Scientists Have Been Studying Fire Salamanders for More Than 250 Years. They Just Discovered That the Creatures Glow Under UV Light
Fire salamanders—one of Europe’s most well-researched amphibians—are biofluorescent, which means they can absorb light from an external source at one wavelength, then re-emit it at another
Fire salamanders are among the most-studied amphibians in Europe, yet until now, no one realized they are biofluorescent. Bernat Burriel-Carranza
First described more than 250 years ago, fire salamanders are among the most-studied amphibians in Europe. Yet researchers are still making new discoveries about these charismatic creatures. Most recently, scientists learned that fire salamanders emit a bluish-green glow after being exposed to ultraviolet light, wavelengths that humans usually can’t see.
It’s the first time the phenomenon, known as biofluorescence, has been documented in the species, researchers report in a study published May 27 in the journal Royal Society Open Science. Though the ecological functions of biofluorescence remain unclear, scientists suspect that the amphibians might use the glow to communicate with one another, select mates or ward off predators.
Biofluorescence occurs when organisms absorb light from an external source at one wavelength, then re-emit it at another. Scientists used to think that only marine creatures and arthropods—a group that includes insects and arachnids—were biofluorescent. But in recent decades, they’ve been finding the trait in more animals, including some reptiles, birds and amphibians.
The bright, sparkly pattern is concentrated in the yellow spots on the creatures’ skin. Bernat Burriel-Carranza
“We are in a thrilling period of discovery in terms of biofluorescence in amphibians and other [four-limbed vertebrates],” Jennifer Lamb, a biologist at St. Cloud State University who was not involved with the research, tells National Geographic’s Jack Tamisiea.
Studies like this one, she adds, “help fill some of the gaps in our understanding, both in terms of what species fluoresce and in terms of the mechanisms likely responsible for that fluorescence.”
Against this backdrop, Bernat Burriel-Carranza, an evolutionary biologist at the Natural Sciences Museum of Barcelona, decided to start taking an ultraviolet (UV) flashlight, also known as a blacklight, with him on evening field expeditions. On a rainy night in Spain, he spotted a fire salamander crossing the road and pointed the beam at it. The flashlight revealed a bright, speckled pattern along the creature’s flanks.
Did you know? Biofluorescence vs. bioluminescence
Biofluorescent animals require an external light source to glow, while bioluminescent creatures produce their own light through chemical reactions in their cells.
Common throughout Europe, fire salamanders are small, black-and-yellow amphibians that range from 6 to 12 inches long. These nocturnal critters tend to live in cool, damp forests near bodies of water, where they feast on worms, slugs and other insects. If they feel threatened, fire salamanders can protect themselves via toxins in their skin or by spraying poisonous liquid from glands behind their eyes. They breathe through their skin, can regrow their limbs and tails and give birth to live young.
After the initial field observation in Spain, Burriel-Carranza and his colleagues decided to investigate biofluorescence in fire salamanders further. Between April 2024 and November 2025, they searched for fire salamanders in Spain and Germany, illuminated them with a UV flashlight and took photographs to capture the bright, speckled glow. The fluorescence seemed to be coming mostly from the yellow spots on the creatures’ skin and concentrated along their sides and stomachs.
Scientists think the yellow splotches might serve as warning signs to potential predators. Andrés Brunetti
Researchers also swabbed the salamanders’ skin to collect samples of their toxic secretions. When they exposed the slime to UV light, it glowed, too, suggesting the biofluorescence may be coming from the glands that produce the poisonous goo.
CW: animal cruelty
To confirm that hypothesis, the team dissected two preserved fire salamanders. When they looked at tissue samples under a microscope, they found fluorescent chemical compounds in the glands and bloodstream, which suggests the substances circulate throughout the creatures’ bodies. That’s something that had previously been observed only in some tree frogs, which use fluorescent compounds known as hyloins to illuminate their translucent skin.
Researchers suspect that the biofluorescence plays a role in communication. Bernat Burriel-Carranza
“We still don’t know what the compound responsible for this fluorescence is, but everything indicates that it is a molecule unknown until now in this species,” says study co-author Salvador Carranza, a biologist at the Institute of Evolutionary Biology in Spain, in a statement. “Identifying it will be key to understanding its origin and function.”
Though humans usually need a UV light to see the salamanders’ blue-green glow, it might be more clearly visible to other animals. Because salamanders are nocturnal and live in dense forests, one possible explanation is that they fluoresce so they can see one another better at night. The researchers say this proposal is supported by the fact that, compared with daylight, full moonlight contains more UV and violet wavelengths, the ones that are absorbed by the animals and re-emitted at different wavelengths. Additionally, the amount of moonlight that reaches the forest floor peaks in the fall, when the salamanders usually breed.
The toxic secretions that fire salamanders produce from their skin also glow under UV light, the researchers discovered. Bernat Burriel-Carranza
Beyond flagging down potential mates, the amphibians might also be using their natural fluorescence as a warning to predators. The scientists think the creatures use their bright yellow splotches as natural “keep away” signs, and because the fluorescence is concentrated in those markings and their toxic secretions, it may help reinforce that warning.
No matter how fire salamanders use their biofluorescence, Burriel-Carranza finds it “fascinating” that such a well-studied species could still hold undiscovered traits, he says in the statement.
“It reminds us that even the most familiar organisms can hide secrets that are only revealed when they are observed with new tools,” he adds.
