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These reviled birds of prey literally save people’s lives

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Friday, August 2, 2024

A vulture in India in 2022. The country saw its native vulture population fall from tens of millions to only a few thousand in the 1990s, with terrible effects for the human population. | Faisal Khan/Anadolu Agency via Getty Images As a young man in the 1990s, walking to school in New Delhi, Anant Sudarshan would watch the vultures perched along telephone wires, waiting for the discards of nearby leather tanning factories. So when the birds started to disappear, he couldn’t help but notice. What Sudarshan, who now researches environmental policy and economics at the University of Warwick in the UK, did not realize at the time but would help discover decades later, was that the extinction of India’s vultures had far-reaching consequences for the humans who lived alongside the birds. In just a few years, the species’s disappearance contributed to the deaths of hundreds of thousands of his fellow citizens. Together with Eyal Frank, an environmental economist at the University of Chicago, Sudarshan used his adolescent experience as inspiration for a new study being published in the American Economic Review. As in other developing nations, they found, the scavengers functioned as a natural sanitation system for communities with a less developed infrastructure than the US or Europe, helping control diseases that could otherwise be spread through the carcasses they consume. Outside experts unaffiliated with the study say it will be a classic that unlocks further research on how the loss of critical species can have disastrous effects on human populations that depend on them, in often underappreciated ways. The findings should reshape how the public and policymakers alike relate to the world around us, and how we consider the unforeseen consequences of ecological destruction.  “We’re interconnected with the rest of the natural world,” Frank said. “I think for a lot of people, it’s this hippie, quasi-tree-hugger concept. Turning it into numbers and an outcome that people care about like mortality does change how people think about this statement: that we’re one with nature. What does that actually mean? It’s not a spiritual statement. It’s a statement about causal mechanisms.” The human costs of India’s extinct vultures Sudarshan and Frank estimate that from 2000 to 2005, an additional 500,000 people died in India above the preexisting trend, after the rapid dying off of vultures in the 1990s. The near-extinction was an unexpected (and for a long time unknown) byproduct of the country’s farmers introducing a medication to livestock that had previously only been prescribed to humans. Within a few years, 95 percent of the country’s vulture population was wiped out, dropping from tens of millions to a few thousand. A decade later, researchers discovered the drug led to kidney failure and death in the vultures when they fed on dead livestock that still had it in their system. Sudarshan and Frank compared death rates in the years following the die-offs between regions that had previously been home to vulture populations and those that hadn’t, finding that people started dying at higher rates in areas where the birds had lived. In the communities that lost vultures, there were an estimated 104,000 excess deaths annually — deaths that may be attributed to the species’ near-extinction — from 2000 to 2005, the years immediately following their dramatic decline that were the focus of Sudarshan and Frank’s study. It adds up to more than half a million deaths over five years, costing India an estimated $69 billion annually. “I would not have guessed the effect would be so large,” Sudarshan said. But as he and Frank came to realize the various vectors by which diseases might spread without vultures around, Sudarshan realized the extinction was “the largest sanitation shock you could imagine, where you have 50 million carcasses every year not being disposed of.” Keystone animal species are vital to human health Ecologists and conservationists have long known that some species — called “keystone” species — play a pivotal role in their ecosystems. Scientists have also suspected that those species’ role is so important that their loss could have life-and-death consequences for human beings. That relationship, though, has been hard to prove. There has been plenty of circumstantial evidence. In India, vultures are known to be extremely efficient scavengers, eating nearly all of a carcass less than an hour after finding it. Before the extinction, Indian regions that were home to vultures already recorded lower baseline mortality rates than those without them. After the birds died off, people in affected areas reported seeing more feral dogs and more rotting carcasses building up in fields. Without vultures to consume them, there were more dead animals lying around, which sometimes ended up in rivers or other bodies of water, tainting local water supplies. The absence of vultures became an opportunity for other scavengers, such as rats and dogs. India did not attempt a census of feral dogs until 2012, well after the study period. But when they did, there were more of the animals in the areas previously hospitable to vultures, which Sudarshan and Frank argue implies the dogs may have flourished after the birds were eliminated.  Dogs and rats are less efficient than vultures at fully eliminating flesh from potentially disease-carrying carcasses, creating more opportunities for a person to come in contact with infected remains. They’re also more likely to transmit diseases like anthrax and rabies to people. Orders of the rabies vaccines started to rise in the years after the vulture population plummeted.  “I was mind-blown that it happened so drastically, so quickly,” Frank said. “We often say that anecdotes are not evidence, but the amount of anecdotes about how people were negatively affected by the disappearance of the vultures, we read more and more and more of it and said, ‘Okay, this has got to show up in data.’” Sudarshan and Frank have now provided a template for studying the impacts of species loss on human health, and researchers unaffiliated with the study told me that they expect more such research to follow.  Frank hopes future work might be able to identify whether specific causes of death increase after the elimination of a keystone species. Rethinking our relationship to the animals we live alongside The findings should inform conservation efforts in other regions, such as sub-Saharan Africa, where vultures play a similar sanitation role, the researchers argue. Small investments to support local populations could have big payoffs. More broadly, supporting species believed to be ecologically critical, of which vultures are only one, is a wise investment.  It is also clear that farmers and agricultural officials should consider the potential ripple effects when giving new medications to livestock. This is a textbook example of One Health, the public health paradigm that says we should protect animal and environmental health to protect the well-being of humans.  The drug in question, diclofenac, had been introduced because it was a cheap way to treat fevers and inflammation in farm animals. The medicine was banned once Indian officials learned of its role in the vulture die-off, but by then, the damage was already done.  Vultures remain critically endangered in India, with only a few thousand individuals. Sudarshan and Frank argue their findings should encourage conservation efforts in India, though vultures’ life cycles will make them difficult to restore: They lay, at most, one egg in a year and take years to sexually mature. The enormous consequences of their near-extinction in India remind us that promoting biodiversity means embracing every species, not only those that look good on a T-shirt; they and we are all part of a whole. “We need to really remember these connections. They are crucially important,” Andrea Santangeli, a conservation scientist at the Research Centre for Ecological Change at the University of Helsinki, told me. “We cannot live a healthy life without a healthy nature.” A version of this story originally appeared in the Future Perfect newsletter. Sign up here!

As a young man in the 1990s, walking to school in New Delhi, Anant Sudarshan would watch the vultures perched along telephone wires, waiting for the discards of nearby leather tanning factories. So when the birds started to disappear, he couldn’t help but notice. What Sudarshan, who now researches environmental policy and economics at the […]

A vulture in India in 2022. The country saw its native vulture population fall from tens of millions to only a few thousand in the 1990s, with terrible effects for the human population. | Faisal Khan/Anadolu Agency via Getty Images

As a young man in the 1990s, walking to school in New Delhi, Anant Sudarshan would watch the vultures perched along telephone wires, waiting for the discards of nearby leather tanning factories. So when the birds started to disappear, he couldn’t help but notice.

What Sudarshan, who now researches environmental policy and economics at the University of Warwick in the UK, did not realize at the time but would help discover decades later, was that the extinction of India’s vultures had far-reaching consequences for the humans who lived alongside the birds. In just a few years, the species’s disappearance contributed to the deaths of hundreds of thousands of his fellow citizens.

Together with Eyal Frank, an environmental economist at the University of Chicago, Sudarshan used his adolescent experience as inspiration for a new study being published in the American Economic Review. As in other developing nations, they found, the scavengers functioned as a natural sanitation system for communities with a less developed infrastructure than the US or Europe, helping control diseases that could otherwise be spread through the carcasses they consume.

Outside experts unaffiliated with the study say it will be a classic that unlocks further research on how the loss of critical species can have disastrous effects on human populations that depend on them, in often underappreciated ways. The findings should reshape how the public and policymakers alike relate to the world around us, and how we consider the unforeseen consequences of ecological destruction. 

“We’re interconnected with the rest of the natural world,” Frank said. “I think for a lot of people, it’s this hippie, quasi-tree-hugger concept. Turning it into numbers and an outcome that people care about like mortality does change how people think about this statement: that we’re one with nature. What does that actually mean? It’s not a spiritual statement. It’s a statement about causal mechanisms.”

The human costs of India’s extinct vultures

Sudarshan and Frank estimate that from 2000 to 2005, an additional 500,000 people died in India above the preexisting trend, after the rapid dying off of vultures in the 1990s. The near-extinction was an unexpected (and for a long time unknown) byproduct of the country’s farmers introducing a medication to livestock that had previously only been prescribed to humans.

Within a few years, 95 percent of the country’s vulture population was wiped out, dropping from tens of millions to a few thousand. A decade later, researchers discovered the drug led to kidney failure and death in the vultures when they fed on dead livestock that still had it in their system.

Sudarshan and Frank compared death rates in the years following the die-offs between regions that had previously been home to vulture populations and those that hadn’t, finding that people started dying at higher rates in areas where the birds had lived.

