By Jerri-Lynn Scofield, who has worked as a securities lawyer and a derivatives trader. She is currently writing a book about textile artisans.
Science magazine Thursday released a study, Decline of the North American avifauna, documenting a nearly 30% drop in North American bird populations since 1970.
That translates to a loss of nearly three billion birds.
The study has been widely reported, and even ornithologists have been shocked by the extent of the decline. The New York Times reports in Birds Are Vanishing From North America:
“We were stunned by the result — it’s just staggering,” said Kenneth V. Rosenberg, a conservation scientist at Cornell University and the American Bird Conservancy, and the lead author of the new study.
“It’s not just these highly threatened birds that we’re afraid are going to go on the endangered species list,” he said. “It’s across the board.”
An account in the Cornell Chronicle, Nearly 30% of birds in U.S., Canada have vanished since 1970, connects the dots:
Rosenberg said the results of this study point to something bigger than birds.
“It’s a strong signal that our human-altered landscapes are losing their ability to support birdlife,” he said. “And that is an indicator of a coming collapse of the overall environment.”
Science also published a precis, Three billion North American birds have vanished since 1970, surveys show, which notes:
“I frankly thought it was going to be kind of a wash,” Rosenberg says. He expected rarer species would be disappearing but common species would be on the rise, compensating for the losses, because they tend to be generalists, and more resilient. Indeed, waterfowl and raptors are thriving, thanks to habitat restoration and other conservation efforts. But the declines in many other species, particularly those living along shorelines and in grasslands, far exceeded those gains, Rosenberg and his colleagues report. Grassland birds have declined by 53% since 1970—a loss of 700 million adults in the 31 species studied, including meadowlarks and northern bobwhites. Shorebirds such as sanderlings and plovers are down by about one-third, the team says. Habitat loss may be to blame.
The familiar birds that flock by the thousands in suburbs were not exempt. “There’s an erosion of the numbers of common birds,” Rosenberg says.
From the text of the full paper:
More than 90% of the total cumulative loss can be attributed to 12 bird families (Fig. 3A), including sparrows, warblers, blackbirds, and finches. Of 67 bird families surveyed, 38 showed a net loss in total abundance, whereas 29 showed gains (Fig. 3B), indicating recent changes in avifaunal com- position (table S2). While not optimized for species-level analysis, our model indicates 19 widespread and abundant landbirds (including 2 introduced species) each experienced population reductions of >50 million birds (data S1). Abundant species also contribute strongly to the migratory passage detected by radar , and radar-derived trends provide a fully independent estimate of widespread declines of migratory birds.
Our study documents a long-developing but overlooked biodiversity crisis in North America—the cumulative loss of nearly 3 billion birds across the avifauna. Population loss is not restricted to rare and threatened species, but includes many widespread and common species that may be disproportionately influential components of food webs and ecosys- tem function. Furthermore, losses among habitat generalists and even introduced species indicate that declining species are not replaced by species that fare well in human-altered landscapes. Increases among waterfowl and a few other groups (e.g., raptors recovering after the banning of DDT) are insufficient to offset large losses among abundant species (Fig. 3). Importantly, our population loss estimates are conservative since we estimated loss only in breeding populations. The total loss and impact on communities and ecosystems could be even higher outside the breeding season if we consider the amplifying effect of “missing” reproductive output from these lost breeders. [citations omitted]
Over to the Cornell Chronicle:
“We want to keep common birds common, and we’re not even doing that,” said Peter Marra, a study co-author who contributed to the analysis in his former position as director of the Smithsonian Migratory Bird Center. Marra is now director of the Georgetown Environment Initiative.
“Put that into the context of the other declines that we’re seeing, from insects to amphibians, and it suggests that there’s an ecosystem collapse that should be troubling to everybody,” Marra said. “It’s telling us that our environment is not healthy. Not for birds, and probably also not for humans.”
Having enjoyed some remarkable birding in Canada – including visiting Churchill, Manitoba, during the golden plover’s breeding season, watching (from a boat) oodles of puffins — aka a “circus” or “puffinry” – nesting in Newfoundland, and participating in Christmas bird counts in Whistler, British Columbia, I want to highlight that the study’s finding that the decline extends beyond US borders to Canada as well. According to CBC News, N.S. bird watchers shocked by ‘staggering’ bird declines:
“This is not just North America,” [Lucas Berrigan, who works for Bird Studies Canada,] said. “There is a global crisis and I think we need to… take this more seriously than we have previously.”
“Barn swallows, chimney swifts and nighthawks, as well as seabirds, storm petrels in particular, these are birds that are usually out of sight of most people, but they are of a significant importance ecologically,” Berrigan said.
