Showing posts sorted by relevance for query VULTURES. Sort by date Show all posts
Showing posts sorted by relevance for query VULTURES. Sort by date Show all posts

Sunday, October 04, 2026

Reintroduction of vultures to France causes friction with farmers

France’s vulture population is growing, thanks to a reintroduction campaign that began in the 1980s after the birds all but disappeared decades earlier. But according to some farmers, the return of the birds has brought challenges as well as rewards.


Issued on: 04/10/2026 - RFI

Griffon vultures arrive at a feeding station managed by the LPO Grands Causses, July 2026. © Sarah Elzas/RFI


By:  Sarah Elzas


Watching vultures feed is an impressive sight. Dozens of birds with wingspans of up to two metres descend simultaneously on to an animal carcass, jostling to get as close as possible.

“It's a real melée, a real scrum. They really go in on each other, they jump on each other’s backs. Anything goes,” says Robert Straughan, looking down over the edge of a cliff at a clearing 100 metres below, where he has just sent a sheep carcass on a zip line pulley.

Straughan, who is vulture project director for the League for the Protection of Birds (LPO) in the Grands Causses – an area of high limestone plateaus and deep river gorges in France's highland Massif Central region – collects sheep carcasses from farmers three times a week and brings them here, and to another feeding site in the Tarn River gorge.

Listen to a report on vultures in the Grands Causses on the Spotlight on France podcast, episode 150.
Spotlight on France, episode 150 © RFI

While most farmers in France use a collection service to remove the carcasses of dead animals, which takes them to an industrial rendering plant, in the Grands Causses 120 farms have vulture feeding sites, where they leave carcasses on their land for the birds to consume.

A handful of farmers in the area also work directly with the LPO, which collects their carcasses within 48 hours.

“We're doing work which even the farmers don’t necessarily like doing – dragging the carcasses about and things like that,” Straughan says.

He holds up a scope to scan the birds feeding below, looking for those with identification rings on their legs.

“These vultures know this area. They more or less know when to come, and they know there's no danger. They'll come in really close to us, which doesn't really usually happen. But here they know that we pose no threat to them,” says Straughan.


Robert Straughan looks for vultures in the cliffs along the Jonte river gorge, July 2026. © Sarah Elzas/RFI


'Bad press'


While there is no threat today, throughout the 19th and early 20th centuries people shot and poisoned vultures, which were viewed with suspicion, associated with death and decay.

Vultures can eat dead animals at almost any stage of decomposition, thanks to their highly acidic stomachs which kill most microbes and viruses.

“Vultures get a bad press. Everybody thinks, ‘oh, vultures... death, dirty birds’... even in the way they are portrayed in art,” Straughan says.

“But when you look into vultures and you understand how they function and the important role they play in cleaning an ecosystem, the role they play with farmers, you find that they're quite wonderful birds – even if they're not always that pretty, depending on whose eyes you look through.”

By the 1940s, vultures had all but disappeared from France.

Then in 1976 the government designated the griffon vulture a protected species, and a few years later conservationists, working with farmers in the Grands Causes, began work on a reintroduction programme.

The region boasts the ideal conditions for the birds: craggy limestone cliffs for nests and plenty of sheep farms to provide a food source.

Between 1981 and 2006 around 300 griffon vultures were reintroduced. Today there are more than 1,200 breeding pairs in the Grands Causses, or two-thirds of the population in France.
Vultures in the trees at the LPO feeding station on the Grands Causses, July 2026. 
© Sarah Elzas/RFI


Success decided by species

Griffon vultures feed primarily on soft tissue, and are usually the first to arrive at a carcass. The three other European vulture species have had less success. There are fewer than 40 breeding pairs of black vultures, which feed on skin and tendons, and three breeding pairs of Egyptian vultures, which pick meat from between bones.

There are no breeding pairs of bearded vultures, which eat the bones themselves.

Straughan notes the presence of two black vultures at the feeding site, a few minutes after the first scrum of griffon vultures.

"They come in usually second. They're a bit stronger and they bust their way on to the carcass and get the parts they want.”

“They're very, very effective,” he notes, as the vultures strip the carcass in less than 10 minutes.


After eating, the vultures head to a nearby tank of water.