In the communities that lost vultures, there were an estimated 104,000 excess deaths annually — deaths that may be attributed to the species’ near-extinction — from 2000 to 2005, the years immediately following their dramatic decline that were the focus of Sudarshan and Frank’s study. It adds up to more than half a million deaths over five years, costing India an estimated $69 billion annually.

“I would not have guessed the effect would be so large,” Sudarshan said. But as he and Frank came to realize the various vectors by which diseases might spread without vultures around, Sudarshan realized the extinction was “the largest sanitation shock you could imagine, where you have 50 million carcasses every year not being disposed of.”

Keystone animal species are vital to human health

Ecologists and conservationists have long known that some species — called “keystone” species — play a pivotal role in their ecosystems. Scientists have also suspected that those species’ role is so important that their loss could have life-and-death consequences for human beings. That relationship, though, has been hard to prove.

There has been plenty of circumstantial evidence. In India, vultures are known to be extremely efficient scavengers, eating nearly all of a carcass less than an hour after finding it. Before the extinction, Indian regions that were home to vultures already recorded lower baseline mortality rates than those without them. After the birds died off, people in affected areas reported seeing more feral dogs and more rotting carcasses building up in fields.

Without vultures to consume them, there were more dead animals lying around, which sometimes ended up in rivers or other bodies of water, tainting local water supplies. The absence of vultures became an opportunity for other scavengers, such as rats and dogs. India did not attempt a census of feral dogs until 2012, well after the study period. But when they did, there were more of the animals in the areas previously hospitable to vultures, which Sudarshan and Frank argue implies the dogs may have flourished after the birds were eliminated. 

Dogs and rats are less efficient than vultures at fully eliminating flesh from potentially disease-carrying carcasses, creating more opportunities for a person to come in contact with infected remains. They’re also more likely to transmit diseases like anthrax and rabies to people. Orders of the rabies vaccines started to rise in the years after the vulture population plummeted. 

“I was mind-blown that it happened so drastically, so quickly,” Frank said. “We often say that anecdotes are not evidence, but the amount of anecdotes about how people were negatively affected by the disappearance of the vultures, we read more and more and more of it and said, ‘Okay, this has got to show up in data.’”

Sudarshan and Frank have now provided a template for studying the impacts of species loss on human health, and researchers unaffiliated with the study told me that they expect more such research to follow.  Frank hopes future work might be able to identify whether specific causes of death increase after the elimination of a keystone species.

Rethinking our relationship to the animals we live alongside

The findings should inform conservation efforts in other regions, such as sub-Saharan Africa, where vultures play a similar sanitation role, the researchers argue. Small investments to support local populations could have big payoffs. More broadly, supporting species believed to be ecologically critical, of which vultures are only one, is a wise investment. 

It is also clear that farmers and agricultural officials should consider the potential ripple effects when giving new medications to livestock. This is a textbook example of One Health, the public health paradigm that says we should protect animal and environmental health to protect the well-being of humans. 

The drug in question, diclofenac, had been introduced because it was a cheap way to treat fevers and inflammation in farm animals. The medicine was banned once Indian officials learned of its role in the vulture die-off, but by then, the damage was already done. 

Vultures remain critically endangered in India, with only a few thousand individuals. Sudarshan and Frank argue their findings should encourage conservation efforts in India, though vultures’ life cycles will make them difficult to restore: They lay, at most, one egg in a year and take years to sexually mature.

The enormous consequences of their near-extinction in India remind us that promoting biodiversity means embracing every species, not only those that look good on a T-shirt; they and we are all part of a whole.

“We need to really remember these connections. They are crucially important,” Andrea Santangeli, a conservation scientist at the Research Centre for Ecological Change at the University of Helsinki, told me. “We cannot live a healthy life without a healthy nature.”

A version of this story originally appeared in the Future Perfect newsletter. Sign up here!

Read the full story here.
Photos courtesy of

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Humans are killing off the old and wise animals that hold nature together. Here’s what must change

Like big, tall trees in old-growth forests, older animals are irreplaceable. Pulling them out leaves the ecosystem less resilient to future shocks. It’s time for ‘longevity conservation’ measures.

Laxmikant Ameenagad, ShutterstockIn humans and other animals, ageing is generally associated with a decline in biological function. But scientists are now discovering older animals perform vital roles in populations and ecosystems. Unfortunately, however, old animals can suffer the most from human activity such as over-fishing and trophy hunting. And the value of old, wise animals is not usually considered when we manage animal populations and seek to protect biodiversity. Our new review, published today in Science, draws on evidence from around the world to argue for a new approach called “longevity conservation”. The loss of old and wise animals has devastating global consequences. Clearly, more must be done to prioritise their survival. Benefits of a long life Cold-blooded (ectothermic) animals such as fish and reptiles tend to keep growing throughout their life. This means older individuals are generally larger than younger individuals. Being bigger has benefits, especially when it comes to feeding and reproduction. It’s widely known the number of offspring increases with age in fish and many other ectotherms. But it’s only recently been discovered that older mothers of some fish and sea turtles produce exponentially more offspring as time goes on. Their young may also have better chances of survival. Survival rates are can be higher in offspring from older mothers in other species too. For example, in birds older parents and their helpers often provide more food and better habitat for their chicks, improving fledgling survival rates. Females from a range of species tend to select older males as mates. These males commonly assume crucial social roles, such as leading long distance movements like migration, and regulating social structures, such as reducing aggressive behaviour. These behaviours influence decision-making with direct consequences for group and offspring survival. Large estuarine crocodiles like this one from Roper River, Northern Territory were hunted almost to extinction within Australia, but now they are a recovering conservation success. Church Missionary Society Australia With age comes wisdom Some animals draw on experience accumulated over the course of their lifetime in order to make better decisions. In elephants, mothers and grandmothers are repositories of knowledge. This “grandmother effect”, first studied in humans, also occurs in whales. Wise grandmother killer whales, which no longer reproduce, help their families find food when it is scarce and this benefits survival. In a wide range of species, new research is showing how older individuals transmit their knowledge to others via a process called cultural transmission. The benefits of old age extend to animals such as migratory birds, pack-hunting carnivores, and even fish. For example, taking all the big fish from some populations has diminished their collective group memory often needed for migration and knowledge of spawning areas. This family group of African elephants has been the subject of research into older animals. Phyllis Lee Examining the loss of older animals Our research set out to build understanding of the ecology and conservation of old animals. We assembled an interdisciplinary team of experts who work on different animals and diverse ecosystems. Our team included behavioural and wildlife ecologists as well as freshwater, marine and fisheries scientists. We searched the literature and wrote a review. In addition, we used a machine learning topic model to delve into more than 9,000 peer-reviewed papers. Most research has focused on the negative aspects of ageing, particularly in humans, and short-lived animal models such as fruit flies. Yet emerging evidence is showing how old wild animals contribute to populations and ecosystems. Many of these functions benefit people too, but are being lost as old individuals are removed from the wild. Fishing has caused a systematic decline in the abundance of old fish, with these aged individuals reduced in 79-97% of the ocean populations examined. Old African elephants and other trophy animals are commonly poached or hunted, both legally and illegally. But the loss of old individuals is not limited to large enigmatic species. Deep-sea coral and Antarctic sponges – which can live for thousands of years – are being harvested, damaged by fishing gear, and affected by climate change. These species cannot be replaced within our lifetime. Species that live to advanced ages are often large, slow-growing, and slow to mature. These traits can make these species more vulnerable to extinction if older adults are killed by humans. But when humans spare old individuals, these long-lived species are more resistant to environmental change and provide more stable ecosystem services, such as fisheries which supply protein to feed the world. Retaining old animals tends to protect populations from poor environmental conditions such as drought and other extreme climate events, allowing species to persist against the odds. This buffering capacity is increasingly important in the face of global climate change. Very old animals, like this 100+ year-old bigmouth buffalo, are declining because of over-harvesting and river regulation. This species is native to rivers of North America. Alec Lackmann Introducing ‘longevity conservation’ Old animals play vital roles in the maintenance of biodiversity and ecosystem services. Yet harvest management and conservation practices tend not to focus on preserving age structures within populations. And the loss of old individuals is not yet recognised by the International Union for Conservation of Nature as a means of listing threatened species, or as a type of over-fishing. To protect old individuals and maintain or restore the age structure of wild populations, we propose “longevity conservation” measures. Decisive new policy and actions are needed to protect and restore the crucial ecological roles and services old, wise, and large animals provide. For example, formally recognising and avoiding “longevity overfishing” should be incorporated into fisheries management to help ensure the long-term sustainability of fisheries. Biodiversity conservation and threatened species policies should protect age structure. This is particularly important in long-lived species that produce more offspring with age, or where migration, social networks and cultural transmission of knowledge are required for survival. Keller Kopf does research on long-lived animals and has received grants associated with the management and conservation of fisheries and wildlife.