Banner image: Turquoise dwarf gecko. Image © Ardgard Essau via iNaturalist (CC BY-NC 4.0).
How trade bans and local conservation helped save a dazzling blue gecko
Beauty is a curse — at least for the turquoise dwarf gecko of central Tanzania. Between December 2004 and July 2009, demand for this gecko from collectors in Europe boomed, leading to the capture and export of an estimated 40,000 of these striking reptiles from Tanzania.
“I remember when I saw them for the first time [at] a fair, it was about 600 euros per specimen,” or about $700, Dennis Rödder, a herpetologist at the Leibniz Institute for the Analysis of Biodiversity Change in Germany, told Mongabay in a video call. “I think within three or four years, the species appeared everywhere across Europe. You could buy them in every pet shop.”
Turquoise dwarf geckos (Lygodactylus williamsi) grow to a length of 6-9 centimeters (about 2.5-3.5 inches) and are known from only two small patches of forest in Tanzania: The Kimboza and Ruvu forest reserves. These protected areas cover a combined 34 square kilometers (13 square miles). Adult females have a green-brownish color that mimics the leaves of the trees they live in, but the males’ skins are a vivid contrasting blue, one of the rarest colors in nature, meant to stand out and attract females.
Turquoise dwarf gecko (Lygodactylus williamsi). Image © Simon via iNaturalist (CC BY-NC 4.0).
Active during the day, and so fiercely territorial they evict their young hatchlings from their home trees soon after birth, this species lives exclusively on screwpines (Pandanus rabaiensis), a tree found in Kenya and Tanzania. Standing anywhere from 3-20 meters tall (up to 66 feet), these trees feature long, spiked leaves and a fountain-shaped architecture that provide the ideal habitat for the reptiles, giving them shelter to hide and reproduce, a platform to bask, and a feeding place where water for cooling and insects accumulate.
“It’s the perfect environment for them,” Charles Kilawe, a forest ecologist at Tanzania’s Sokoine University of Agriculture, told Mongabay in a video call. “The leaves of the Pandanus have spines, and it protects [the lizards] against predators like snakes or … eagles.”
But the gecko’s reliance on the screwpine as protection against natural predators has left it vulnerable to another predator: using machetes, poachers cut down large screwpines to grab their helpless resident geckos. The logging to capture these animals was so intense that by 2009, screwpines had gone from covering more than half of Kimboza to only 17.6% of the forest reserve’s area.
That year, researchers estimated that only around 150,000 of these beautiful geckos remained in the wild.
“When I started to work there in 2016, it was difficult to spot them,” Kilawe said.
In 2009, herpetologist Morris Flecks and colleagues from the Leibniz Institute interviewed one group of gecko collectors from the communities around Kimboza and estimated that they had captured between 32,000 and 42,000 turquoise dwarf geckos from the forest reserve over the previous five years. The researchers noted that this total — which they believed represented at least 15% of the wild population at the time — could be even higher as it didn’t account for many more geckos collected by other groups known to be operating in the forest.
Collection or export of the geckos — or any other wildlife species from a protected forest reserve — required a license, but officials from the Tanzania Wildlife Research Institute told the researchers no such permits were ever issued.
This frenzied collection for the pet trade and the rapid destruction of their already limited habitat led to a steep decline in the geckos’ population size; Rödder, Flecks and other herpetologists recommended that the species should be listed as critically endangered by the IUCN. This was done in 2012. It took another five years before international trade in turquoise dwarf geckos was banned when the species was added to Appendix I of CITES, the global treaty on the wildlife trade.
By this time, the wholesale capture of the geckos in the shadow of Tanzania’s Uluguru Mountains had tapered off; overseas markets were saturated, and while the reptiles remained popular, captive-bred geckos were widely available across Europe, pushing the price of a turquoise dwarf gecko from a peak of $1,500 per specimen to just $40 each.
“Population sizes are back to pre-collecting events. So that’s the good part,” Rödder told Mongabay.
“The not-so-good part is that after a couple of years after our study, there was a wildfire in one of these reserves.”
The white-chested alethe (Chamaetylas fuelleborni) is one of several species that have returned to Kimboza, thanks to restoration efforts involving members of the local community. Image © Zein et Carlo via iNaturalist (CC BY-NC 4.0).
Habitat loss due to illegal logging, collection of firewood, conversion of forest to agricultural land, mining, and the growing presence of the invasive Spanish cedar (Cedrela odorata) inside and outside the two forest reserves where L. williamsi is found continue to put pressure on the geckos.
Spanish cedar was introduced to Kimboza in 1960, ironically as a means to relieve logging pressure on native tree species. The idea was that this fast-growing tree, native to the Americas, could provide a reliable source of quality timber and firewood.
The idea was too successful. The exotic cedar, which can grow to a towering 40 m (130 ft), turned out to be very invasive: because it produces seeds twice a year that are dispersed by wind and germinate easily in open areas, the species has taken advantage of gaps and changes to forest structure caused by illegal logging and fires to replace screwpine in many areas.
“By 2016, Cedrela was the most dominant tree in the forest, covering nearly 32% of the big trees area,” Kilawe told Mongabay.