“After the feed they really like to go and have a drink and a bath as well, and usually you'll see them sitting on the rocks with their wings open, a bit like cormorants, to dry off,” explains Straughan.

However, this is a cause of tension with farmers. The area’s porous limestone does not retain water, so farmers provide troughs for their sheep to drink from – which attract the vultures.

“That's problematic because afterwards the sheep won't drink, and so the farmer has to change the water regularly,” Straughan says. “But we work with the farmers and try to find systems to make the troughs less attractive for the vultures.”

Solutions such as floating covers have been introduced, and they are becoming increasingly necessary as the vulture population grows.
Attacks on animals

Water use is not the only point of friction. There have been reports from farmers that vultures have attacked animals they believe were still alive at the time.

The first reports appeared in the early 2000s, and authorities in Aveyron, Lozère and other departments have since put in place phone numbers for farmers to call in the case of suspected attacks.

An inspector is then dispatched, sometimes accompanied by a vet, to determine the cause of death.

Lilia Damian, who is in charge of relations with farmers at the LPO, says in the vast majority of cases the conclusion was that the animals were already dead when the vultures arrive. Attacks on live animals are “very unusual”, she says.

“They are on animals that are consistently very weak, with a very low life expectancy. It’s not just an animal that’s a bit tired and not moving much.”

A 2018 report by researchers from France’s then national wildlife agency, the ONCFS, found that of the 156 suspected attacks reported over the previous seven years, 63 involved vultures.

In 15 of those cases, vultures arrived before the animals died, and either accompanied or worsened the animals’ decline but did not cause the deaths.

“Griffon vultures do not have the physical capacity to prey on a live animal,” Damian says. “Their beaks are not very powerful. It is the same with the legs. Compared with an eagle’s talons, they are not powerful or able to grasp. They are really just adapted for walking, and they cannot hold on to an animal.”

However, she adds that the growth in population means the birds arrive faster, sometimes before a farmer can locate the dying animal.

“Because they forage in groups, their searches are inevitably becoming more efficient. They arrive faster at a carcass. Before it could take several hours, which gave the farmer time to notice. That’s not necessarily the case anymore. The animals are also consumed more quickly.”

However, she says the number of suspected vulture attacks has not increased, even as the vulture population has risen dramatically.

A balanced relationship


Nonetheless, Damian says these concerns colour how people view the birds, which can be an issue when it comes to conservation efforts.

Farmers’ unions and representatives have called for limits on the vulture population, which the LPO argues is not the right approach, arguing that natural limits on food and habitat will regulate the population.

“When people talk about there being too many, I often ask: ‘compared to what?’,” says Damian. “Ecologically, a population is limited either by its habitat or by its food supply. If we reach a point where there isn’t enough food for all the vultures, there will be higher mortality. So the population will hit a plateau and self-regulate based on the available food.”

For now, as farmers continue to use their feeding stations or the LPO’s collection service, there is sufficient food and the griffon vultures are doing well.

“There are for sure a lot of griffon vultures now, more than before. The population is doing well, and the reintroduction has been a success. That said, other species are in a completely different state of conservation,” says Damian.

Unlike similarly reintroduced predators such as wolves and bears, vultures depend on humans – and can also be quite useful to them.

“It's almost entirely down to the good relationship which we have with farmers, and their willingness to use the vultures as a way of a carcass disposal system, if you like,” says Straughan. “It's a big benefit for them and it's a big benefit for the vultures too.”

Saturday, August 31, 2024

 

Like people, vultures get set in their ways and have fewer friends as they age



Older birds tend to have more selective friendships with stronger bonds and may know better where to find food



University of California - Los Angeles





Key takeaways

  • Young griffon vultures move frequently between sleeping sites in different locations, interacting with many friends.
  • They get set in their ways as they age and roost in the same spots with the same individuals; older vultures follow the same paths.
  • Roosts act as information hubs; older vultures may have a more thorough knowledge of where to find food resources and less need to learn about them from other vultures.

If you’d rather be watching TV on your couch than dancing at the club, you might have something in common with aging griffon vultures. New research shows that young griffon vultures move frequently between sleeping sites in different locations and interact with many friends but get set in their ways as they age, roosting in the same spots with the same individuals. As moving between roosts becomes a grind, older vultures follow the same path, establishing movement routines, that are not seen in young vultures.