Animals
Conservation
Nature

Reduce whale-ship strikes by making 2.6% of ocean surface safer, study says

Researchers identify collision hotspots around world but reveal almost all these lack preventive measuresCollisions between whales and ships can prove fatal for the marine mammals, but researchers say expanding mitigation measures to just 2.6% of the ocean’s surface would reduce the chance of such strikes in all risk hotspots.While experts say many whale-ship collisions go unobserved and unreported, making it difficult to put a figure on the scale of the problem, some estimates suggest tens of thousands of the animals are killed each year. Continue reading...

Collisions between whales and ships can prove fatal for the marine mammals, but researchers say expanding mitigation measures to just 2.6% of the ocean’s surface would reduce the chance of such strikes in all risk hotspots.While experts say many whale-ship collisions go unobserved and unreported, making it difficult to put a figure on the scale of the problem, some estimates suggest tens of thousands of the animals are killed each year.Now researchers say they have not only identified hotspots where the risk of collisions is greatest, but revealed almost all of these lack measures to mitigate such strikes.Dr Jennifer Jackson, of the British Antarctic Survey and a co-author of the research, said: “This is the first study to look at this problem at a global scale, enabling global patterns of collision risk to be identified using an extremely large contemporary dataset of four recovering whale species.”Writing in the journal Science, the team report how they compiled a dataset of 435,000 whale locations, recorded between 1960 to 2020, for blue, fin, humpback and sperm whales.“These are four highly migratory species with a global distribution, that have shown evidence they are impacted by ship strikes, and have lots of sightings reports,” Jackson said. “They provide an opportunity to investigate this problem at a global scale.”The team then combined this dataset with more than 35bn positions from 175,960 ships to estimate the risk of whale-ship collisions across the world’s oceans.The results reveal that marine shipping occurs across 91.5% of the combined range of these whales, putting them at risk of collisions.The researchers were also able to identify hotspots – defined as areas with the top 1% of ship-strike risk.While these were mostly concentrated around continental coastlines, and the highest percentage was in the Indian Ocean, the researchers said hotspots were also found in areas of open sea such as the Azores, at least for blue and sperm whales.The researchers added that almost 5% of the hotspots affected three of the four whale species, with almost 20% affecting two of the species.“Over 95% of the risk hotspots for all species were found in exclusive economic zone (EEZ) waters, pointing to the importance of national regulation to reduce this risk globally,” said Jackson.When the team looked at ship-strike management measures, such as speed reduction zones or changes in vessel routes, they found levels of protection varied across hotspots.skip past newsletter promotionThe planet's most important stories. Get all the week's environment news - the good, the bad and the essentialPrivacy Notice: Newsletters may contain info about charities, online ads, and content funded by outside parties. For more information see our Privacy Policy. We use Google reCaptcha to protect our website and the Google Privacy Policy and Terms of Service apply.after newsletter promotionOverall, however, less than 7% of the risk hotspots for any of the four species were covered by voluntary measures, and less than 1% were covered by compulsory measures.Yet such interventions could have a big impact. “Full coverage of hotspots could be achieved by expanding management over only 2.6% of the ocean’s surface,” the team write, with Jackson noting that vessel slowdowns were the most effective way to reduce collision risk.While the threat of collisions has grown with increasing marine shipping, the team said the climate crisis could make the situation worse, noting declining sea ice in the Arctic could open new trade routes and result in whale populations moving northwards.Sally Hamilton, the chief executive of the charity Orca, and who was not involved in the research, said large whales were facing the equivalent of marine motorways.“The shipping industry have an opportunity to put vessel strike at the heart of their environmental strategy by working with conservationists and governments to establish safe marine spaces,” she said. “In doing so they can help undo the damage caused by industrial whaling and mitigate the future impacts of vessel strikes.”Dr Freya Womersley, of the Marine Biology Association, said the research emphasised that wildlife-ship collisions were a global issue and therefore required a global response.“It’s encouraging to see that targeted shipping management – over a relatively small ocean area – could achieve full strike-risk hotspot coverage, making positive conservation outcomes very achievable for these species,” she said.

Animals
Climate
Crisis

The Coyotes Arrived. Now, They’re Changing Angel Island.

Deer and raccoons that once fearlessly roamed the island, have become prey. The post The Coyotes Arrived. Now, They’re Changing Angel Island. appeared first on Bay Nature.

Just over a mile of water lies between Angel Island and the mainland town of Tiburon. During high winds and currents, kayakers tend to steer clear of this channel known as Raccoon Strait, which carries some of San Francisco Bay’s strongest and deepest waters. Nonetheless, some swimmers choose to fight the tides, including Olympians competing in the Tiburon Nautical Mile Swim, and a few furry, four-legged canines with a steadfast determination to reach an island buffet. For as long as California State Parks (CSP) staff can remember, they have never encountered coyotes on Angel Island. Then in 2017, a disbelieving ranger spotted a coyote, and then another one and another one. As the new top predator spreads across the 1.2 square mile island, the cascade of their effects on the local ecology is turning researchers’ heads. Scientists from the California Department of Fish and Wildlife (CDFW) collected data on the island this October, hoping to learn about the coyotes’ watery crossings and impact on the island deer population. “We do know coyotes have been expanding south into Marin County and to San Francisco. They’re already taking exploratory things like going across the Golden Gate Bridge,” says Brett Furnas, a CDFW quantitative ecologist. “So it’s not a stretch that they would, maybe by accident, get swept across to Angel Island, or intentionally do that.” Coyote swimming towards Tiburon from Angel Island this April, its head just barely visible (Left, Photo by Casey Dexter-Lee); Coyote getting its legs wet on the shores of Angel Island looking towards Tiburon (Right, Photo by California State Parks/Bill Miller) The idea of coyotes on Angel Island has been floated before. In 1915, the US Army introduced about 20 Columbian black-tailed deer (Odocoileus hemionus) to Angel Island for hunting, but stopped in the 1950s when the island became a state park. Over the next 50 years, the deer population exploded to as high as 300. It was the state’s highest documented density of deer—a record likely still standing in California.  “The deer were starving and skinny, and there was a concern for the impacts on the island’s cultural plants and vegetation,” says Bill Miller, a CSP environmental scientist. Native plants on the island that deer are known to feed on include sagebrush, chamise, and purple needlegrass. “There were all sorts of suggestions thrown out,” says Miller. “We could relocate some. We could introduce coyotes onto the island. We could maybe introduce contraceptives.” Angel Island fawns lounging in 2010 (Matt Baume via Flickr, CC by-SA 2.0); An Angel Island doe dashing across the street (Torroid via Flickr, CC BY-SA 2.0) Relocating coyotes to Angel Island was proposed in 1981 by Dale McCullough, a wildlife biologist and former professor at UC Berkeley. He advocated for bringing over a small pack of six coyotes to prey on the sick deer and fawns damaging the island’s trees and shrubs.   