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habitat loss
'Catastrophic and Saddening': Research Shows US Butterfly Population Dropped 22% in Two Decades
"It's pretty shocking, really, that we've lost that much biodiversity in such a short time," said one of the study authors.
Mar 06, 2025
A landmark study released Thursday in the journal Science found that the number of butterflies in the United States declined dramatically between 2000 and 2020.
"The prevalence of declines throughout all regions in the United States highlights an urgent need to protect butterflies from further losses," according to the abstract of the study, which was authored by over 30 researchers from around the country.
Between 2000 and 2020, total butterfly abundance in the contiguous United States fell by 22% across 554 recorded species. The study also reported widespread species-level decline, in addition to overall abundance decline. According to researchers, 13 times as many butterfly species are declining as they are increasing.
"It's pretty shocking, really, that we've lost that much biodiversity in such a short time," said Eliza Grames, a conservation biologist at Binghamton University in New York and one of the study authors, who spoke with WBUR about the findings.
The survey used data from multiple sources, including North American Butterfly Association, which is the "longest-running volunteer-based systematic count of butterflies in the world," as well as data from Massachusetts Butterfly Club, which "carries out organized field trips and records individuals' reports across the state in which participants identify and record butterflies seen."
Scientists and dedicated amateur enthusiasts helped collect the data, according to The Washington Post, which spoke with some of the researchers.
"Scientists could not get all the data we used," Nick Haddad, an ecologist and conservation biologist at Michigan State University who worked on the study, per the Post. "It took this incredible grassroots effort of people interested in nature."
The study identified pesticide use, climate change, and habitat loss as drivers of the decline.
The research echoes other scientific findings that have recorded widespread loss of insect abundance more generally, a phenomenon that's sometimes called the "insect apocalypse." Bugs do many important things, like pollinating crops and keeping soil healthy. "As insects become more scarce, our world will slowly grind to a halt, for it cannot function without them," wrote biologist Dave Goulson in 2021.
Entomologist David Wagner, who was not involved in the study, told the Post in an email that butterflies function as a "yardstick for measuring what is happening" among insects generally. He said the findings of the study were "catastrophic and saddening."
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Human Activity Pushing More Than 1 in 5 Migratory Species Toward Extinction: UN
"The global community has an opportunity to translate this latest science of the pressures facing migratory species into concrete conservation action," said one U.N. official.
Feb 12, 2024
As world governments gathered in Uzbekistan Monday for the United Nations conference on migratory species, they centered the theme "Nature Knows No Borders"—an idea that a new landmark report said must take hold across the globe to push policymakers in all countries and regions to protect the billions of animals that travel each year to reproduce and find food.
The Convention on the Conservation of Migratory Species of Wild Animals (CMS) marked the opening of the 14th Conference of the Parties (CMS COP14) to the United Nations biodiversity treaty by releasing the first-ever State of the World's Migratory Species report, showing that nearly half of migrating species are declining in population.
The crisis is especially dire for more than 1 in 5 species that are threatened with extinction, and 70 species listed under the CMS which have become more endangered, including the steppe eagle, the Egyptian vulture, and the wild camel.
The populations of nearly all species of fish listed in the U.N. treaty, including sharks and rays, have declined by 90% since the 1970s.
The two biggest drivers of endangerment and threatened extinction are overexploitation—including incidental and intentional capture—and habitat loss, and both are directly caused by human activity.
Seven in 10 CMS-listed species are threatened by overexploitation, while 3 in 4 of the species are at greater risk of dying out due to habitat loss, as humans expand energy, transportation, and agricultural infrastructure across the globe.
The climate crisis and planetary heating, pollution, and the spread of invasive species—thousands of which are introduced by humans—are also major threats to migratory species, the report says.
"Unsustainable human activities are jeopardizing the future of migratory species—creatures who not only act as indicators of environmental change but play an integral role in maintaining the function and resilience of our planet's complex ecosystems," said Inger Andersen, undersecretary-general of the U.N. and executive director of the U.N. Environment Program (UNEP). "The global community has an opportunity to translate this latest science of the pressures facing migratory species into concrete conservation action. Given the precarious situation of many of these animals, we cannot afford to delay."
Migratory species "reinforce" the fact that nature does not observe borders put in place by humans, Andersen added in a video posted on social media, and humans must work across borders to ensure these species are protected.
According to the report, nearly 10,000 of the world's key biodiversity areas are crucial for the survival of migratory species, but more than half are not designated as areas that must be conserved—and 58% are under threat due to human activities.
Mapping and taking adequate steps to protect "the vital locations that serve as breeding, feeding, and stopover sites for migratory species" is a key priority, said the CMS in a statement.