Younger vultures shy away from the most popular roosts, suggesting they might be intimidated by the older ones or that there’s a vulture equivalent of “Hey you kids, get off my lawn.”

The research, published in Proceedings of the National Academy of Sciences, shows that like many people, older vultures tend to have fewer, more selective friendships with stronger bonds. They may also have a more thorough knowledge of where to find food resources.

Eurasian griffon vultures, or Gyps fulvus, are large vultures that live in the Mediterranean, the Middle East and India. With wingspans up to 9 feet, they’re much larger than North American turkey vultures and bigger than bald eagles.

Finding food can be tricky for vultures because it depends on locating animal carcasses — an unpredictable and ephemeral source. When griffon vultures find a carcass, they tend to sleep or roost nearby and feed on it over a period of days. Roosting sites can thus be ‘information hubs,’ where vultures that recently fed signal to others about food sources; they then follow each other to carcasses and form friendships that help them stay in the loop about food.

The researchers wanted to know if an individual griffon vulture’s movement patterns and social behavior changed over the course of its life. They used GPS data from 142 individually tagged birds in Israel gathered over a period of 15 years to cross-reference the vultures’ ages with their movement and social interactions at roost sites.

“What we found was as they age, their loyalty to certain roost sites increases,” said co-author Noa Pinter-Wollman, a UCLA professor of ecology and evolutionary biology. “Young vultures check out many different roosts but in middle age, they start going repeatedly to the same places.”

The study showed young vultures sometimes returned to the same roost but usually chose different ones, rarely spending two nights in the same place. From young adulthood at around 5 years old through middle age, they spent about half their nights at the same “home” site and half elsewhere. In old age, they became true homebodies.

“When they are old, from the age of 10 onward, they no longer have the energy to be ‘out and about’ and return consistently to the same site,” said corresponding author Orr Spiegel of Tel Aviv University. “Those who were adventurous at the age of 5 became more sedentary by age 10.”

As the vultures grew older, the strength of their social bonds decreased as well for at least part of the year. The number of individuals they interacted with didn’t change with age — if they had five friends when young, they still had five when older. But the amount of time they spent with vultures outside of their close friend group plummeted. Older vultures spent most of their time with and roosted mostly with these close friends. Their movements also became more routine, eventually following a predictable pattern.

The study is unique because the researchers were able to track the movements and social behaviors of the same vultures for up to 12 nearly consecutive years over a 15-year period.

“We are able to show that the trends of individuals becoming more loyal to the same sites with age is not because the more exploratory individuals die earlier and live shorter lives, and the older, more sedentary individuals live longer lives,” said first author and Tel Aviv University postdoctoral fellow Marta Acácio. “Individuals actually change their behavior with age, and this has rarely been shown in nature for long-lived birds due to the difficulty of tracking individuals for such a long time.”

The research backs up findings from studies in other species that, with age, animals become more faithful to their known sites and routines — and potentially become more selective in their social relationships. These behaviors are commonly attributed to aging in humans and can help improve understanding of how animal populations move about in their environments and relate to other members of their species, as well as identify better ways to protect them from threats. For griffon vultures, this could mean better protection of important roosting sites and using knowledge about their social interactions to reduce the risk of poisoning.

“It looks like they just get set in their ways,” Pinter-Wollman said. “They’ve gathered information over the years, and they might as well use it. Carcasses are hard to come by and roosts are information hubs. Some roosts become popular for a reason; for example, they tend to be closer to reliable food sources and older vultures potentially monopolize these roosts.”

Monday, May 19, 2025

COOPERATION, NATURALLY


Working Together When Searching For Food Has More Benefits Than Trade-Offs For Vultures



White-backed and Rueppell's vultures in Uganda (photo by Jon A. Juarez)

By 

Together, or not together, that is the question. Hamlet is not the only one facing life-changing questions – wild animals have to make decisions pivotal to their survival on a daily basis.


In a modelling case study, scientists of the GAIA Initiative investigated whether exchange of information among African white-backed vultures (Gyps africanus) bring more advantages than disadvantages to the individual vulture in its search for food. They found that social foraging strategies are overall more beneficial than non-social strategies, but that environmental conditions such as vulture and carcass densities greatly influence which strategy yields the best results.