Native to California and most of the US, coyotes (Canis latrans) can survive almost everywhere, from dry deserts to foggy coasts. In the past fifty years, their numbers and range have expanded into sprawling cities and suburbs, where they feed on cats, small dogs, rats, trash, and fruit.   McCullough’s coyote proposal, however, fell flat. Originally in favor of the plan, the California Department of Fish and Game succumbed to the backlash from the public and animal rights groups, and withdrew the proposal to naturally control the deer population with predators.  “In the end, state parks went with a culling program, and over the years, it would cull deer every few years,” says Miller. “But then at some point, the culling stopped and the numbers of deer on the island apparently stabilized… Shortly after, the coyotes showed up.” Coyote perched on a rocky outcrop, and a nonchalant pair on the street looping around Angel Island (California State Parks/Michael Dolan) Parks employee Mikayla Smith first saw a coyote on the lawn of the Parks staff residences in 2017. But she was met with disbelief when Parks staff told her coyotes didn’t exist on the island. Her sighting was dismissed until another Parks employee, Andrew Luskus, caught a glimpse of one. When Luskus turned the corner on his bike along the four-mile fire trail that circles the island, he made split-second eye contact with a coyote, before it scampered into the bushes. “Are you sure it wasn’t a dog?” fellow Parks employees asked. He had seen many coyotes during his time as a Parks ranger in Death Valley—he was sure.  Within a year after Luskus’ sighting, Parks staff began hearing them. Ferry workers were seeing them. “I’ve seen coyotes swim across Raccoon Strait,” wrote Ashley Kristensen, the operations manager who has worked at the Angel Island-Tiburon Ferry for 15 years. Aaron Swerkes, a fifth-year ferry captain who has sailed in the Bay for the past thirty years, has seen coyotes in the strait just a couple times since his first sighting about a decade ago. The first litter of pups appeared in 2019. And with it, a trophic cascade—a domino effect that begins when top predators impact the behavior or abundance of their prey, trickling down to the rest of the food chain. Coyote pups in a redwood grove near the southern tip of the island on June 21, 2024 (Omar Babovic)Perhaps the most famous example of a trophic cascade is the reintroduction of gray wolves to Yellowstone National Park, after they were shot, trapped, and poisoned into extinction in the 1930s. Without their top predator, elk were unafraid in the open and as a result overgrazed on young brush and trees, leaving scientists concerned about erosion and plant die-off. From 1995 to 1996, the National Parks Service released thirty-one gray wolves to prey on the elk. In just five years, willow and aspen stands recovered along riverbanks. Beavers and other wildlife began to thrive, and even the course of the river itself changed as a result. At Angel Island, a similar cascade has begun. Now a menu item, deer timidly skirt among shrubs and bushes. “Around the time the last ferry left, the deer would come and hang out on the lawn in the visitors center,” says Casey Dexter-Lee, the State Parks Interpreter II who has lived on the island for 14 years. “Now, they aren’t in this open space as much and are a bit more cautious.” While bucks remain gallivanting the streets, armed with their antlers, fawn and doe are rarer sights. Since the litter’s arrival, Parks staff have not witnessed any deer grow into adulthood, according to Dexter-Lee, though it is possible that they were raised on remote, hidden parts of the island. “I do know that coyotes are eating deer and fawn,” says Miller. “Staff have told me that, and when we were out there last week, I found a deer hoof in coyote scat.”   Angel Island Parks Interpreter II Casey Dexter-Lee looking at some coyote scat on the road, and also, a buck (Jillian Magtoto) Raccoons, too, are no longer a common sight. They used to steal and beg from people, who were concerned about seeing them in the daytime, since it is usually a sign of sickness or rabies, says Dexter-Lee, Now, they’re no longer a problem. Dexter-Lee also wouldn’t mind if the coyotes kept the Norwegian rats under control, which arrived on 19th and 20th-century ships, and have since disrupted the growth of native plants and the wildlife that relies on them. Still, scientists and staff worry that one endemic species could suffer from predation: the Angel Island mole. It’s slightly larger than other East Bay moles with a broader nose, bigger feet, heavier front claws, and slightly darker coloring. “The Angel Island mole is a subspecies of mole that is only found on this island,” says Miller. “But I don’t know what their numbers are or if coyotes are eating them or not.” Raccoon in the brush of Angel Island in 2018 (l Rocky Ordoñez via iNaturalist, CC0); The pictured broad-footed mole (Scapanus latimanus) is found primarily in California and Baja California with at least 12 subspecies, including S.I. insularis on Angel Island. (Bob Dodge via iNaturalist, CC-BY-NC 4.0) As for change in island plant life, so far there isn’t any, says Dexter-Lee. But we can make some predictions. “With less grazing pressure we may see more diversity, an increase in non-resistant browse, and a denser forest with smaller and more abundant stems,” says Miller. For Angel Island, he adds, less deer may mean more oak trees. In a seemingly endless cornucopia of food options, the coyotes appear to live in an island paradise. They regularly munch the fallen fruit beneath the Catalina cherry and Canary Island date palm trees, enriching their varied omnivorous diet. Unrestricted by their crepuscular clock, they encounter visitors and staff at all hours of the day. Trails and roads are overrun by their scat. They loiter among picnic tables where visitors might leave behind crumbs. Since the first litter in 2019, Parks staff have observed small coyotes and pups every year. But the extent of their growth has limits. “There’s only so much food and space to support coyotes on an island,” says Furnas, who leads the CDFW’s investigation of coyote and deer populations on Angel Island. A coyote pounces and triumphantly snacks on an underground critter near the docks and Visitor’s Center picnic tables on Angel Island (Video by Jillian Magtoto)Since September, the CDFW has been collecting coyote scat and installing wildlife cameras to determine their genetics, diets, and movements. The island’s isolation presents a unique opportunity to learn how coyotes control deer populations in a closed environment, says Furnas.  He suspects the coyotes are doing so by feeding on fawns, whose first year of survival is often the most critical limitation for population growth. Whether the coyotes seek food and partners beyond the island, however, remains unknown.  “As long as there is enough food for them, do they stay on Angel Island, or do they go back to the mainland?” Furnas asks. “On islands, you can have genetic inbreeding… So for a healthy population, you’re going to want to have genetic mixing as well.” The CDFW hopes to provide deer and coyote population estimates within a year. Whether it plans to answer other questions of reproduction rates, genetic diversity, and interspecies dynamics depends on if the study continues in the future. But for now, if you find yourself gazing across Raccoon Strait from the island, mainland, or ferry, keep your eyes peeled for a coyote’s head bobbing in the water.