“We’ve seen quite large declines in those populations. The largest population of one of these seabirds has declined nearly 50 per cent in the past 35 years.”
Others impacted include backyard birds, warblers, finches, sparrows and songbirds, as well as long distance birds like swallows and sandpipers that come to Canada from the Arctic.
Berrigan noted that another recently published paper spoke about how neonicotinoid — a pesticide — is affecting bird migration.
“In short, they lose a significant amount of body fat when feeding on seeds treated with very small amounts of [neonicotinoids],” he said.
“Body fat is extremely important for migratory birds since it determines how far they can fly at a given time.”
Causes of Bird Population Decline
The principal causes of the decline are well-known: habitat loss, and pesticide use, which intentionally decimates insect populations.
The Grey Lady reports:
Grassland species have suffered the biggest declines by far, having lost 717 million birds. These birds have probably been decimated by modern agriculture and development.
“Every field that’s plowed under, and every wetland area that’s drained, you lose the birds in that area,” Dr. Rosenberg said.
Rachel Carson’s classic, Silent Spring, originally serialised in The New Yorker in 1962, attracted notice from President John F Kennedy, and ultimately, helped catalyse a ban on DDT. The chemical had destroyed populations of raptors, including the iconic American bald eagle. The latest study is yet one more example showing that the lessons Carson conveyed, alas, have been forgotten.
What Is To Be Done?
Absent immediate and targeted conservation activity, bird populations will continue to decline. The paper pointed out that extinction of even common species – such as the passenger pigeon – can occur rapidly:
Extinction of the Passenger Pigeon (Ectopistes migratorius), once likely the most numerous bird on the planet, provides a poignant reminder that even abundant species can go extinct rapidly. Systematic monitoring and attention paid to population declines could have alerted society to its pending extinction. Today, monitoring data suggest that avian declines will likely continue without targeted conservation action, triggering additional endangered species listings at tremendous financial and social cost. Moreover, because birds provide numerous benefits to ecosystems (e.g., seed dispersal, pollination, pest control) and economies (47 million people spend 9.3 billion U.S. dollars per year through bird-related activities in the U.S.), their population reductions and possible extinctions will have severe direct and indirect consequences . Population declines can be reversed, as evidenced by the remarkable recovery of waterfowl populations under adaptive harvest management and the associated allocation of billions of dollars devoted to wetland protection and restoration, providing a model for proactive conservation in other widespread native habitats such as grasslands. [citations omitted]
When faced with such devastating news, pleas for conservation may appear Panglossian. Yet that’s not entirely so. Rosenberg provided some grounds for cautious optimism, according to the Cornell Chronicle: :
There are a few bright spots for birds. Among the population models, raptor populations – hawks, eagles and other birds of prey – have tripled since 1970. The study’s authors said that uptick is attributable to government regulations that banned the harmful pesticide DDT and made shooting raptors illegal.
Waterfowl populations have grown 50% in the past 50 years. The scientists said that’s due to dedicated programs such as the North American Waterfowl Management Plan and its billions of dollars invested into wetlands conservation and international collaboration, as well as the establishment of a federal no-net-loss wetlands policy.
Rosenberg, a faculty fellow at the Atkinson Center for a Sustainable Future, said the success in wetlands conservation for waterfowl may provide a blueprint for turning around the steep declines among grassland birds. Even if 30% of North America’s birds are lost, there are still 70% left to spur a recovery if conservation measures can be implemented. But conservation action must come soon, he said.
“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.”
Andrew Holland, a spokesperson for the Nature Conservancy of Canada, concurs on the need for conservation and connects climate change to habitat loss. He also mentions the role played by free-roaming domestic cats. Over to the CBC:
“When you look at those numbers, clearly it’s a signal that there needs to be more conservation of lands that protect the habitats for the birds that are remaining so that they have a fighting chance of bouncing back.”
Habitat loss and climate change are among the major factors impacting the decline of bird populations.
Free-roaming domestic cats, collisions with glass, pesticide use and a decline in insects are also factors, he said.
Holland suggested that people leave their cats indoors.
“A lot of lands have been lost — wetlands, forests, coastal shoreline areas have been lost to erosion, storm surges, development and subdivisions,” said Holland.
So, in addition to the other massive catastrophes we must address – climate change, plastics, to name just two – add bird conservation measures to the list. The roots of each: untrammelled consumption. We know what must be done. Are we up to the task? Over again to the NYT:
The sheer scale of the bird decline meant that stopping it would require immense effort, said [Hillary Young, a conservation biologist at the University of California, Santa Barbara, who was not involved in the new research]. Habitats must be defended, chemicals restricted, buildings redesigned. “We’re overusing the world, so it’s affecting everything,” she said.