In 2022, Kilawe published a study of Kimboza aimed at determining if turquoise dwarf geckos were directly affected by the presence of Spanish cedars. He found screwpines still thriving in swampy areas and on limestone outcrops, but where a similar survey 40 years earlier found P. rabaiensis in more than half of plots it surveyed, screwpines occurred in barely half the plots Kilawe examined — a severe reduction in habitat for geckos. The presence of cedars, meanwhile, had moved in the opposite direction, found in 16% of plots in 1982, but 52% in Kilawe’s study.
While he found turquoise dwarf geckos just as frequently in screwpines growing under the taller cedars, results from the surveyed plots showed that the number of lizards in screwpines shadowed by dense exotic canopy was considerably lower than in areas where there were fewer cedars or none at all.
Further research is needed to understand what the direct effect of the cedars’ presence on geckos is, but the invasives’ steady expansion into forest areas opened up by fire or tree falls raises fears that cedars will continue to displace gecko habitat. Similar impacts on native biodiversity have been reported from other places where the tree has been introduced, such as Ghana and the Galápagos Islands.
Screwpine (Pandanus rabaiensis) in Morogoro, Tanzania. Image © Andrey Vlasenko via iNaturalist (CC BY-NC 4.0).
Today, people from the villages surrounding Kimboza Forest Reserve assist rangers in managing the forest, Kilawe said. Led by Kilawe, they have cut down nearly 100,000 Spanish cedar trees since 2016, and reduced forest fires by around 80%.
They have also planted about 5,000 native trees per year since 2018, working step by step to rebuild the original structure of Kimboza’s forest. Kilawe told Mongabay 10 “ambassadors” drawn from the different villages are paid for their efforts; guiding tourists is another source of occasional income linked to protecting this ecosystem.
“We are hoping that if the removal process continues, in about five years, maybe the forest might be Cedrela-free,” Kilawe said. “It is very important and effective to work with the community in conservation.”
Once caught between the devil and the blue sea, the turquoise dwarf gecko is recovering thanks to these reforestation efforts and the prohibition on trade worldwide. Kilawe said the restoration of Kimboza’s forests has also allowed other animals, such as blue monkeys (Cercopithecus mitis) and birds like the white-chested alethe (Chamaetylas fuelleborni) and the trumpeter hornbill (Bycanistes bucinator) to return to the forest, showing that collaborative hard work can save species and places from the fragile edge of extinction.
Hidden in plain sight: the race to discover new species before they’re gone
When most people imagine scientists discovering new species, they probably still picture an expedition into the unknown.
A naturalist travels somewhere remote, perhaps on a wooden ship, and traipses through the jungle to encounter an animal or plant never before described by science. The intrepid explorer brings back specimens or observations to a museum, where they can be compared, named and described.
There is some truth to this stereotype. Between 1854 and 1862, scientist Alfred Russel Wallace travelled through the Malay Archipelago, discovering animals and insects unknown to Western science. This led him to the theory of evolution by natural selection, contemporaneously with Charles Darwin.
Antarctica had its own era of discovery. In 1840, scientists on a French expedition encountered what we now know as Adélie penguins. Imagine seeing penguins for the first time: strange black-and-white birds waddling over the ice, sliding on their bellies, leaping from freezing seas.
Of course, “discovery” is a loaded word. Many animals and plants described by Western science were already known to Indigenous peoples and local communities. What changed was their entry into the formal scientific naming system – the global process by which species are compared, classified and recognised.
Today, scientists are still finding new life in remote places and hidden inside the DNA of animals we thought we already knew.
We still explore unknown worlds
Scientists still discover species this way: by probing Earth’s nooks and crannies and travelling to remote places to study what lives there.
Last year, I was onboard the scientific vessel R/V Falkor (too) in Antarctica’s Weddell Sea, where one scientific team was searching for seafloor methane seeps.
These are not just geological curiosities. Methane seeps create unusual habitats that harbour strange communities of life fuelled not by sunlight, but by chemicals rising from below. Scientists have already found new microbial diversity at Antarctica’s first known active methane seep.
Not all hard-to-reach worlds are underwater. In Papua New Guinea’s Southern Fold Mountains, camera traps captured a shy, ground-dwelling bird slipping through rugged limestone forest. Scientists described it as a new species in 2025, the hooded jewel-babbler.
But there is another kind of discovery happening too.
White microbial mats underwater are telltale signs of seeping methane. Andrew Thurber, CC BY-ND
Hidden species in familiar animals
Some species are not hidden because they live at the bottom of the sea or deep in a mountain forest. They are hiding in plain sight.
Gentoo penguins are a good example. With their bright orange bills and comic waddle, they are familiar to anyone who has visited Antarctica. To most observers, they are simply “gentoos”.
But our new research shows gentoo penguins are not one widespread species, but four. Our 2020 study first showed major genetic and physical differences between gentoo penguins from different islands.
Now, using whole genomes – the complete set of genetic instructions inside an animal – and ecological modelling, we found these penguins are not just separated by distance, but have adapted to different Southern Ocean worlds.
Gentoo penguins on Cuverville Island, Antarctica. David Stanley/flickr, CC BY-ND
Learning to see in higher resolution
Discoveries like this are often called “hidden” species. They look very similar to their relatives, but if we study their DNA, body measurements, behaviour and ecology, it’s clear they are separate species.
Species discovery has always depended on the tools available. Early naturalists relied on what they could collect: feathers, skins, eggs and bones. These museum collections are like time machines and remain incredibly important.
Today, whole genomes tell us if animals have different coding. Ecological models show whether animals live in different environmental conditions. Mathematical approaches test whether groups are evolving independently.