Animals
Extinction
Food

Should Offshore Oil Rigs Be Turned into Artificial Reefs?

Oil rigs around the world are habitats for marine species. When they stop producing oil, should they be removed or allowed to stay?

Even before I could make out the silhouette of Platform Holly on the foggy horizon, I could see and smell oil. Ripples of iridescent liquid floated on the sea’s surface, reflecting the cloudy sky. But the oil wasn’t coming from a leak or some other failure of the rig. Milton Love, a biologist at the Marine Science Institute at the University of California, Santa Barbara, explained that it was “kind of bubbling up out of the seafloor.” Our boat, less than two miles from the central California coast, was sailing above a natural oil seep where the offshore energy boom first began.For thousands of years the Chumash, an Indigenous group native to the region, identified these oceanic seeps and their naturally occurring soft tar, known as malak, which washed up on the shore. Sixteenth-century European explorers noted oil off the coast of modern-­day Santa Barbara, and in the 1870s the U.S. oil boom reached California. In the late 1890s the first offshore oil wells in the world were drilled from piers off of Summerland Beach; 60 years later the state’s first offshore oil platform was deployed to drill the Summerland Offshore Field.Since then, 34 other oil platforms have been installed along the coast, and more than 12,000 have been installed around the world. These hulking pieces of infrastructure, however, have finite lifetimes. Eventually their oil-producing capacities tail off to the point where it is no longer economically viable to operate them—that, or there’s a spill. Today 13 of California’s 27 remaining offshore platforms are what’s known as shut-in, or no longer producing oil.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.Platform Holly is among the dead platforms awaiting their afterlives. At the time of its installation in 1966, everyone knew a platform situated directly over a natural oil and gas seep was going to be a success. And for nearly five decades it was. Then, in 2015, a corroded pipeline near Refugio State Beach owned by Plains All American Pipeline cracked, spilling 142,800 gallons of crude oil into the Santa Barbara Channel. The spill killed sea lions, pelicans and perch, among other creatures; closed fisheries and beaches; and permanently severed Platform Holly from its market.Venoco, the oil company that owned Holly at the time, was not responsible, but it was bankrupted by the event. Because Holly is positioned within three miles of the coast, it was transferred into the hands of the California State Lands Commission (SLC) in 2017. The SLC is now responsible for managing the process of decommissioning the platform and determining its fate.Because Holly is already owned by the state, not an oil company, its transition could illuminate how to evaluate the fate of rigs worldwide based on science, not politics.According to platform-decommissioning consultant John Bridges Smith, a former leasing specialist with the Bureau of Ocean Energy Management who counts ExxonMobil, ConocoPhillips and Chevron among his clients, Holly and the eight other platforms whose leases are terminated or expired will be decommissioned by the end of the decade. Based on the original contracts between the oil companies and the state and federal governments, which date to the 1960s, this means the structures will have to be fully removed. In December 2023 the Bureau of Safety and Environmental Enforcement recommended that all 23 California platforms standing in federal waters be fully removed.Doing so will incur a great expense. That’s true everywhere but especially in California, where some of the platforms are in very deep water. According to one conservative estimate, completely removing all of California’s platforms would cost the responsible oil companies $1.5 billion. Smith says these companies would prefer to delay that process for as long as possible. Some environmental groups in California, meanwhile, are pushing to hold them to the speediest timeline.Platform Holly, located off the coast of Santa Barbara, Calif.Love, who has spent the past three decades studying the aquatic life that now calls southern California’s oil platforms home, would prefer a third alternative.In the decades since they were installed, the steel support structures of California’s oil platforms have become vibrant ecosystems isolated from fishing pressures—de facto marine sanctuaries. Rather than being removed, aging fossil-fuel infrastructure and its serendipitously associated habitats can be salvaged in the ocean as state-­managed artificial reefs. The entire topside—the above-water portion of steel, offices and cranes—and shallow section of a rig are removed, but part of the submerged base may remain. A pathway for doing so already exists in the U.S. and has been successfully followed 573 times in the Gulf of Mexico. Similar examples can be found around the world, from Gabon to Australia. Because Holly is already owned by the state, not an oil company, its transition could illuminate how to evaluate the fate of rigs worldwide based on science, not politics.When an oil platform is decommissioned, the process goes like this: First, in a phase known as plugging and abandoning, its oil wells are filled with concrete and sealed. Next, scientists conduct an environmental review and consider the various merits and risks of different removal strategies. The results determine a platform’s final resting place, which in most cases has been in a scrap metal yard. A platform’s support structure is called its jacket—hundreds of vertical feet of woven steel that is affixed to the bottom of the ocean. Most of the time engineers will use explosives to sever a platform jacket from the seafloor. The steel is then hauled to shore for disposal and recycling. Decommissioning is considered complete when a platform has been removed down to 15 feet below the mud line and the seafloor has been returned to preplatform conditions.Most of the offshore oil platforms that have ever been built were installed in the Gulf of Mexico—more than 7,000 since 1947. More than 5,000 of those have since been removed. In the 1980s oil companies and recreational fishing associations pushed for an alternative outcome that would both be cheaper and help to bolster struggling fish populations. In 1984 the U.S. Congress passed the National Fisheries Enhancement Act, providing for the creation of the National Artificial Reef Plan, which allowed oil platform operators to donate decommissioned rigs to states as “artificial reefs.”In the following years Texas, Louisiana, Mississippi, Florida and Alabama each passed the necessary legislation and established their own State Artificial Reef Programs. These were, and still are, funded by oil and gas contributions and the interest earned on those payments. The program hasn’t replaced full removals; between 1987 and 2017 only 11 percent of all decommissioned oil platforms off Louisiana were partially removed. But in deeper waters, the story is different: of the 15 structures decommissioned in depths greater than 400 feet, 14 have been partially removed, or “reefed.”Offshore oil infrastructure in California acts as a nursery for certain fish species.When a platform is partially removed, its topside is taken to shore. To avoid creating a navigational hazard, the first 80 to 85 feet of its jacket closest to the surface are either brought ashore or laid along the sea bottom. Finally, the remaining jacket—whether it is 15 feet of steel or hundreds—is either left in place or severed from the seafloor and towed to an approved reefing site. Liability for the reefed structure gets transferred from the oil company to the state, and the oil company donates 50 percent of its cost savings (from doing a partial removal versus a full removal) to the state. This process, colloquially referred to as rigs-to-reefs, has successfully bolstered fish populations in the Gulf.Ann Scarborough Bull, a U.C.S.B. biologist who studies the ecology of offshore oil platforms and renewable energy installations, worked in the Gulf of Mexico on offshore oil and gas regulation for 14 years. She arrived in 1975, when her husband took a job in the highly profitable offshore oil industry. When it came to oil platform ecology, “the Gulf of Mexico hadn’t been studied,” Bull says. She took a job as a chief scientist for the U.S. Minerals Management Service, which has since been reorganized into the Bureau of Ocean Energy Management, and received funding to research the communities of fish and invertebrates dwelling underneath the platforms. On her frequent trips offshore, it became clear to her that the rig jackets provided habitat that was vital to the region’s economy.Lutjanus campechanus, commonly known as the northern red snapper, is one of the most frequently caught species in the Gulf’s recreational fishing industry. A long-lived apex predator, it is mostly sedentary in its adult phase and restricted to reef habitats. Until the mid-20th century, the primary fishing grounds for red snapper were off the western coast of Florida and in the waters south of the Florida Panhandle.Just as populations in the fish’s historical range were being depleted by overfishing and trawling, red snapper began to shift and expand west across the entirety of the Gulf. Thousands of oil platforms were being installed across the northwestern and north-­central Gulf. Decades of research have shown that with natural reefs few and far between, red snapper were using the oil platforms as a kind of outpost, which allowed their population size to expand significantly.Imagine the Empire State Building extending up from the ocean floor, blossoming with mussels and scallops and sea anemones, providing food to legions of fish.As drilling operations multiplied, commercial and recreational reef-fishing industries grew in tandem. Surveys from the early 1980s indicated that one quarter of fishing trips were associated with oil and gas structures. “This whole society in the Gulf of Mexico grew up with two ways to make a living: one, be a fisherman, and the other, be connected with oil and gas,” Bull says.In 2001 Bull moved back to her native California, and she arrived at U.C.S.B. in 2016. Her experience studying the state’s platforms and coming to understand the surrounding politics has shown her that the differences in platform strategy between California and Louisiana are multifold. “There are factions, especially in Santa Barbara, that absolutely despise oil and gas companies,” Bull says. This animosity, she explains, makes the rigs-to-reefs process a harder sell.It’s not unwarranted. On January 28, 1969, a blowout at Union Oil’s Platform A in the Santa Barbara Channel spilled 100,000 barrels of crude oil into the Pacific Ocean. Black tar covered beaches for dozens of miles and killed thousands of birds and marine mammals. At the time, it was the largest oil spill in U.S. history.The spill prompted the first Earth Day and the creation of the U.S. Environmental Protection Agency. It also spawned numerous environmental nonprofits in the Santa Barbara region, including Get Oil Out! and the Environmental Defense Center. Development of new oil fields off the coast of California halted and didn’t resume until 1982.Then California’s first decommissionings began. In 1988 Texaco successfully removed Platforms Helen and Herman. In 1996 Chevron removed Platforms Hope, Heidi, Hilda and Hazel from the Santa Barbara coast—but not completely. The cuttings piles—­gigantic mounds of rock debris, mud, and other hydrocarbon detritus discharged by the drilling process—underneath all four platforms were allowed to remain.Linda Krop, now chief counsel for the Environmental Defense Center, was then a law clerk with the organization. The group wasn’t too happy that Chevron had seemingly gotten around the obligations of its original contracts, which required full removal of its platforms and restoration of the local environment to its natural condition.