In a paper published in the journal “Ecological Modelling” the GAIA team led by first author Teja Curk from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) modelled how different foraging strategies perform under different ecological conditions and compared findings with field observations. They calculated, among other variables, the searching efficiency (the time needed to find the carcass and proportion of population that found the carcass), the scavenging efficiency (the proportion of food left in the environment) and the degree of competition for resources (the number of vultures converging on a single carcass).

To do this, they built agent-based models for three different foraging strategies: non-social foraging, where every vulture relies on spotting carcasses in the landscape by itself; the “local enhancement” strategy, where vultures are attracted by directly observing conspecifics that are feeding in addition to detecting carcasses on their own; and the “chain of vultures” strategy, where vultures also sequentially follow other vultures in the sky that are potentially on their way to a carcass site.

Vultures are social and communicative – and find food more easily this way

The agent-based models were built and verified using data collected from 30 tagged vultures in Etosha National Park in Namibia, from which more than 26 million GPS positions and corresponding ACC bursts (acceleration data) were included in this evaluation. ACC sensors record small movements of the tag in three dimensions and allow fine-scale behaviours to be analysed. The GAIA scientists applied their own machine learning algorithms to classify the GPS and ACC data and identified feeding behaviour of the vultures and subsequently carcass locations in the landscape.

“In our models we compared the three strategies with the empirical data from Namibia and were thus able to reliably calculate parameters such as the searching efficiency”, explains Curk. “We found that both social strategies outperformed the non-social approach in terms of searching efficiency, as individuals located carcasses more quickly compared to the non-social model. The ‘chain of vultures’ is especially beneficial when there are many vultures in an area that can coordinate search efforts by transferring information over great distances”.


Effective ‘word of mouth’ can lead to overcrowded feeding locations

The evaluations also revealed that a chain of vultures comes with a trade-off, since it often results in large congregations of vultures at carcass sites which could reduce individual food intake. In contrast, the local enhancement strategy balanced moderate searching efficiency with reduced competition.

Comparisons of scavenging efficiency showed that with only few vultures in an area, the amount of potential food left in the environment is quite similar in social and non-social strategies. With higher vulture densities, both social strategies surpass the non-social approach to a similar degree. Only at very high vulture densities did the scavenging efficiency of the “chain of vultures” fall short of “local enhancement” – with very long vulture chains concentration on few feeding sites becomes frequent and many individuals feed on only a small number of carcasses, leaving others unoccupied.

Protection for the highly endangered vulture species is urgent and important

The authors conclude that vultures in the study area likely adopt diverse foraging strategies influenced by environmental variables such as vulture and carcass densities. This behavioural flexibility suggests that vultures can optimize their foraging success by adjusting their reliance on social information in response to changing ecological conditions. However, the confirmed benefits of social foraging strategies underline the importance of vulture conservation: when vulture densities fall below a certain threshold, there are not enough vultures to use social information.

The searching and scavenging efficiencies drop and a notable amount of food remains undetected, further raising the challenges for vultures to feed, reproduce and, by extension, survive. From a vulture conservation perspective, it is therefore crucial to understand how environmental conditions shape foraging strategies and what are the associated costs and benefits.

In recent decades, the populations of many vulture species have declined sharply and are now acutely threatened with extinction. The main causes are the loss of habitat and food in landscapes shaped by humans as well as a high number of direct or indirect incidences of poisoning. The population of the white-backed vulture, for example, declined by around 90 percent in just three generations – equivalent to an average decline of 4 percent per year.

The conservation status of the African white-backed vulture was reassessed from “least concern” to “near threatened” in the 2007 IUCN Red List. Only five years later, the species was further “upgraded” to “endangered” and in October 2015, its status was changed to “critically endangered” as the actual, continuing decline was more severe than previously expected.



Eurasia Review

Eurasia Review is an independent Journal that provides a venue for analysts and experts to disseminate content on a wide-range of subjects that are often overlooked or under-represented by Western dominated media.

Sunday, January 12, 2020




Latest trouble at the border: Vultures are defecating and urinating all over a CBP radio tower
The mess is coating the entire 320-foot tower in southern Texas that the agency needs to communicate. The birds are also vomiting onto buildings below the tower and dropping prey from hundreds of feet in the air, an agency spokesperson said.