In other words, we are learning to see biodiversity in higher resolution.
This sharper view is changing how we understand familiar animals. For a long time, giraffes were considered one species, but genetics suggests they are four. My own work on forest birds in Madagascar found a new species of Newtonia bird.
The Tapanuli orangutan is a powerful example. This Indonesian great ape from Sumatra was described as a new species in 2017, based on genomic, anatomical and behavioural evidence. It was extraordinary to recognise a new great ape in the 21st century, and sobering to realise fewer than 800 may remain.
Again and again, the message is the same. The natural world is more complex than we know. And sometimes, by the time we recognise that complexity, a species may already be in deep trouble.
The Tapanuli orangutan is a species of orangutan restricted to South Tapanuli in the island of Sumatra in Indonesia. It is one of three known living species of orangutan. Prayugo Utomo/Creative Commons, CC BY
Why names matter
Taxonomy – the science of naming and classifying life – can sound like an old-fashioned labelling exercise. But it’s how we map life on Earth.
Conservation laws, threatened species lists and monitoring programs usually work at the species level. If several species are mistakenly treated as one, a declining species can be hidden inside a larger group that looks secure.
As we stand at the precipice of Earth’s sixth mass extinction, this has never been more important.
Recognising hidden biodiversity does not solve conservation problems by itself. But it helps us ask better questions. Which species are increasing? Which are declining? Which have not been counted for decades?
These questions are urgent, because we are racing to understand biodiversity while climate change and habitat loss reshape life on Earth.
Even now, in an age of satellites and genome sequencing, Earth still has secrets. Not only in the most remote places, but in the first animals we learn to recognise as children: penguins, giraffes, orangutans.
The closer we look, the more life reveals itself. Our task now is to keep looking and protect the richness that was there all along.
Cover image:
Two individuals of Thecacera sesama sp. nov. feeding on a bryozoan. Image credit: Ho-Yeung Chan et al.
Tiny sesame sea slug species discovered in the waters of northern Taiwan | Blog
This tiny nudibranch, which measures less than three millimetres in length, was first spotted by lead author Ho-Yeung Chan during a recreational dive in 2019.
Translucent, speckled, and barely the size of a grain of rice, a new species of sea slug has been identified in the coastal waters of Keelung, Taiwan. Because of its minute size and distinctive black and yellow markings, researchers from National Taiwan Ocean University, National Museum of Natural Science and National Taipei University of Education have named the creature Thecacera sesama.
“Taiwanese divers call it ‘sesame’ in Chinese and it is also small like a sesame seed, hence the name,” the research team explained regarding their decision to honour the local nickname in the scientific nomenclature. This tiny nudibranch, which measures less than three millimetres in length, was first spotted by lead author Ho-Yeung Chan during a recreational dive in 2019.
Thecacera sesama sp. nov. Details of appearance and morphological features, hand-drawn on a tablet PC by Chen-Lu Lee.
The discovery was a stroke of luck that began during Chan’s undergraduate studies:
“During a recreational dive in the summer during the undergraduate study of HY Chan in 2019, he accidentally discovered Thecacera sesama sp. nov. in northern Taiwan waters.”
The Research Team
Despite its unique appearance, the importance of the find was not immediately obvious. In a modern twist on traditional taxonomy, Chan “never realised Thecacera sesama was a new species until he consulted the sea slug expert ‘Hsini Lin teacher’ on Facebook.”
Living specimens of Thecacera sesama sp. nov. Image credit: Ho-Yeung Chan et al.
Documenting the species proved to be a significant logistical feat due to the volatile environment of the Keelung coast. The research team noted that the most challenging part of the study was the unique weather conditions of the region.
Taiwan experiences frequent typhoons in the summer and large waves during the winter monsoon season, with sea temperatures often dropping below 16 degrees Celsius. These factors mean that diving for nudibranch research is only possible for about four months of the year, making sightings of such tiny creatures entirely a matter of chance.
Living specimens of bryozoan with Thecacera species. Image credit: Ho-Yeung Chan et al.
The life of T. sesama is remarkably focused, as the researchers observed that the species exhibits only four primary behaviours: feeding, searching, mating, and laying eggs on bryozoans, which are tiny aquatic invertebrates often called “moss animals”. Interestingly, the specific bryozoan that T. sesama calls home may itself be a species new to science.
From a broader ecological perspective, these vibrant molluscs play a vital role in the marine environment:
“Nudibranchs are one of the key players in the marine food web. They are extremely colourful and can be spotted on coral reef ecosystems. However, many nudibranchs are very small in size and are extremely difficult to spot underwater with the naked eye.”
The Research Team
The researchers believe that the discovery of T. sesama is just the tip of the iceberg for Taiwanese marine biology. Because many species are so small, many more are likely awaiting discovery and formal study. The full research on Thecacera sesama was published in the open-access journal ZooKeys on 11 May 2026.
Original source:
Chan H-Y, Lee C-L, Chen W-C, Chang C-H, Shao Y-T, Pang K-L (2026) Thecacera sesama sp. nov. (Nudibranchia, Polyceridae) from Taiwan, evident from morphology and phylogenetic analyses of the 16S rDNA and cytochrome c oxidase I gene. ZooKeys 1279: 269-284. https://doi.org/10.3897/zookeys.1279.184298
'Lethally salty' waters hinder rare toad's recovery
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The study found toad survival and size was affected by the salt levels in the water
Salty water could be preventing the recovery of one of the UK's rarest amphibians by making former breeding sites unsuitable for their survival, a study has concluded.
