What 2.9 Billion Birds Can Tell Us About Climate Change | Environment | Hudson Valley | Chronogram Magazine

The United Nations’ Climate Action Summit commenced this week in New York City, bringing together leaders in government, business, and civil society from across the world. They were there to discuss solutions for the climate crisis and boost ambition to meet an ever-worsening problem. (President Trump spent only 14 minutes at the summit, after which he mocked 16-year-old Swedish activist Greta Thunberg from the friendlier confines of Twitter.)

Let’s start with the good news. In advance of the summit, the UN Development Programme (UNDP) and the UN Framework Convention on Climate Change (UNFCCC) jointly issued a report reviewing the momentum since the 2015 Paris Agreement. The report’s authors found “many reasons for optimism,” including that more and more key actors, from nations to corporations, are aligning their policies and plans with the tenets laid out in the Agreement.

But—there’s always a “but” when the topic is the climate crisis—while climate action has accelerated since Paris, “it still falls far short of an unprecedented transformation needed to limit impacts of climate change,” the report found. The consequences are already here, in the forms of increased coastal flooding, more intense storms, more damaging wildfires, lower air quality, and more extreme heat. Even if we’re able to limit warming to the goal set by the Paris Agreement of 1.5 °C above pre-industrial levels (we’re not on track), many of these effects are likely to be irreversible.

Canaries in the Coal Mine

Scientists are beginning to quantify the ecological impact warming has already had, and the picture isn’t pretty. A study published last week in the journal Science put a stark number on the damage humans have already wrought on one segment of the environment: birds. The study, gloomily titled “Decline of North American avifauna,” estimated that the net loss of wild birds in the continental United States and Canada has been 2.9 billion since 1970, a 29-percent decline in population.

It is, frankly, a staggering number. As Gustave Axelson writes for the Cornell Lab of Ornithology, which led the research:

The scale of loss portrayed in the Science study is unlike anything recorded in modern natural history. While the Passenger Pigeon likewise suffered cascading losses more than a century ago, that was a population loss among one species, mostly in eastern North America. This research portrays massive losses among hundreds of species of birds from coast to coast.

Declines were found in every North American biome, from Arctic tundra to western arid lands, except for the wetlands, the only bioregion to see a net gain. Forests have lost more than one billion birds. Grassland bird populations have declined by 53 percent, more than 720 million birds in fewer than 50 years. The driving factor in these declines is likely habitat loss, particularly agricultural intensification and development.

“I think this analysis shows that we’re eating away at the foundations of all of our major ecosystems on the continent,” said Arvind Panjabi, study coauthor and avian conservation scientist at the Colorado-based Bird Conservancy of the Rockies. “These numbers show that the world has changed a lot since 1970.”

Scientists have long known that some bird species are vulnerable to extinction, but the Science study analyzed more than 500 species—about 76 percent of the total breeding species in the US and Canada—to get a fuller picture. In focusing too much on extinction, the authors note, we often ignore the “loss of abundance within still-common species and in aggregate across large species assemblages.”

Common bird species are important to a well-functioning ecosystem: they control pests, help pollinate flowers, and disperse seeds. Bird populations, then, are excellent indicators of environmental health and ecosystem integrity; furthermore, it’s much easier for scientists to monitor many bird species over vast periods of time and distance scales than any other animal group.

The findings showed that of the 2.9 billion birds lost, nearly 90 percent belong to just 12 families, including common species like sparrows, blackbirds, finches, and warblers. We may not notice loss among those populations because of the shifting baseline phenomenon. As Hillary Young, a conservation biologist at the University of California, Santa Barbara, told the New York Times: “Declines in your common sparrow or other little brown bird may not receive the same attention as historic losses of bald eagles or sandhill cranes, but they are going to have much more of an impact.”

For example, take the wood thrush, a bird that is still common in the forests of the Eastern US, including here in the Hudson Valley. It isn’t classified as threatened for conservation purposes, but nearly six in 10 have been lost since 1970, part of an overall 17-percent decline in Eastern forest birds over that span.

It’s Not All Bad

There is some good news. Some bird populations are doing well, as a result of direct human intervention. Waterfowl such as ducks, geese, and swans have made remarkable recoveries due to conservation by hunters and government funding for wetland protection and restoration. Bald eagles have rebounded since DDT was banned in the 1970s. Turkeys are also on the rise.

The stories of these birds indicate what’s possible when we make and stick to conservation commitments. The real work needs to be done at the level of governments and international corporations, but there are seven simple actions you can take to make your home and life more bird-friendly:

  • Make windows safer by installing screens or breaking up reflections. More than one billion birds die annually by flying into windows.
  • Keep cats indoors. This is particularly important locally, now that New York has banned cat declawing. Cats kill an estimated 2.4 billion birds per year in the US—the number one cause of death after habitat loss.
  • Use native plants and reduce your lawn.
  • Avoid pesticides.
  • Drink shade-grown coffee. Growing coffee in the sun often necessitates habitat destruction and the use of pesticides. Look for the “bird-friendly” certification from the Smithsonian Migratory Bird Center when buying coffee.
  • Reduce plastic use.
  • Do citizen science. Monitoring birds is the first step to protecting them, and paying attention and reporting what’s happening locally will help scientists know where and when birds are declining.

As the study’s lead scientist, Cornell Lab of Ornithology conservation scientist Ken Rosenberg, notes, even if 30 percent of North America’s birds are lost, there remains 70 percent to save. Will that spur implementation of more conservation measures? Studies like these can be a wake-up call, but action must come soon.

“I don’t think any of these really major declines are hopeless at this point,” Rosenberg said. “But that may not be true 10 years from now.”

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