“I just think it’s criminal to kill huge numbers of animals because they settled on a piece of steel instead of a rock.” —Milton Love, biologistIn the nearly three decades since, Krop has worked as an attorney holding oil companies accountable for their environmentally destructive actions. She had her greatest court victory in 2016, achieving the termination of 40 federal oil leases offshore. Krop is firmly against the prospect of reefing off California. “The fish are going to be fine if the platforms go away,” she says. “They’re not going to disappear.”In July 2023 I visited Holly with Milton Love on an especially foggy morning. After a 30-minute boat trip from the Santa Barbara Harbor, its skeletal outline began to emerge from the mist. From a distance Holly resembled a skull with barred teeth and low, hollow eyes, but up close it was an eight-story scaffolding of steel beams, pylons and old shipping containers.Holly hasn’t produced oil for a decade, but the whirring and beeping of generators and cranes was still too loud to speak over. People in construction vests milled about the upper decks, ostensibly monitoring the wells’ recent plugging procedure and shoring up the platform. Brown sea lions were flinging themselves from the ocean onto the platform’s lower decks, howling and jostling for space. Love told me that what we were seeing was only a small piece of the action. The real story, he said, was hidden below the waterline, where the mechanical noise dims and is replaced by the crackle of shrimp and fish nibbling at the reef.The platform jackets are covered in millions of organisms and provide habitat for thousands of fish. Some of California’s 27 platforms are relatively small; Holly stands in only 211 feet of water. Others, such as the Exxon-­built Harmony, stand in depths up to 1,198 feet. Imagine the Empire State Building extending up from the ocean floor, blossoming with mussels and scallops and sea anemones, providing food to legions of fish. According to a 2014 paper co-authored by Love, these platforms are among the most productive marine fish habitats in the world and, per cubic meter of seafloor, are more productive than any natural reef.In 2019 the Gulf recreational fishing community took more than 50 million trips and caught 332.5 million fish. But recreational fishing off the coast of California is nowhere near as big. And because of the more than 120,000 acres of natural rock reef along the state’s coast and Channel Islands, the amount of habitat area generated by the rigs does not significantly alter the total regional habitat area or increase the carrying capacity of the fish population. In contrast, the Gulf platforms contribute 30 percent of their region’s total “reef” habitat area.Love argues that California’s platform ecosystems are vital for different reasons. After finishing his Ph.D. and landing at U.C.S.B. as a research biologist, Love received funding from the National Biological Survey; he wrote a book called The Rockfishes of the Northeast Pacific and set out to study how oil platforms functioned as fish habitats. “Most of the money has always been from the federal government,” Love says. But a “small percentage” came from Chevron and ExxonMobil.Love’s early work laid the foundations for others to research the structures as well. In a 2014 study, quantitative marine ecologist Jeremy T. Claisse, now at California State Polytechnic University, Pomona, and his colleagues revealed that along the coast of southern California, jacket habitats don’t just support millions of tunicates, barnacles, rock scallops and shrimp; they can be sites of fish production. That means many fishes living on and around the legs grow up there and may either spend the entirety of their lives at one platform or travel elsewhere, bolstering fish populations nearby.Sea anemones live on the shell mounds that form under the platform legs.Bocaccio and cowcod rockfish of southern California’s natural reefs are economically important and at one point were considered overfished. In 2006 Love found that California’s offshore oil platforms contribute 20 percent of the young bocaccio rockfish that survive each year across the species’ entire geographic range, which stretches from Alaska to Baja California. The platforms operate essentially as nurseries, he says, incubating the next generation.Mussels dominate the platform jacket in the first 40 feet of water, forming three-inch crusts around the submerged legs and beams. Barnacles and bivalves extend even deeper. When these creatures die or are dislodged by a storm, they sink to the feet of the gargantuan structures and form shell mounds up to 220 feet in diameter and rising upward of 20 feet from the seafloor. Both among the decaying shell mounds and throughout the crisscrossing beams of the platforms’ midwater sections, juvenile rockfish of the region proliferate.Trapped within these shell mounds, however, are the piles of toxic drill cuttings. Until the late 1970s, regulation to properly dispose of cuttings was fairly loose, and operators would often deposit the debris on the seafloor. In a 2001 study, surface sediments from the shell mound of Platform Hazel, installed in 1958, were found to be lethal to 50 percent of tested shrimp within 96 hours of exposure. Recently installed platforms don’t appear to have the same problem, perhaps because most cuttings must be hauled to shore. In one study, cuttings piles below platforms installed before stricter regulation were found to contain 100 times more volatile organic compounds than a newer platform, Gina, installed in 1980.Love and his colleagues wanted to know if the contamination from cuttings extended to the water column around the shell mound. In 2013 they published a paper that found California’s platforms—regardless of age—were not contaminating their associated fish populations. “We looked at fishes that live around platforms—not just Holly but throughout southern California—and compared the heavy metal concentrations with fishes of the same species on nearby natural reefs,” he says. “There was no statistical difference between what we saw.”Still, people like Krop at the Environmental Defense Center are not convinced any oil infrastructure should be allowed to stay in the ocean. “If we need to build some [more] artificial reefs, then let’s do it the right way,” she says. California has been building its own artificial reefs since 1958, when the state’s Department of Fish and Wildlife placed 20 automobile bodies in the waters of Paradise Cove off Malibu. Such artificial reefs tend to be spread over many acres in relatively shallow waters. Platform jacket reefs, in contrast, are not even technically artificial reefs and exist as habitats of extreme vertical complexity and dimension. They are smaller in area yet more productive on average.In 2003 Mark Carr of the University of California, Santa Cruz, wrote that there are few natural rock reefs at the depths of the California oil platforms and none with comparable physical characteristics. If the goal is to contribute to overall reef area, their value is “minuscule.” If, however, the intent is to preserve their unique habitats, their value is “100 percent.”Love has a more irreverent perspective on their value. “As a biologist, I just give people facts,” he says. “But I have my own view as a citizen, which is: I just think it’s criminal to kill huge numbers of animals because they settled on a piece of steel instead of a rock.”Many countries around the world are coming up on the decommissioning of their platforms for the first time. According to Amber Sparks of Blue Latitudes, a company that consults for governments worldwide regarding the environmental effects of their platform-decommissioning practices, there is no international standard for how an oil platform should be reefed.Globally, the process is often ad hoc. Off the coast of Gabon, for instance, high-biodiversity habitats underneath more than 40 active oil platforms are included in a system of marine national parks. In Malaysia, an oil platform has been converted into a resort for scuba divers. With the assistance of Chevron, Thailand established an artificial reef program and reefed seven platforms near Koh Pha-­Ngan in 2020. In waters off the U.K., five platforms have been approved for partial removal, but no full platform jacket has been reefed, and no rigs-to-reef program exists. A 2017 study evaluated the possibility of transforming one U.K. rig into a hub for harvesting wave energy.When a decommissioned platform is removed, so, too, goes habitat area for sea lions and certain fish species.According to Francis Norman, managing director of the nonprofit Center of Decommissioning Australia, there is large demand from recreational fishing communities for artificial reefs—at least off the coast of Western Australia, where more than 40 platforms are stationed in shallow waters. But in the eastern state of Victoria, 23 Exxon platforms in the Bass Strait are in depths up to 525 feet—these structures are too far from land to be seen over the horizon and are not fished because of rough water conditions.Norman says Australia does not have an official rigs-to-reef program, but in 2023 Exxon applied for permits to partially remove 13 of its platforms. The company, he says, withdrew its application this summer after a wave of media reports featured criticism of partial removal.As of August 2024, all of Holly’s 30 wells were fully plugged and abandoned. Jennifer Lucchesi, executive director of the California State Lands Commission, says the facility is being “hardened” so it won’t need 24-hour staffing as it moves into “caretaker” status. Now studies of Holly’s subsurface biology are looking at the platform’s effects on its local marine environment to inform the creation of an environmental impact report, which will review the likely net outcomes of full removal versus partial removal versus no action. The “biological study” component is being prepared by Love, Bull and their colleagues at U.C.S.B.Oil companies are interested in platform reefing because of money, not fish. Partial removal is far cheaper than full removal. Reefing the California platforms instead of eradicating them would net the companies a savings of $150 million and generate $600 million for the state. (Actual costs and savings for removal are likely to exceed these projections by at least a factor of four.) Still, not a single California platform operator has applied to begin the rigs-to-reef process. Smith believes the hesitancy results from differences in policy. Legislation in the Gulf States asks for 50 percent of an oil company’s cost savings to be paid to a state in most cases; in California, it’s 80 percent. And whereas in the Gulf liability transfers to the state, in California it essentially stays with the responsible oil company. Previous attempts, in 2015 and 2017, to amend the legislation in California failed. Krop says groups like hers “would not support making the state liable,” and Smith says that would make reefing “unworkable” for the oil companies. When approached for a comment, Chevron wrote: “We are still finalizing our decision on this issue.”Smith believes the most likely outcome for California’s aging offshore infrastructure will be not full removal or partial removal but indefinite delays. Operators are supposed to submit decommissioning plans two years before a lease ends, but operators for six offshore platforms whose leases ended in 2015 still have not followed through.Oil platforms were designed to be productive for 20 to 30 years, but some are still producing oil after 45 years. No one knows how long they might stand. In one scenario, maintenance may not be properly kept up. This isn’t hard to imagine: Platform Holly fell into a state of disrepair following its operator’s bankruptcy, and ExxonMobil, a prior operator, paid millions to refurbish the platform so it could support the equipment required to plug and abandon its dormant wells.In a soon-to-be-published paper on the topic of delay, Smith discusses a worst-case scenario in which poor maintenance and corroded steel cause a platform to collapse during an earthquake or storm. A pile of steel legs, crossbeams and submerged topside offices would rest like a shipwreck on the seafloor. Most of the midwater organisms would be gone, as would those associated with the lengthy vertical water column. But Love says organisms associated with complex bottom habitats would perhaps flourish. Rockfish and lingcod would swim around the jagged, anemone-covered pieces of broken platform legs and rusted steel, past scurrying crabs, exploring their reconfigured home.In another world, you could see oil companies keeping up with maintenance indefinitely. To prevent the steel legs from rusting and collapsing, they could continue applying zinc anodes to the steel bars, allowing the zinc to rust instead of the legs. “The marine habitat will change with climate change, of course, as everywhere will,” Love says. But the sea lions would stick around on the lower decks, as would the blacksmith damselfish in the shallow waters. The platforms’ topsides, steadfast off the Santa Barbara coast, would be a reminder of an oil-ridden past.