The natterjack toad is found in just a handful of locations.
In Scotland, its only remaining homes are along the Solway Coast, including the RSPB's Mersehead Reserve near Southerness.
Scientists have found that the salt level in water from former breeding sites in south-west Scotland was linked to failed hatching, smaller growth and altered development.
The research is published in the academic journal Ichthyology and Herpetology.
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The study took samples at various sites to check their salt levels
The project was led by Dr Frances Orton, an environmental biologist at Edinburgh's Heriot-Watt University.
"Natterjack toads have declined across the UK, not just in Scotland," she said.
"We wanted to find out why these tiny toads were surviving in the nature reserve in Dumfries and Galloway, but had disappeared from sites along that coast.
"We used anecdotal reports from farmers and local wildlife groups to identify former breeding ponds in Caerlaverock, Southerness and several farms."
The team analysed water samples from Mersehead, where the natterjack toad survives, and other sites.
They measured temperature, pH and salinity and exposed natterjack spawn to water from each of the sites.
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Scotland's only remaining natterjack toad colonies are along the Solway Coast
Orton said: "Some of the former breeding sites had such a high level of salinity that no embryos survived to hatching.
"Some weren't as lethally salty, but what we saw there was that the toads were much smaller.
"That doesn't sound like a big deal, but when you're a frog, size really does matter. 95% of tadpoles are eaten by predators.
"For the 5% that make it to the next stage of development, they need to be as big as possible for a chance at survival."
She said the findings could help improve work to revive numbers.
"Until now, a lot of natterjack toad restoration efforts have focused on improving terrestrial habitat, like clearing scrub or controlling vegetation," she said.
"That's still important, but now we know that unless the salinity of the water is tackled, the tiny toads will have no chance of survival."
The biologist added that action needed to be taken soon.
"Amphibians are the fastest-declining vertebrate group globally," she said.
"They've been around for 350 million years, but now species like the natterjack toad are disappearing, quickly.
"They play a huge ecological role as both predators and prey - they feed lots of animal species and, as gardeners will tell you, they eat lots of slugs and midges.
"Natterjack toads are on the verge of extinction and it's vital we understand ways to protect and boost the populations that remain."
Orton and her team conducted the research - supported by the Carnegie Trust and NatureScot - across seven sites in Dumfries and Galloway.
How homing pigeons keep navigation simple when winging their way home together
Credit: Altaf Shah from Pexels
When it comes to flocking together, homing pigeons use a simple strategy to find better ways home, according to a recent report. The study, published in the journal eLife, suggests that homing pigeons use simple route averaging when navigating as a group. eLife's editors say the work addresses an important question, and provides compelling evidence based on multiple models and data on how homing pigeons can generate social routes from solitary ones.
The findings open avenues for future research to investigate the evolution of the mechanisms used by homing pigeons and other social animals when deciding on the best route to travel.
How pigeons pick their routes
How animals navigate complex environments depends on their cognitive abilities. When traveling in groups, some animals pool individual information to improve their navigation. This can be achieved by following experienced leaders, which requires recognizing the experts of the group, or by using simpler mechanisms, such as the "wisdom of crowds" principle, which averages the routes of all individuals. These strategies therefore range from cognitively complex to simple, but their prevalence or interplay in nature remains unexplored.
"This is where the homing pigeon comes in: as a social species that has been studied extensively for their ability to develop and recall routes, these birds are an ideal model organism for studying navigational strategies," says author Shoubhik Banerjee, a Ph.D. student in senior author Albert Kao's lab at the University of Massachusetts Boston (UMass Boston), US. Banerjee and Kao conducted the study with Postdoctoral Researcher Fritz Francisco, also a member of the Kao Lab.
A previous study published in 2017 showed that pairs of experienced and naïve homing pigeons could continuously improve their homing routes over the course of the experiment. The study proposed the key driver to be cumulative cultural evolution (CCE), where chains of birds improve their routes by exploring different options and choosing better ones. However, a detailed mechanistic understanding of how these route improvements emerge is still lacking.
"Building on that study, we aimed to investigate the mechanisms that pigeons use to improve their route efficiency and whether those mechanisms fall under the criteria required for CCE," Banerjee adds.
Inside the experimental design
The previous work involved creating "chains" of birds, similar to a game of telephone, and allowing them to fly back home repeatedly from a release site 8.4km away. Each chain was composed of five "generations" and included an experienced bird that knew about the homing task from the previous generation, paired with a naïve bird that lacked this information.
At the end of the generation (12 flights), the experienced pigeon was replaced with a new, naïve pigeon that traveled with the remaining, now-experienced bird. Working as control groups, solo and fixed pairs of birds carried out the same number of flights as the experimental group (a total of 60 flights). The study found that the experimental chains of birds significantly outperformed both the solo and fixed pair controls by the end of the fifth generation—a result attributed to CCE.
Illustration of the hypothesized social learning strategies. Credit: eLife (2026). DOI: 10.7554/elife.108054.3
Testing different learning strategies
Banerjee, Francisco and Kao set out to explore which navigation mechanism is necessary and sufficient to replicate those experimental results. They developed seven plausible learning mechanisms, categorized into three types with increasing cognitive complexity.
