeak, a member of the finch family, found in North America

WHAT CAUSES THE BIRD Drops?

The study was not intended to analyze the causes of the individual decline of each bird species.

Nevertheless, the researchers noted that the sharp drop in North American birds is in parallel with the loss of birds elsewhere in the world.

This suggests that there are several interacting causes that reduce breeding success and increase the death rate.

The biggest factor driving the decline, the team said, is probably the widespread loss and decline of habitats, mainly due to growing agriculture and urbanization.

Previous studies have documented various causes for bird victims.

These include predation by free-roaming house cats, collisions with man-made structures and the pervasive use of pesticides that are thought to cause widespread deterioration in insects, which serve as an essential food source for birds.

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Climate change is expected to aggravate the challenges for bird species by further changing the habitats and threatening the plant communities that birds rely on.

The researchers have called for more research to better identify the main causes of the decline of individual species.

& # 39; Multiple independent lines of evidence show a huge reduction in the number of birds, & # 39; said lead researcher and ornithologist Ken Rosenberg of Cornell University.

& # 39; We expected continuous deterioration of endangered species. But for the first time, the results also showed profound losses in common birds in all habitats, including backyard birds. & # 39;

Because birds are indicators of environmental health, the findings indicate that natural systems in the US and Canada are now so heavily affected by human activities that they can no longer support the same robust wildlife.

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Of the nearly three billion lost birds, 90 percent belonged to 12 bird families, including finches, sparrows, swallows and singers.

These were common, widespread species that played influential roles in food webs and ecosystems, such as spreading seeds and controlling pests.

Meadow birds have been hit particularly hard, with a 53 percent reduction in their numbers – the equivalent of more than 720 million birds – since 1970.

Meanwhile, shorebirds, most of whom live in sensitive coastal habitats, were already at & # 39; dangerously low & # 39; levels before they lost more than a third of their population.

Researchers also discovered that the volume of spring migration, measured in the night sky with radar, has fallen by 14 percent in the last decade.

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& # 39; This data is consistent with what we see elsewhere with other taxa, showing huge decline, including insects and amphibians, & # 39; said paper author and biologist Peter Marra of Georgetown University in Washington DC.

& # 39; It is necessary to address immediate and ongoing threats, as the domino effects can lead to the decay of ecosystems that people depend on for our own health and livelihoods. & # 39;

In addition, he noted: & # 39; people around the world cherish birds on their own. Can you imagine a world without birdsong? "

The evidence for the deterioration came from both 50-year ground observation of birds, along with the detection of migrating birds in the sky over a 10-year period by 143 different weather radar stations in North America.

& # 39; Citizen science participants have contributed critical scientific data to demonstrate the international scale of bird losses & # 39 ;, said paper author and natural biologist John Sauer of the US Geological Survey.

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& # 39; Our results also provide insights into actions we can take to undo the declines. & # 39;

Experts studying historical bird observations, along with a decade of radar data on migratory birds, report evidence of a & # 39; widespread ecological crisis & # 39 ;. They discovered that North American bird populations have fallen by 29 percent since 1970

Experts studying historical bird observations, along with a decade of radar data on migratory birds, report evidence of a & # 39; widespread ecological crisis & # 39 ;. They discovered that North American bird populations have fallen by 29 percent since 1970

Experts studying historical bird observations, along with a decade of radar data on migratory birds, report evidence of a & # 39; widespread ecological crisis & # 39 ;. They discovered that North American bird populations have fallen by 29 percent since 1970

The study was not intended to analyze the causes of the individual decline of each species.

Nevertheless, the researchers noted that the sharp drop in North American birds is in parallel with the loss of birds elsewhere in the world.

This suggests that there are several interacting causes that reduce breeding success and increase the death rate.

The biggest factor driving the decline, the team said, is probably the widespread loss and decline of habitats, mainly due to growing agriculture and urbanization.

Previous studies have documented various causes for bird victims.

These include predation by free-roaming house cats, collisions with man-made structures and the pervasive use of pesticides that are thought to cause widespread deterioration in insects, which serve as an essential food source for birds.

Climate change is expected to aggravate the challenges for bird species by further changing the habitats and threatening the plant communities that birds rely on.

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The researchers have called for more research to better identify the main causes of the decline of individual species.

Analysis revealed & # 39; huge losses & # 39; with different groups of birds and habitats - from iconic songbirds such as the pasture, to migrants over long distances such as swallows and even common garden birds such as sparrows

Analysis revealed & # 39; huge losses & # 39; with different groups of birds and habitats - from iconic songbirds such as the pasture, to migrants over long distances such as swallows and even common garden birds such as sparrows

Analysis revealed & # 39; huge losses & # 39; with different groups of birds and habitats – from iconic songbirds such as the pasture, to migrants over long distances such as swallows and even common garden birds such as sparrows

& # 39; The story is not over yet. There are so many ways to save birds. Some require policy decisions, & said paper author and president of the American Bird Conservancy Michael Parr.

& # 39; We can also work on banning harmful pesticides and effectively financing effective bird protection programs & # 39; s. & # 39;

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& # 39; Each of us can make a difference with everyday actions that together can save the lives of millions of birds – actions such as making windows safer for birds, keeping cats indoors and protecting habitats. & # 39;

Although the study did not look at the causes of the decline of each species, the team suggests that habitat loss due to agriculture and urbanization is probably an important cause. Pictured, a Baltimore oriole, a migratory bird that can be found in the eastern parts of North America

Although the study did not look at the causes of the decline of each species, the team suggests that habitat loss due to agriculture and urbanization is probably an important cause. Pictured, a Baltimore oriole, a migratory bird that can be found in the eastern parts of North America

Although the study did not look at the causes of the decline of each species, the team suggests that habitat loss due to agriculture and urbanization is probably an important cause. Pictured, a Baltimore oriole, a migratory bird that can be found in the eastern parts of North America

However, the study has documented a number of promising rebounds that have been partly triggered by human conservation efforts.

Waterbirds – such as ducks, geese and swans – have had a & # 39; remarkable & # 39; recovery found, the researchers found.

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According to them, this was made possible through investments in nature conservation by hunters and billions of dollars in government funding for the protection and restoration of wetlands.

In the meantime, birds of prey such as the bald eagle also have & # 39; spectacular & # 39; made comebacks since the & # 39; 70.

Experts attribute these recoveries to the banning of the harmful pesticide DDT and the protection provided by the legislation for endangered species in the US and Canada.

Because birds are indicators of environmental health, the findings indicate that natural systems in the US and Canada are now so heavily affected by human activities that they can no longer support the same robust wildlife. Pictured, a snow owl

Because birds are indicators of environmental health, the findings indicate that natural systems in the US and Canada are now so heavily affected by human activities that they can no longer support the same robust wildlife. Pictured, a snow owl

Because birds are indicators of environmental health, the findings indicate that natural systems in the US and Canada are now so heavily affected by human activities that they can no longer support the same robust wildlife. Pictured, a snow owl

& # 39; It is a wake-up call that we have lost more than a quarter of our birds in the US and Canada. But the crisis extends far beyond our individual limits & # 39 ;, said paper author and ecologist Adam Smith of Environment and Climate Change Canada.

& # 39; Many of the birds that breed in Canadian backyards spend the winter in the US and move further south – from Mexico and the Caribbean to Central and South America. & # 39;

& # 39; What our birds need now is a historic, hemispherical effort that unites people and organizations with one common goal: to bring back our birds. & # 39;

The full findings of the study were published in the journal Science.

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