 
Hooded vultures wait for scraps of meat at Bissau's main slaughter house on November 26, 2019. - Tens of thousands of Hooded Vultures flock to the city of Bissau to in search of food left behind in heaps of garbage or around market areas. Photo by JOHN WESSELS / AFP

A radio tower for the US Customs and Border Protection near the US-Mexico border has been plagued by vultures that roost there and drop feces, vomit, and even prey on the buildings below.
Around 300 vultures have taken over the tower in the past six years, Quartz reports, and have coated the structure with "droppings mixed with urine," as well as corrosive vomit that eats away at the metal.CBP spokesperson told Quartz that the birds create a "terrifying and dangerous" environment at the workplace, and said there are anecdotes of them dropping prey from as high as 300 feet in the air.The Migratory Bird Treaty Act prohibits killing the vultures, but CBP is planning to install a "viable netting deterrent" to stop the vultures from roosting in its radio towers.

For a radio tower and surrounding buildings operated by US Customs and Border Protection (CBP) near the Texas-Mexico border, vultures are no joke. Around 300 of the carnivorous birds have roosted in its radio tower, and are creating communications issues thanks to their corrosive vomit and feces.

Quartz reports that CBP filed a request for information that includes details about the problems the vultures have created at the radio tower, which is now entirely coated in "droppings mixed with urine" that have also fallen on the ground and surrounding buildings below, where people work and equipment is kept.

Furthermore, a CBP spokesperson told Quartz that workers have anecdotes of the vultures dropping prey from as high as 300 feet above, creating a "terrifying and dangerous" work environment for the past six years.
fernando sanchez/Shutterstock

Vultures regurgitate a corrosive vomit as a defense mechanism that can kill bacteria on their legs but also eat away at the metal radio tower, making it unsafe for maintenance workers to climb it and reducing the tower's lifespan.

Large groups of vultures also smell like corpses – the species is known, of course, for feeding on dead flesh, or carrion. Undigested bones and fur can be found at the base of where vultures roost.

But CBP can't kill the vultures, as the Migratory Bird Treaty Act made that illegal in 1918. Instead, the agency is searching for a "viable netting deterrent" to stop the vultures from roosting on the radio tower. CBP told Quartz that it's working with the Fish and Wildlife Agency, the USDA, environmental experts, and the Texas State Historical Preservation Officer to find a solution that doesn't harm any of the vultures.

The agency also says there are no nests or baby birds in the tower. There are plans to clean and repair the radio tower before installing nets by August, before the natural heavy roosting cycle begins in the fall. 



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Thursday, March 11, 2021

Wing tags severely impair flight in African Cape Vultures

Study urges the use of leg bands for marking individuals instead of wing tags

MAX-PLANCK-GESELLSCHAFT

Research News

IMAGE

IMAGE: CAPE VULTURE WITH PATAGIAL (WING) TAG FITTED CORRECTLY TO THE PATAGIUM view more 

CREDIT: VULPRO

Conservationists who apply wing tags for identifying Cape Vultures--a species of African vulture that is vulnerable to extinction--are putting the birds' lives further at risk, a new movement ecology study has shown. Researchers from the Max Planck Institute of Animal Behavior in Germany and VulPro NPC in South Africa have demonstrated that Cape Vultures fitted with tags on their wings travelled shorter distances and flew slower than those fitted with bands around their legs. The research emphasises the importance of investigating the effects that tagging methods can have on the behaviour and conservation of species, prompting a shift towards the less invasive method of leg bands in the future study of Cape Vultures.

For over a decade, many conservationists and NGOs have been marking vultures by placing a tag on the wing area known as the patagium. Patagial tags have the advantage that they are large and conspicuous enough for individuals to be identified from far away. Leg bands are smaller in size, fitted around the tarsus of the vultures leg and thus, harder to notice and record the unique number.

"After receiving many grounded and injured vultures from incorrect placement of wing tags, we felt there was an immediate need to find out exactly what these tags were doing to the flight of birds and whether this technique was, in fact, hindering the species rather than protecting them," says senior author Kerri Wolter, CEO of VulPro NPC, a vulture conservation organisation in South Africa.