The first type represents the simplest process, where birds have no knowledge of their partner's level of experience or performance, and includes only the averaging strategy. The second type assumes that birds can recognize the more experienced individual in the pair and maximize their performance using this knowledge. And the third type introduces the highest level of cognitive complexity, which requires birds to actively evaluate their individual or paired performance, aligning with the mechanistic criteria required for CCE.
The team then compared the results of the seven mechanisms with the experimental data to identify which strategies are most likely to be used by real birds. In particular, they explored whether the cognitive requirements of CCE are necessary for the observed improvement in navigation ability.
Simple averaging comes out on top
They found that all of the strategies resulted in route improvements, regardless of their underlying complexity, which suggests that a wide range of decision-making mechanisms can lead to navigational improvements—not just the ones compatible with the definition of CCE. However, when they combined the results with those from a social weight analysis, they found that the experimental data aligned best overall with the simplest strategy: averaging individual routes.
"We show that an improvement in route efficiency alone is not sufficient evidence for cultural transmission, as the experimental birds did not demonstrate some of the criteria of CCE," says author Fritz Francisco. "This could be due to the wisdom of crowds improving routes 'for free' without placing additional cognitive load on the birds. On average, birds in this experiment influenced each other's routes equally, disregarding any differences in experience, which raises broader questions about which social learning mechanisms truly align with the requirements for CCE."
What this means for future research
The team further observed that mixed strategies, while not supported by the experimental data, theoretically combined advantages from both averaging and active selection of better routes, resulting in even greater performance.
"Our results therefore pave the way for future studies to investigate the evolution of social learning and trade-offs among the different decision mechanisms that may be available to animals in the wild," concludes senior author Albert Kao, Assistant Professor and Principal Investigator at UMass Boston.
"For this navigation task, simple averaging is sufficient to explain the experimental results in homing pigeons, but other tasks may be less amenable to the wisdom of crowds—there's a lot of complexity in this area. It would be interesting to explore how collective navigation strategies evolve in different contexts, taking into account, for example, typical group sizes, error rates, and how many times a task is repeated, to better understand social decision-making in homing pigeons and other animals."
Study clarifies conditions for amphibian species richness on marine islands
Ecology
Study clarifies conditions for amphibian species richness on marine islands
Analysis of data from over 5,000 territories and 1,924 species of toads and frogs shows that two of the main theories about the biodiversity of plants, birds, and mammals in these habitats do not explain the richness of anuran amphibians on their own.
Ecology
Study clarifies conditions for amphibian species richness on marine islands
Analysis of data from over 5,000 territories and 1,924 species of toads and frogs shows that two of the main theories about the biodiversity of plants, birds, and mammals in these habitats do not explain the richness of anuran amphibians on their own.
The Brazilian white-edged tree frog (Boana albomarginata) lives on the mainland and on islands, but the island populations are much larger than the mainland populations (photo: Raoni Rebouças/IB-UNICAMP)
By André Julião | Agência FAPESP – A Brazilian study published in the journal Ecography indicates that the biodiversity of anuran amphibians (toads and frogs) on islands is determined by factors encompassed in two previously opposing theories.
“Biodiversity models that consider island size, distance from the mainland, and productivity [of organic matter per area] have been confirmed with relative success for plants, birds, and mammals, but they hadn’t yet been tested with anuran amphibians, which can’t tolerate salinity and therefore face an insurmountable barrier in the sea,” says Raoni Rebouças, first author of the study, which he conducted as part of his postdoctoral research at the Institute of Biology of the State University of Campinas (IB-UNICAMP) with a fellowship from FAPESP.
To verify whether the models applied to anuran amphibians, the researchers compiled data from over 5,000 marine islands worldwide. Size, distance from the mainland, and climate were among the factors taken into account. The database also included information on the ecological characteristics of 1,924 anuran amphibian species found on marine islands.
The researchers analyzed the number of species on each island, as well as other measures of diversity. These include functional or ecological niche diversity, which considers whether a species is terrestrial, aquatic, arboreal, or fossorial (meaning it lives underground), and phylogenetic diversity, which measures how many evolutionary lineages exist in the area.
“If there are 200 species on an island, but they all belong to the same family and are all aquatic, then there’s high species richness, but low phylogenetic and functional diversity,” explains Matheus Moroti, co-author of the article and a postdoctoral researcher at IB-UNICAMP funded by FAPESP.
In addition to the global analysis, which included all islands and species, the researchers analyzed the biodiversity of anuran amphibians according to climate, distinguishing between tropical and temperate regions.
“Our results show that distance from the mainland, size, and productivity are important for explaining the diversity of anuran amphibians on islands, but their relevance differs depending on the climate [tropical or temperate] and the diversity being considered – whether it’s species richness, functional diversity, or phylogenetic diversity,” says Moroti.
Mantella baroni is one of more than 300 species of anuran amphibians in Madagascar, a large island off the southeast coast of Africa (photo: Leslie Poulson/Creative Commons license via Raoni Rebouças)Complementary theories
According to the theory of island biogeographic equilibrium, developed based on two papers by Robert MacArthur and Edward O. Wilson, one from 1963 and the other from 1967, the larger the island and the shorter the distance to the mainland, the greater the species richness. This is because species can easily migrate between islands, and larger islands have more space to support many individuals.
On small islands far from the mainland, migration rates would be lower and extinction rates higher, resulting in lower diversity. Subsequently, the theory was tested and confirmed for various groups.