Animals
Climate
Energy

Horse Domestication Story Gets a Surprising Rewrite

Archaeological and genetic discoveries topple long-standing ideas about the domestication of equines

The world we live in was built on horseback. Many people today rarely encounter horses, but this is a recent development. Only a few decades ago domestic horses formed the fabric of societies around the globe. Almost every aspect of daily life was linked to horses in an important way. Mail was delivered by postal riders, people traveled by horse-drawn carriage, merchants used horses to transport goods across continents, farmers cultivated their land with horsepower, and soldiers rode horses into battle.Scholars have long sought to understand how the unique partnership between humans and horses got its start. Until recently, the conventional wisdom was that horses were gradually domesticated by the Yamnaya people beginning more than 5,000 years ago in the grassy plains of western Asia and that this development allowed these people to populate Eurasia, carrying their early Indo-European language and cultural traditions with them.Now new kinds of archaeological evidence, in conjunction with interdisciplinary collaborations, are overturning some basic assumptions about when—and why—horses were first domesticated and how rapidly they spread across the globe. These insights dramatically change our understanding of not only horses but also people, who used this important relationship to their advantage in everything from herding to warfare. This revised view of the past also has lessons for us today as we consider the fate of endangered wild horses in the steppes. And it highlights the essential value of Indigenous knowledge in piecing together later chapters of the horse-human story, when domesticated horses moved from Eurasia into the rest of the world.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.The genus Equus, which includes horses, asses and zebras, originated around four million years ago in North America. Over the next few million years its members began dispersing across the Beringia land bridge between what is now Russia and Alaska and into Asia, Europe and Africa. Horses are among humanity’s oldest and most prized prey animals. Perhaps the first indisputable evidence for hunting with weapons by early members of the human family comes from horse-rich archaeological sites such as Schöningen in Germany, dating to some 300,000 years ago. The unique lakeshore environment there preserved not only the remains of a band of horses but also the immaculately crafted wood spears that humans used to dispatch them. For millennia wild horses remained a dietary staple for early Homo sapiens living in northern Eurasia. People were keen observers of these animals they depended on for food: horses featured prominently in Ice Age art, including in spectacular images rendered in charcoal on the limestone walls of France’s Chauvet Cave more than 30,000 years ago.Horses served as muses for Ice Age people, who captured their likenesses in spectacular works of art, such as the images in France’s Chauvet Cave that date to more than 30,000 years ago.Heritage Images/Getty ImagesTracking the transition from this ancient predator-prey connection to early domestication—which includes such activities as raising, herding, milking and riding horses—can be challenging. Researchers studying the deep past rarely have the luxury of written documents or detailed imagery to chronicle changing relationships between people and animals. This is especially true in the Eurasian steppes—the cold, dry, remote grasslands where scientists suspect that the first horse herders emerged, which stretch from eastern Europe nearly to the Pacific. In the steppes, cultures have long been highly mobile, moving herds to fresh pastures with the changing seasons. Their way of life left behind archaeological assemblages that can be shallow, poorly preserved and difficult to study. Indeed, much of what we know about the origins of horse domestication comes from a single, powerful scientific source: the bones of ancient horses themselves.But it wasn’t until much later that people domesticated horses, as evidenced by burials at sites such as Novoil’inovskiy in Russia dating to the early second millennium B.C.E.As an archaeozoologist, I seek to understand the origins of domestication through the study of horse bones from archaeological sites. In the early days of this kind of scientific inquiry into domestication, some researchers looked for patterns in the size, shape or frequency of these bones over time. The basic logic behind this approach is that if horses were living in close contact with people, their bones might have become more widespread or more variable in shape and size than in earlier periods, whether because people were breeding them for particular traits or because they were putting the horses to work in ways that altered the animals’ bodies over the course of their life, among other factors.Burials of horses and chariots establish that early domesticated horses were used for transport.But it turns out that looking for these types of patterns in the archaeological rec­ord is a little bit like reading tea leaves. Changes in the shape or number of horse bones found at ancient sites could be caused by any number of other things, from environmental change to shifting human diets or even sampling errors. At best, these indicators give us only an indirect way to trace the origin of herding or riding.A stronger, more scientific understanding of horse domestication began to take shape in the 1990s. Building on the work of some earlier scholars, archaeologist David Anthony of Hartwick College in New York State and his colleagues identified direct evidence for domestication in horse remains, publishing their findings in Scientific American. When horses are used by people for transportation, they sometimes develop a particular pattern of damage on their teeth from the equipment that is used to control them. This damage, known as bit wear, can often be seen on the lower second premolar of horses ridden with metal mouthpieces, or bits. Anthony and his colleagues found bit wear in an ancient horse from a Ukrainian site known as Deriyevka, which was thought to have been home to an archaeological culture known as the Yamnaya people. Although the Deriyevka horse had not been directly dated, its association with the Yamnaya culture suggested that herders in the Eurasian steppes might have been raising and riding domestic horses by the fourth millennium B.C.E. or even earlier.The Deriyevka horse seemed to tie together a number of loose threads in scientists’ understanding of ancient Eurasia. Beginning after 6,000 years ago, during a period called the Eneolithic (also sometimes known as the Copper Age), large human burial mounds known as kurgans appeared across much of eastern and central Europe and the western steppes. Over the years many archaeologists and scholars hypothesized a connection linking kurgans, the spread of Indo-European languages and the first horse domestication. Specifically, they proposed that the Yamnaya people tamed horses in the Black Sea steppes and then swept across Eurasia on horseback, bringing their burial customs and an early form of Indo-European language—which is believed to have given rise to many languages spoken today, including English. On the heels of Anthony’s discovery, this framework, known as the kurgan hypothesis, gained wide currency in academic literature and popular consciousness.Unfortunately, the Deriyevka horse was not what it seemed. A decade later direct radiocarbon dating of the remains showed that the animal wasn’t nearly as old as Anthony thought. Instead it had lived and died sometime in the early first millennium B.C.E., when domestic horses and horseback riding were already widespread and well documented. But rather than rejecting the kurgan hypothesis entirely, archaeologists continued to explore other animal-bone assemblages from the western steppes dating to around the same period, searching for horse bones to validate the idea. During this search one site in particular drew renewed interest: Botai, located in northern Kazakhstan.Botai sits some distance east of the Yamnaya homeland. Despite lacking any obvious cultural connections to the Yamnaya, Botai is also located in the western steppes, and like Deriyevka, it dates to the fourth millennium B.C.E. Most interesting, the animal-bone assemblage recovered from excavations at Botai contained huge numbers of horses. In fact, among thousands of animal bones from Botai, almost all were from horses. Working with these materials, archaeologists began to discuss the relevance of Botai’s horses to the question of early domestication.Early on, the Botai domestication debate was a spicy one. First Anthony and his colleagues suggested that the strange surface shape of some Botai teeth was also a form of bit wear, hinting that the Botai horses were ridden. Soon, though, Sandra Olsen, now at the University of Kansas, identified the same features in wild horses, meaning they could not be taken as proof of domestication on their own. Scholars also looked at contextual aspects of the Botai site, including the architectural layout, speculating that post holes and backfilled pit houses filled with organic material could be leftover traces of corrals and corral cleaning.Still, other scientists remained skeptical—for good reason. Some Botai horses were found with harpoons directly embedded in their ribs, obviously killed by hunters. An even bigger problem with connecting Botai to domestication, though, was the age and sex patterns among the animals found at the site. In a managed herd of horses, those chosen for slaughter are either very young or very old because breeding-­age animals are needed to ensure the herd’s fertility and survival. Marsha Levine and her colleagues pointed out, however, that Botai’s bone assemblage consisted mainly of the remains of mostly healthy adults. Moreover, the site contained large numbers of breeding-age females, as well as some fetal and neonatal horses from pregnant mares. The slaughter of these animals would be devastating to the fertility of a domestic herd, but evidence of it is common in archaeological sites where wild animals were hunted for food.This healthy disagreement over domestication at Botai was temporarily quashed in 2009, when a high-­profile publication in the journal Science brought together new evidence apparently showing that people from Botai milked and rode horses. The authors looked at the shape of the bones of horses at Botai and argued they were similar to the modern domestic horse, Equus caballus. Using emerging techniques for the study of ancient biomolecules, scientists also analyzed ceramic shards from Botai and found residues that seemed to have come from ancient horse fats. These residues, though not diagnostic of milk on their own, had anomalous isotope values, suggesting they could have originated from milk.The most important new argument, though, was that some Botai horses displayed a different kind of tooth damage that the researchers said could be more securely linked to use of a bridle. With new results from Botai strengthening con­fidence in the idea of horse domestica­­tion during the fourth millennium B.C.E., the kurgan hypothesis returned to paradigm status.In the decade and a half since Botai revived the kurgan hypothesis, our archaeozoological tool kit for understanding ancient horses has grown by leaps and bounds. And one by one these new techniques and discoveries have begun to erode the connections between Botai and horse domestication. In a recent study, my colleagues and I analyzed dozens of wild horses from Ice Age sites across North America. Our research showed that the key features interpreted as evidence of bridle and bit use at Botai were probably the result of natural variation rather than horse riding or horse equipment.Moreover, we now know that many other aspects of horse riding can leave a recognizable signature in an animal’s teeth and bones. Halters, saddles and harnesses can make distinctive marks. And different activity patterns, from heavy exertion to confinement, also have identifiable impacts. For instance, the pressure from mounted riding or from pulling a carriage or chariot can each cause unique problems in a horse’s vertebral column or lower limbs. Even early veterinary practices such as dentistry are sometimes visible in the archaeological rec­ord. So far none of these more reliable indicators of domestication have been found in Botai horses.Horses from the site of Botai are now known to have belonged to a wild horse species, Przewalski’s horse, that was hunted for food. Conservation efforts are currently underway to restore this highly endangered species.Sven Zellner/Agentur Focus/ReduxWe can also look to DNA for clues. Improvements in ancient-DNA sequencing now allow scientists to reconstruct partial or whole genomic sequences from archaeological remains. Analysis of DNA from ancient