A new paper signals an ecological crisis, and humans are to blame. There are far fewer birds today than in the 1970s, thanks largely to habitat destruction.
Image: picture-alliance/blickwinkel/McPHOTO
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Bird populations have dropped 29% since the 1970s in the US and Canada, scientists reported on Thursday.
Researchers blamed habitat loss and degradation, the chemical eradication of insects, and cats.
"Birds are in crisis," said Peter Marra, director of the Georgetown Environment Initiative at Georgetown University and co-author of the study.
"The take-home message is that our findings add to mounting evidence with other recent studies showing massive declines in insects, amphibians and other taxa, signaling a widespread ecological crisis," Marra added. "Birds are the quintessential indicators of environmental health, the canaries in the coal mine, and they're telling us it's urgent to take action to ensure our planet can continue to sustain wildlife and people."
The paper, published in the journal Science, detailed how researchers tracked populations of 529 species using historical bird counts, and also weather radar data that showed declines in the volume of migrating birds.
Human activity threatens thousands of species with extinction: Red List
The International Union for the Conservation of Nature's annual Red List assesses 97,000 species — 27,000 face extinction. Poaching, invasive pests, agriculture and climate change are driving many of them to the brink.
Image: picture-alliance/dpa/WWF
Hope for mountain gorillas
Let's start with the good news. According to the latest Red List update, the number of mountain gorillas has significantly increased. The IUCN has said the number of animals has risen from about 680 a decade ago to more than 1,000 now. Intensive conservation action such as removal of snares has contributed to the rebound of the mountain gorilla, which inhabits the Congo region's jungles.
Image: Reisedoktor/Wikipedia
Whales get a reprieve
Fin whales are now considered vulnerable rather than the more worrisome label of endangered. Their number has roughly doubled since the 1970s, to around 100,000 individuals, according to the IUCN. The situation of gray whales has also been upgraded — from critically endangered to endangered. Bans on commercial whaling have made a real impact on conservation.
Image: picture-alliance/ZUMAPRESS/VW Pics
Dampened euphoria
Yet the IUCN also issued warnings about the consequences of overfishing. For example, 13 percent of grouper species worldwide and 9 percent of the approximately 450 fish species in Lake Malawi in eastern Africa are threatened with extinction. "Depleting fish stocks are a serious concern for food security, particularly for coastal communities in developing countries," the IUCN said.
In a previous Red List update, the Mauritian flying fox — an important pollinator — moved from vulnerable to endangered. The bat population fell by a whopping 50 percent from 2015 to 2016 due largely to government-implemented culling sparked by alleged damage to fruit crops. The megabat species also faces threats from deforestation, illegal hunting and an increase in cyclone activity.
Image: M. D. Parr
Invasive species threaten Australian wildlife
Invasive species are threatening a number of unique Australian reptiles. This grassland earless dragon has shifted from vulnerable to endangered. It often falls prey to feral cats, as well as changes to the intensity and frequency of bushfires. Like most native Australian wildlife, the reptile is adapted to environmental conditions that existed before European settlement.
Image: Will Osborne
A precious species
Taking its name from "The Lord of the Rings" character Smeagol — aka Gollum — the precious stream toad is also on the list of species threatened with extinction. It is listed as vulnerable, largely as a result of expanding tourist resorts and complexes in its Genting Highlands habitat in Malaysia.
Image: Chan Kin Onn
Junk food parrots
The population of keas, New Zealand's Bird of the Year 2017, is declining rapidly, mostly due to tourists who keep feeding the curious parrots junk food. As a result, the birds get used to trying novel food and end up eating poison bait meant to control pests such as rats, stoats, or possums, which destroy up to 60 percent of the birds' nests each year. You can see the connection, can't you?
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No sand eel, no kittiwake
Black-legged kittiwakes rely on certain key prey, like sand eels. But a lack of eels to eat means breeding colonies in the North Atlantic and Pacific are struggling to feed their chicks. Globally, the species is thought to have declined by around 40 percent since the 1970s. The main cause is overfishing and alterations in the ocean due to climate change.
The snowy owl is vulnerable, with recent population estimates much lower than previously thought. Climate change has hit the iconic Arctic bird hard, as it has increased snowmelt and reduced the availability of rodent prey. A quarter of bird species reassessed in the Red List, including the snowy owl, have become more endangered.
Image: Imago/CTK Photo
Reebok namesake in danger
Five species of African antelopes — of which four were previously assessed as least concern — have been declining drastically as a result of poaching, habitat degradation and competition with domestic livestock. One of these is the gray rhebok, for which the Reebok sports brand is named.
Image: UltimateUngulate/Brent Huffman
World's largest antelope in trouble
The world's largest antelope, the giant eland — previously assessed as least concern — is also vulnerable. Its estimated global population is between 12,000 and 14,000 at most, with fewer than 10,000 mature animals. This species is declining due to poaching for bushmeat, human encroachment into protected areas and expansion of agriculture and livestock grazing.
Image: UltimateUngulate/Brent Huffman
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'Landmark paper'
Ornithological experts were quick to react to the alarming study results. "This is a landmark paper. It's put numbers to everyone's fears about what's going on," said Joel Cracraft, curator-in-charge of the Department of Ornithology at the American Museum of Natural History, who wasn't part of the study. "It's even more stark than what many of us might have guessed," Cracraft said.
More than 90% of the drop came from 12 mostly common species including sparrows, warblers, blackbirds, and finches.
The worst hit category of birds were grassland birds, dropping 53% due to agricultural intensification. Shorebirds, often migratory, dropped 37%, due to habitat degradation and the destruction of migratory destinations.
Migratory birds in general suffered a steep decline, particularly in bird species that migrate to the tropics.
The study matches similar results from other parts of the world, including Europe.