“But for those that can’t tolerate salt, any marine island is distant. That’s why we had to test this theory with anuran amphibians,” recalls Rebouças.
Another important theory regarding island biodiversity considers a factor overlooked by MacArthur and Wilson: the amount of energy available for species to live and evolve on an island, regardless of its size.
Proposed by David Wright in 1983, the species-energy theory suggests that the availability of energy in the form of organic matter productivity per area alone determines diversity on islands.
: Islands seen from Ubatuba, on the coast of the state of São Paulo. Island environments influence amphibian biodiversity differently than they do other animals and plants (photo: Raoni Rebouças/IB-UNICAMP)Thus, islands of the same size can have different species richness depending on their productivity. The greater the energy produced, the greater the capacity to support a large number of individuals.
“A good example is the world’s largest island, Greenland. Covered in ice for much of the year, it has no frog species. Meanwhile, the second-largest, Borneo, has over 400,” Rebouças explains.
After cross-referencing the available data, the researchers concluded that neither theory alone explains the diversity of anuran amphibians on islands. Rather, both theories are complementary, each providing a better explanation depending on the type of biodiversity measured (species, functional, or phylogenetic) and the climate regime (tropical or temperate).
For example, when considering species and lineage richness, global and tropical data point to a strong correlation with island size. However, in temperate regions, this relationship is weak, as seen in Greenland.
Functional diversity, or the diversity of ecological niches such as terrestrial, aquatic, arboreal, and fossorial, is closely linked to climate when considering the entire world and temperate regions. However, the relationship is weak in tropical regions, which do not depend as much on climate for different niches.
Future studies should examine historical factors influencing diversity on islands. Additionally, a finer-grained analysis could be conducted that includes river islands and considers the extent of water bodies present on the islands.
This study received support from FAPESP through three projects (16/25358-3, 19/18335-5, and 20/12658-4). Two of these projects were part of the Research Program on Biodiversity Characterization, Conservation, and Sustainable Use (BIOTA-FAPESP).
The article “Environmental and geomorphological drivers of frog diversity on islands worldwide” can be read at nsojournals.onlinelibrary.wiley.com/doi/10.1002/ecog.07818.
^The\ Puerto\ Rican\ crested\ toad\ is\ the\ only\ toad\ native\ to\ Puerto\ Rico\ and\ was\ once\ thought\ to\ be\ extinct\ in\ the\ wild.\ Today,\ the\ species\ persists\ through\ one\ of\ the\ world's\ longest-running\ amphibian\ reintroduction\ efforts\ but\ remains\ listed\ as\ endangered\ by\ the\ International\ Union\ for\ Conservation\ of\ Nature\ (IUCN).\ Credit:\ Brookfield\ Zoo\ Chicago^
Behind the scenes at Brookfield Zoo Chicago, a record-breaking conservation milestone is helping secure the future of one of the world's most imperiled amphibians. Months of meticulous care and coordination enabled Brookfield Zoo Chicago to successfully breed and raise 12,244 Puerto Rican crested toad tadpoles to be released in the wild, supporting species recovery efforts.
This marks Brookfield Zoo Chicago's largest tadpole count from a single breeding cycle. Over the last decade, the Zoo has contributed nearly 40,000 Puerto Rican crested toad tadpoles to island-wide recovery efforts led by the Puerto Rican Crested Toad Conservancy (PRCTC) in partnership with the Puerto Rico Department of Natural and Environmental Resources (DRNA), the U.S. Fish and Wildlife Service (USFWS), and 16 accredited zoos and aquariums.
"Conservation work like this can be incredibly detailed and time-consuming, but that's what makes these milestones so meaningful," said Mike Masellis, Brookfield Zoo Chicago lead animal care specialist.
"From carefully coordinating breeding pairs to hand-counting thousands of tadpoles and tracking toads in the field, every step plays an important role in helping restore this species. Our hope is that years from now, some of these tadpoles will return to the breeding ponds as adults and continue establishing future generations in the wild."
(Click for video)
^Behind\ the\ scenes\ at\ Brookfield\ Zoo\ Chicago,\ a\ record-breaking\ conservation\ milestone\ is\ helping\ secure\ the\ future\ of\ one\ of\ the\ world's\ most\ imperiled\ amphibians.\ Months\ of\ meticulous\ care\ and\ coordination\ enabled\ Brookfield\ Zoo\ Chicago\ to\ successfully\ breed\ and\ raise\ 12,244\ Puerto\ Rican\ crested\ toad\ tadpoles\ to\ support\ species\ recovery\ efforts\ in\ the\ wild\ led\ by\ the\ Puerto\ Rican\ Crested\ Toad\ Conservancy\ (PRCTC).\ Credit:\ Brookfield\ Zoo\ Chicago^
The Puerto Rican crested toad is the only toad native to Puerto Rico and was once thought to be extinct in the wild. Today, the species persists through one of the world's longest-running amphibian reintroduction efforts but remains listed as endangered by the International Union for Conservation of Nature (IUCN), threatened by the USFWS, and endangered by DRNA.
Primary threats include habitat loss, invasive species, rising sea levels, and saltwater intrusion into breeding wetlands. The last naturally occurring population remains in the Guánica Commonwealth Forest in southwestern Puerto Rico.
Each year, breeding is carefully timed to align with Puerto Rico's rainy season, when survival conditions are highest for tadpoles released into the wild.