The study was motivated by recent VulPro NPC research, which highlighted how an incorrect patagial tag could cause injuries and result in the grounding of vultures. To find out how patagial tags affected the birds' flights, researchers from the Max Planck Institute used GPS devices to track 27 Cape Vultures (Gyps coprotheres) marked with either patagial tags or leg bands.

The GPS devices, which were mounted to the birds' backs, recorded the birds' positions as often as every minute for 24 hours a day. These recordings allowed researchers to investigate the birds' flight performance, including occurrence of flight, proportion of time spent flying in a day, daily distance travelled and ground speed.

Individuals equipped with patagial tags covered a much smaller area in comparison to the leg band group. They were less likely to take flight and, when doing so, flew at lower ground speed compared to individuals wearing leg bands.

"Although we did not measure the effects of patagial tags on body condition or survival, our results strongly suggest that patagial tags have severe adverse effects on vultures' flight performance," says first author Teja Curk, a PhD student at the Max Planck Institute of Animal Behavior.

Vultures are scavengers. By feeding on dead animals, they play an important role in the ecosystem due to the services they provide, such as preventing the spread of infectious diseases, recycling organic material into nutrients and stabilising food webs.

"Therefore, restricted flight potential and a reduction in the area covered by these birds, caused by improper tag attachment, can have far-reaching consequences at the ecosystem level," says co-author Kamran Safi, a group leader at the Max Planck Institute of Animal Behavior.

###

Original publication Teja Curk, Martina Scacco, Kamran Safi, Martin Wikelski, Wolfgang Fiedler, Ryno Kemp and Kerri Wolter Wing tags severely impair movement in African Cape Vultures Animal Biotelemetry 9(11) 09 March 2021


CAPTION

Cape Vulture with a coloured leg band. By feeding on dead animals, vultures play an important role in the ecosystem due to the services they provide, such as preventing the spread of infectious diseases, recycling organic material into nutrients and stabilising food webs.

CREDIT

VulPro


Wednesday, November 20, 2024

 

Vultures and artificial intelligence(s) as death detectors: GAIA develops a high-tech approach for wildlife research and conservation





Leibniz Institute for Zoo and Wildlife Research (IZW)
AI data scientists and wildlife biologists at the Leibniz-IZW I3 lab 

image: 

AI data scientists and wildlife biologists analyse and interpret data from vulture tags and develop an Artificial Intelligence for behaviour recognition. The GAIA I³ Lab at the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) in Berlin brings together state of art expertise in Wildlife Biology and Artificial Intelligence development.

view more 

Credit: Photo by Jon A. Juarez




In order to use remote locations to record and assess the behaviour of wildlife and environmental conditions, the GAIA Initiative developed an artificial intelligence (AI) algorithm that reliably and automatically classifies behaviours of white-backed vultures using animal tag data. As scavengers, vultures always look for the next carcass. With the help of tagged animals and a second AI algorithm, the scientists can now automatically locate carcasses across vast landscapes. The algorithms described in a recently published article in the “Journal of Applied Ecology” are therefore key components of an early warning system that can be used to quickly and reliably recognise critical changes or incidents in the environment such as droughts, disease outbreaks or the illegal killing of wildlife.

The GAIA Initiative is an alliance of research institutes, conservation organisations and enterprises with the aim of creating a high-tech early warning system for environmental changes and critical ecological incidents. The new AI algorithms were developed by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) in cooperation with the Fraunhofer Institute for Integrated Circuits IIS and the Tierpark Berlin.

The death of wildlife is an important process in ecosystems – regardless whether this is a regular case, such as the successful hunt of a predator, or an exceptional case caused by the outbreak of a wildlife disease, the contamination of the landscape with environmental toxins or illegal killing by people. For the investigation of mammalian species communities and ecosystems it is therefore important to systematically record and analyse these regular and exceptional cases of mortality. In order to achieve this, the GAIA Initiative makes use of the natural abilities of white-backed vultures (Gyps africanus) in combination with highly developed biologging technologies and artificial intelligence. “This combination of three forms of intelligence ­– animal, human and artificial – is the core of our new I³ approach with which we aim to make use of the impressive knowledge that wildlife has about ecosystems”, says Dr Jörg Melzheimer, GAIA project head and scientist at the Leibniz-IZW.