people and animals has yielded some rather remarkable findings, documenting, for example, the migration of Yamnaya people from eastern Europe as far east as Siberia and Mongolia during the late fourth millennium B.C.E. These same techniques have shown no evidence of interaction between Yamnaya people and Botai, however.Likewise, new techniques for recovering ancient proteins from human dental plaque have shown no evidence of horse milk in the diet of the people who lived at Botai. In fact, horse milk apparently didn’t become widespread in western Asia until the first millennium B.C.E., 3,000 years after the Yamnaya and Botai.The most devastating blow to the kurgan hypothesis came accidentally from a 2018 genomic study by Charleen Gaunitz of the University of Copenhagen, Ludovic Orlando of the Center of Anthropobiology and Genomics of Toulouse in France and their colleagues that showed Botai horses were not the ancestors of domestic horses at all. Rather they were members of another horse species that still survives today, known as Przewalski’s horse. Przewalski’s horse is a close relative of domestic horses but one that has never been managed as a domestic animal in recorded history.Recent archaeological and genetic insights into horse domestication have relevance for understanding the horse human relationship today. Discoveries of an ancient saddle and other tack in Mongolia show that steppe cultures helped to invent technology that is still in use.Some scientists remain convinced that Botai has some connection to early domestication but now suggest that the site represents an earlier, failed effort at taming and control of Przewalski’s horse. In their 2018 study, Gaunitz and her colleagues went so far as to argue that modern Prze­walski’s horses might be the escaped descendants of domesticated Botai horses, a conclusion that many others in the scientific community felt was unsupported.The Botai debate has had important real-­world impacts for Przewalski’s horse. In the 20th century Przewalski’s horses went extinct in the wild, and zoo populations dwindled almost to the single digits. In recent decades these horses have returned from the brink through a careful captive-breeding program, and they have been reintroduced into some areas of Central Asia. This past June a new band of Przewalski’s horses from the Prague Zoo was released into the grasslands of central Kazakhstan, marking the first return of this species to the region in two centuries.In the long term, the success and funding of such conservation projects may hinge heavily on public support, making it imperative to get the story straight. Media attention around Botai has sometimes generated headlines suggesting that Przewalski’s horses “aren’t wild after all” and are instead domestic escapees. Narratives like these are no longer supported by the archaeological data and can imperil ongoing protection, conservation and restoration of habitat for this highly endangered species.Despite some lingering controversy over Botai, the available data emerging from new scientific approaches to studying the past paint a much clearer picture of horse domestication than we’ve ever had before. The recent spate of genomic sequencing and radiocarbon dating of horse bones from across Eurasia has all but disproved the kurgan hypothesis. Such data show us that important cultural developments in the fourth millennium B.C.E.—including the Yamnaya migration and the dissemination of kurgans and Indo-­European culture—probably took place many centuries before the first horses were domesticated, aided by the spread of other livestock such as sheep, goats and cattle and the use of cattle to pull wagons. Meanwhile many steppe people still hunted wild horses for meat.New genomic analyses led by Pablo Librado of the Institute of Evolutionary Biology in Barcelona and Orlando indicate that the ancestors of modern domestic horses originated in the Black Sea steppes around 2200 B.C.E., nearly 2,000 years later than previously thought. Although we do not yet know exactly the details of their initial domestication, it is clear based on the timing that these horses belonged to post-Yamnaya culture. Patterns in the ancient genomes suggest that in the early centuries of domestication, the horse cultures of the western steppe were selectively breeding these animals for traits such as strength and docility.Horses have figured prominently in the traditions and values of the Lakota and many other Native Nations across the Great Plains and Rockies.Courtesy of the Global Institute for Traditional SciencesThis revised timeline for horse domestication is part of a growing body of evidence that casts the Yamnaya legacy in a new light. Early Indo-European cultures such as the Yamnaya are sometimes portrayed in popular culture in a nationalist manner, with links drawn between their supposed domestication of the horse, impressive transcontinental migrations, and cultural dominance. Now science indicates that the Yamnaya probably didn’t domesticate horses at all, and their migrations were not necessarily heroic conquests. For example, new genomic data show that by around 5,000 years ago Yamnaya migrants reached as far as central Mongolia, where they are known as the Afa­nasievo culture. Although these migrants may have helped spread sheep, goats and cattle into East Asia, initially it seems their impact was limited to a few mountain regions of the eastern steppe. After the Yamnaya arrival, it would be almost 2,000 years before horses showed up in the region. And genomic analyses suggest that their Afanasievo descendants had little lasting genetic effect on later populations.The revelation that people domesticated horses much later than previously thought resolves what was always a nagging problem with the kurgan hypothesis. If horses were domesticated in the Eneolithic, why did it take centuries for much of their impact to show up in the archaeological record? Under the kurgan model, researchers often framed horse domestication as a gradual development to explain why it took so long for horses to move beyond the steppes and revolutionize trade and conflicts, for instance. When we look at our records of the past with this revised time frame for horse domestication in mind, there appears to be the rapid, disruptive and dynamic development we expected to see after all.In our new understanding it seems that almost as soon as people tamed horses, they began using them for transport. Some of the earliest robust archaeological evidence of horse domestication comes from burials of horses paired with chariots dated to around 2000 B.C.E. at sites associated with Russia’s Sintashta culture. Radiocarbon-dating and genetic records show that within only a few centuries domestic horses spread over huge swaths of the Eurasian continent. In some cases, their expansion was peaceful: as availability of horses grew across the steppes, new people incorporated horses, herding and transport into their way of life. In other instances, domesticated horses reached new locales through destructive conquests by marauding charioteers. Some cultures riding this wave of horse-drawn expansion were Indo-European; others weren’t.A nomadic family corrals livestock on horseback in Central Mongolia.Timothy Allen/Getty ImagesBy the middle of the second millennium B.C.E., horsepower had reached civilizations from Egypt and the Mediterranean to Scandinavia in the north and Mongolia and China in the east. In many cases, the arrival of horses upended the balance of power. For example, when horses first arrived in China during the late Shang dynasty, around 3,200 years ago, they were mostly a novelty for the elite. But within little more than a century a rival power, the Western Zhou, was able to marshal its strength and skill in chariotry to bring a dramatic end to Shang rule. In very short order, horses went from being a steppe curiosity to the foundation of authority for one of the largest civilizations of East Asia.In addition to clearing up these early chapters of the human-horse story, scientific archaeology has also uncovered connections between the horse cultures of the distant past and our world today. Archaeological discoveries and genomic data from the steppes and deserts of Central Asia are revealing the ways that horses and horseback riding helped humans form networks, trade routes and empires linking the ancient world in new ways.On horseback, people traveled steppe networks and the Silk Roads to move goods, plants, animals, ideas and even early pandemic diseases across Eurasia and beyond. These emerging transcontinental connections can be directly observed in the archaeological record. In Mongolia, a royal tomb from the early steppe kingdom of the Xiongnu dating to somewhere around 100 B.C.E. was found to contain a silver plate with a picture of the Greek demigod Hercules on it. Historical records document expeditions from China to Central Asia’s Ferghana Valley in search of horses, an early step in the formation of the Silk Roads trade routes, and during the height of the Tang Dynasty, a thriving trade sent horses from the Tibetan Plateau and the Himalaya to lowland China in exchange for tea. Recent DNA sequencing of the plague-­causing bacterium Yersinia pestis suggests that the earliest strains of the virus that devastated Europe first emerged deep in deserts, mountains and steppes of Central Asia before spreading along the horse-powered steppe corridors and Silk Roads in the early 14th century.The corridors and connections that ancient equestrians forged persist today: Ancient travel routes across the Mongolian steppe are now receiving makeovers with Chinese financing to serve as high-speed highways for motor vehicle transit. Even the state highway I take for my daily commute in Boulder, Colo., got its start as a 19th-century postal road.New archaeology discoveries show that steppe cultures helped to invent or spread important technologies that improved control over horses and are still used today. In Mongolia, my collaborators and I have discovered immaculately preserved ancient tack from some 1,600 years ago. This riding technology, which includes a wood frame saddle and iron stirrups, shows that steppe cultures helped to develop these equestrian devices, which gave riders greater seat stability and the ability to brace or stand in the saddle—significant advantages when it came to mounted warfare. These tools became a standard part of horse equipment in cultures all over the world, from the caliphates of Islam to the Viking explorers of the high Arctic.Archaeological science also allows us to trace the spread of domesticated horses out of Eurasia as people transported them to such places as the Sahel savanna of Africa, the Great Plains of North America, the Pampas of South America, and even island nations of Australasia and the Pacific, where horses shaped cultures across more recent periods. This work is showing some surprising results.Recently I worked with a large team of scientists, scholars and Indigenous knowledge keepers to see what archaeology, genomics and Indigenous knowledge systems could tell us about the history of domesticated horses in the U.S. The prevailing view among Western scientists was that Native American peoples did not begin caring for horses until after the Pueblo Revolt of 1680, when Pueblo people in what is now New Mexico overthrew Spanish colonizers. Through our collaboration we found that Native nations from across the Plains and Rockies adopted horses at least a century earlier than was ever chronicled in European historical records. This finding confirms perspectives preserved in some oral traditions and Tribal histories and mirrors our scholarship from similar archaeological contexts in Patagonia.Many Indigenous horse cultures, for whom a connection with horses is a source of strength, resilience and tradition, are now drawing on collaborative and interdisciplinary archaeological scholarship in their efforts to correct narratives, conserve traditional horse lineages and secure a place for horses in our changing world.In many ways, the disappearance of horses from daily life in the past century has been as rapid and jarring as their initial domestication 4,000 years ago. In most corners of the world speedy mechanization has replaced trails with pavement and horse transport with engine-powered or electric alternatives. These days, along the Front Range of the Rockies, people wearing jeans and cowboy hats once designed for life in the saddle are more likely to be found shopping at Whole Foods than slinging lassos.But the threads linking our ever changing present to the distant past are never far if you know where to look. Resolution of some of the most urgent problems of the 21st century—from saving endangered species to conserving cultural knowledge and traditions—will require a clear-headed and scientifically grounded understanding of the millennia-long relationship between human and horse.

Animals
Conservation
Culture

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