"Migratory species rely on a variety of specific habitats at different times in their lifecycles," said Amy Fraenkel, CMS executive secretary. "When species cross national borders, their survival depends on the efforts of all countries in which they are found. This landmark report will help underpin much-needed policy actions to ensure that migratory species continue to thrive around the world.”
In addition to increasing understanding of migration paths and minimizing human infrastructure in the pathways, the report recommended that policymakers "strengthen and expand efforts to tackle illegal and unsustainable taking of migratory species"; scale up efforts to tackle climate change and light, noise, chemical, and plastic pollution; and consider expanding CMS listings to include more at-risk migratory species in need of international attention.
"There are many things that are needed to be done on addressing the drivers of environmental change, such as agriculture for habitat destruction, the sprawl of cities, we have to look at rail, road, and fences," said Fraenkel. "One of the most important things for migratory species is something we call ecosystem integrity: they need particular sites to breed, feed, and travel. If those sites cannot be accessed or don’t exist any more, then it's obviously going to be detrimental."
The report focused on 1,189 migratory species identified by the U.N. as needing protection, but found that another 399 migratory species are either threatened or near threatened with extinction.
"People might not realize that whales, lions, gorillas, giraffes, and many birds are migratory species," Fraenkel said.
At the opening ceremony of CMS COP14, Andersen called on policymakers to live up to the conference's theme "by ensuring free passage of migratory species and by ensuring that, through multilateralism, we reach a hand across every border to ensure long-term sustainability, for people and for planet."
Reversing population decline is possible, the report emphasized, pointing to coordinated local action in Cyprus that reduced illegal bird netting by 91% and "hugely successful" conservation and restoration work in Kazakhstan, "which has brought the saiga antelope back from the brink of extinction."
"I ask parties to consider how to work in harmony with other processes for mutually assured success," said Andersen, "all in the interests of sustainable economies and societies."
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'Very Bad News': Human Activities Increased Extinction Rate of Species Groups by 35 Times
"What we're losing are our only known living companions in the entire universe," one study author said.
Sep 19, 2023
In what researchers call a "biological annihilation," human activities are driving entire groupings of vertebrate species to extinction at a rate 35 times what it would have been without human interference.
The study, published in the Proceedings of the National Academy of Sciences Monday, found that 73 genera—the next thickest branch from species on tree of life—had been lost since A.D. 1500. Without the mass exploitation of the natural world that took off around that date with European colonization, the number lost in the past 500 years would have been only two, and it would have taken 18,000 years to reach 73 extinctions.
"Such mutilation of the tree of life and the resulting loss of ecosystem services provided by biodiversity to humanity is a serious threat to the stability of civilization," study co-authors Paul Ehrlich of Stanford University and Gerardo Ceballos of the National Autonomous University of Mexico wrote in the abstract.
Or, as Ehrlich summarized it in all caps on social media, "New approach to extinction crisis, very bad news."
Previous attempts to grapple with the sixth mass extinction had focused on the number of species lost or at risk. But looking at genera can provide a clear view of the "magnitude and impact" of these losses, the study authors wrote.
Why? Because when one species dies, other species in the same genus can fill its niche in the ecosystem and preserve much of its genetic code, Ceballos told Stanford News. However, when a genus disappears, it leaves a larger gap in both the ecosystem and the genetic record—one that it can take evolution tens to millions of years to fill.
For example, when the passenger pigeon genus went extinct in 1914, the white-footed mouse lost its main food competitor. This combined with a decrease in large predators caused white-footed mouse populations to explode, which has been fatal for humans, because white-footed mice are the primary carriers of Lyme disease.
"We are alarmist because we are alarmed."
"By losing all these genera, we are losing the foundations of the planet to have life in general and human life in particular," Ceballos told The Guardian.
There's also an inherent sadness to the disappearance of so much unique life.
"What we're losing are our only known living companions in the entire universe," Ehrlich told Stanford News.
Ceballos and Eherlich expected genera extinction rates to be lower than species ones, but found in fact that they were about the same. The pair looked specifically at birds, mammals, reptiles, and amphibians. Beyond the 73 extinct genera, the planet also lost 10 families and two orders: the elephant bird and the New Zealand moa. Birds overall lost the most genera, with mammals coming in second.
What's more, if the climate emergency, the illegal wildlife trade, and habitat loss continue and all endangered genera go extinct by 2100, their extinction rate would jump to 354 times what it would have been without these human actions.
"People say that we are alarmist by saying that we expect a collapse," Ceballos told The Guardian. "We are alarmist because we are alarmed."
However, both authors emphasized that it was not too late to act.
"As dramatic as the results are, what is important to mention is that we still have time," Ceballos added. Though he noted that "the window of opportunity is closing rapidly."
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