Vultures are perfectly adapted by millions of years of evolution to detect carcasses across vast landscapes quickly and reliably. They have outstanding eye-vision and sophisticated communication that allows them to monitor very large areas of land when many individuals work together. Vultures thus fulfil an important ecological role by cleaning landscapes of carrion and containing the spread of wildlife diseases. “For us as wildlife conservation scientists, the knowledge and skills of vultures as sentinels are very helpful to be able to quickly recognise problematic exceptional cases of mortality and initiate appropriate responses”, says Dr Ortwin Aschenborn, GAIA project head alongside Melzheimer at the Leibniz-IZW. “In order to use vulture knowledge, we need an interface – and at GAIA, this interface is created by combining animal tags with artificial intelligence.”

The animal tags with which GAIA equipped white-backed vultures in Namibia record two groups of data. The GPS sensor provides the exact location of the tagged individual at a specific point in time. The so-called ACC sensor (ACC is short for acceleration) stores detailed movement profiles of the tag – and thus of the animal – along the three spatial axes at the exact same time. Both groups of data are used by the artificial intelligence algorithms developed at the Leibniz-IZW. “Every behaviour is represented by specific acceleration patterns and thus creates specific signatures in the ACC data of the sensors”, explains wildlife biologist and AI specialist Wanja Rast from the Leibniz-IZW. “In order to recognise these signatures and reliably assign them to specific behaviours, we trained an AI using reference data. These reference data come from two white-backed vultures that we fitted with tags at Tierpark Berlin and from 27 wild vultures fitted with tags in Namibia.” In addition to the ACC data from the tags, the scientists recorded data on the behaviour of the animals – in the zoo through video recordings and in the field by observing the animals after they had been tagged. “In this way, we obtained around 15,000 data points of ACC signatures ascribed to a verified, specific vulture behaviour. These included active flight, gliding, lying, feeding and standing. This data set enabled us to train a so-called support vector machine, an AI algorithm that assigns ACC data to specific behaviours with a high degree of reliability”, explains Rast.

In a second step, the scientists combined the behaviour thus classified with the GPS data from the tags. Using algorithms for spatial clustering, they identified locations where certain behaviours occurred more frequently. In this way, they obtained spatially and temporally finely resolved locations where vultures fed. “The GAIA field scientists and their partners in the field were able to verify more than 500 of suspected carcass locations derived from the sensor data, as well as more than 1300 clusters of other non-carcass behaviours”, says Aschenborn. The field-verified carcass locations ultimately served to establish vulture feeding site signatures in the scientists’ final AI training dataset – this algorithm indicates with high precision locations where an animal has most likely died and a carcass is on the ground. “We could predict carcass locations with an impressive 92 percent probability and so demonstrated that a system which combines vulture behaviour, animal tags and AI is very useful for large-scale monitoring of animal mortality”, says Aschenborn.

This AI-based behaviour classification, carcass detection and carcass localisation are key components of the GAIA early warning system for critical changes or incidents in the environment. “Until now, this methodological step has been carried out in the GAIA I³ data lab at the Leibniz-IZW in Berlin”, says Melzheimer. “But with the new generation of animal tags developed by our consortium, AI analyses are implemented directly on the tag. This will provide reliable information on whether and where an animal carcass is located without prior data transfer in real time without any loss of time.” The transfer of all GPS and ACC raw data is no longer necessary, allowing data communication with a significantly lower bandwidth to transmit the relevant information. This makes it possible to use a satellite connection instead of terrestrial GSM networks, which guarantees coverage even in remote wilderness regions completely independent of local infrastructure. Even at the most remote locations, critical changes or incidents in the environment – such as disease outbreaks, droughts or illegal killing of wildlife – could then be recognised without delay.

In recent decades, the populations of many vulture species declined sharply and are now acutely threatened with extinction. The main causes are the loss of habitat and food in landscapes shaped by humans as well as a high number of direct or indirect incidences of poisoning. The population of the white-backed vulture, for example, declined by around 90 percent in just three generations – equivalent to an average decline of 4 percent per year. “Owing to their ecological importance and rapid decline, it is essential to significantly improve our knowledge and understanding of vultures in order to protect them”, says Aschenborn. “Our research using AI-based analysis methods will not only provide us with insights into ecosystems. It will also increase our knowledge of how vultures communicate, interact and cooperate, forage for food, breed, rear their young and pass on knowledge from one generation to the next.” GAIA has so far fitted more than 130 vultures in different parts of Africa with tags, most of them in Namibia. Until today, the scientists analysed more than 95 million GPS data points and 13 billion ACC records.

White-backed vultures and a jackal at a carcass 

The development of the AI algorithms require a distinct multi-step process that includes data acquisition in the wild and from vultures under human care, data annotation and AI training. The new AI algorithms were developed by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) in cooperation with the Fraunhofer Institute for Integrated Circuits IIS and the Tierpark Berlin.

Credit

IIllustration by Clara C. Anders

Sunday, August 04, 2024

 

Turkey vultures fly faster to defy thin air


How large turkey vultures remain aloft in thin air



The Company of Biologists





Mountain hikes are invigorating. Crisp air and clear views can refresh the soul, but thin air presents an additional challenge for high-altitude birds. ‘All else being equal, bird wings produce less lift in low density air’, says Jonathan Rader from the University of North Carolina (UNC) at Chapel Hill, USA, making it more difficult to remain aloft. Yet this doesn’t seem to put them off. Bar-headed geese, cranes and bar-tailed godwits have recorded altitude records of 6000 m and more. So how do they manage to take to the air when thin air offers little lift? One possibility was that birds at high altitude simply fly faster, to compensate for the lower air density, but it wasn’t clear whether birds that naturally inhabit a wide range of altitudes, from sea level to the loftiest summits, might fine-tune their flight speed to compensate for thin air. ‘Turkey vultures are common through North America and inhabit an elevation range of more than 3000 m’, says Rader, so he and Ty Hedrick (UNC-Chapel Hill) decided to find out whether turkey vultures (Cathartes aura) residing at different elevations fly at different speeds depending on their altitude. They publish their discovery in Journal of Experimental Biology that turkey vultures fly faster at altitude to compensate for the lack of lift caused by flying in thin air.

First the duo needed to select locations over several thousand meters’ altitude, so they started filming the vultures flying at the local Orange County refuse site (80 m above sea level); ‘Vultures on a landfill… who would have guessed?’, chuckles Rader. Then they relocated to Rader’s home state of Wyoming, visiting Alcova (1600 m) before ending up at the University of Wyoming campus in Laramie (2200 m). At each location, the duo set up three synchronized cameras with a clear view to a tree that was home to a roosting colony of turkey vultures, ready to film the vultures’ flights in 3D as they flew home at the end of the day. ‘Wyoming is a famously windy place and prone to afternoon thunderstorms’, Rader explains, recalling being chased off the roof of the University of Wyoming Biological Sciences Building by storms and the wind blurring movies of the flying birds as it rattled the cameras.

Back in North Carolina, Rader reconstructed 2458 bird flights from the movies, calculating their flight speed before converting to airspeed, which ranged from 8.7 to 13.24m/s. He also calculated the air density at each location, based on local air pressure readings, recording a 27% change from 0.89kg/m3 at Laramie to 1.227 kg/m3 at Chapel Hill. After plotting the air densities at the time of flight against the birds’ airspeeds on a graph, Rader and Hedrick could see that the birds flying at 2200m in Laramie were generally flying ~1m/s faster than the birds in Chapel Hill. Turkey vultures fly faster at higher altitudes to remain aloft. But how do they achieve these higher airspeeds?

Rader returned to the flight movies, looking for the tell-tale up-and-down motion that would indicate when they were flapping. However, when he compared how much each bird was flapping with the different air densities, the high-altitude vultures were flapping no more than the birds nearer to sea level, so they weren’t changing their wingbeats to counteract the effects of low air density. Instead, it is likely that the 2200 m high birds were flying faster simply because there is less drag in thin air to slow them down, allowing the Laramie vultures to fly faster than the Chapel Hill birds to compensate for generating less lift in lower air density.

 

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REFERENCE: Rader, J. A. and Hedrick, T. L. (2024). Turkey vultures tune their airspeed to changing air density. J. Exp. Biol. 227, jeb246828. doi:10.1242/jeb.246828

DOI: 10.1242/jeb.246828

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