The months-long process involves close coordination with conservation partners to manage recommended breeding pairs for population biodiversity and mimic seasonal environmental changes to encourage breeding behaviors.
Once counted and transported to Puerto Rico, tadpoles are placed into managed aquatic habitats where they are monitored through metamorphosis before dispersing into the surrounding landscape.
Last fall, two Brookfield Zoo Chicago animal care specialists traveled to Puerto Rico to support the PRCTC's field conservation efforts at a release site. Working alongside conservation partners, the team spent a week monitoring toads to better understand habitat use, predator pressures, and environmental conditions affecting survival after reintroduction.
Brookfield Zoo Chicago currently cares for about 20 Puerto Rican crested toads, most of which are cared for behind the scenes as part of conservation efforts.
Earlier this year, guests were able to see two of these toads on habitat in "The Swamp" for the first time, offering a new opportunity to connect with a species that has gained global recognition in recent years. Millions of fans were introduced to Puerto Rico's only native toad as a visual part of Puerto Rican artist Bad Bunny's Grammy Award-winning album "DeBí Tirar Más Fotos."
Guests can learn more about Puerto Rican crested toads and Brookfield Zoo Chicago's conservation efforts by visiting The Swamp, watching the latest episode of Wild Rounds with Dr. Mike, and exploring more at brookfieldzoo.org/animals/puerto-rican-crested-toad.
Banner image: Poison dart frog of the species Ranitomeya aetherea, described from the Juruá River Basin, western Amazon, in 2023. Image courtesy of Alexander Mônico.
Scientists race to study the Amazon’s frogs before they disappear
- The Amazon is home to the world’s greatest amphibian diversity, with an estimated 1,525 species, of which only 810 have been formally described by science.
- This megadiversity is under pressure from climate change and human activity, threatening the risk of species going extinct before scientists even get a chance to describe them.
- Recent research indicates that the combination of increased temperature and exposure to pesticides can alter tadpoles’ growth and development in the Amazon.
- Amphibians play a central role in controlling insects, including disease-transmitting mosquitoes, while also contributing to natural control of agricultural pests — a service valued in Brazil at more than a billion dollars annually.
MANAUS, Brazil — Crouched over the leaf litter, where dry leaves accumulate on the forest floor, a researcher tries to capture a distinct croak using a directional microphone. Identifying the sound of a small frog is often one of the conclusive proofs that a new species has been found. It’s nighttime. He wears long clothing as protection against mosquitoes and ants, and boots to keep his feet dry. Finding amphibians in the Amazon doesn’t require high-tech equipment; it actually dates back to explorations by early-20th-century naturalists.
That’s how biologist Igor Kaefer, a professor at the Federal University of Amazonas in Brazil, describes a typical day of fieldwork in search of amphibians in the Amazon. Kaefer was part of a group responsible for describing Amazophrynella bilinguis in 2019. The very description of the little toad gives an idea of how difficult it is to find: females measure about 2 centimeters (less than an inch), and their brown head and back make them “disappear” among the leaves and branches.
Home to an estimated 1,525 species of amphibians, the Amazon Basin is the most diverse ecosystem in the world when it comes to frogs, an order that includes toads and tree frogs. However, occurrence records have been confirmed for only about 810 of those. So going into the field and finding a new-to-science species is not unlikely.
“In almost every inventory conducted in a remote area, you come back with more than one new species for synthesis,” Kaefer says.
But finding a species in the field, analyzing it, and publishing the description takes “at least five,” he adds.
This constant stream of new-to-science discoveries masks another fact: from 2001 to 2010, only 12% of studies on Brazilian amphibians focused on Amazonian species, compared to 60% in the Atlantic Forest. This shows that studies are concentrated in Brazil’s southeast and points out some of the difficulties of conducting research in the world’s largest tropical rainforest, such as limited infrastructure, hard-to-reach areas, and lack of personnel.
“Biologists who know about amphibians are the real threatened species in the Amazon,” Kaefer says.
More than 2,000 amphibian species are threatened worldwide, making them the most vulnerable group of vertebrates on the planet. Of this total, 48% are directly threatened by habitat loss. This adds another layer of complexity to the knowledge gap regarding Amazonian amphibians: we may be losing entire populations before we even know they exist.
Biologist Guilherme Azambuja searches for tadpoles in a puddle in the Amazon. Image courtesy of Guilherme Azambuja.
Why are there so many species of amphibians in the Amazon?
Viewed from above, the Amazon Rainforest looks like a seamless green block, but it’s composed of a mosaic of distinct habitats: dry land, floodplains, streams, and seasonally flooded areas. This heterogeneity is even more pronounced when it comes to amphibians that are just a few centimeters long. Even in a stretch of forest that seems homogeneous to the human eye, some variations regarding moisture, forest height, soil type, and water type are decisive for amphibians.
“Over millions of years, species have diversified and specialized in these many habitats and in different environmental conditions,” Kaefer says. “This means that they have adapted in very distinct ways to different places. Even within a large group of amphibians, we find species with differences that are very subtle but enough for us to recognize a new one.”
The most significant example of these subtle differences is found in species from the genus Synapturanus, called disc frogs because of their round, flat profiles. These species live underground and have short reproductive periods, which makes them difficult to observe. Lineages that used to be seen as a single species are now only distinguished by approaches that combine genetic examination, vocalization monitoring and bone analysis based on 3D models.
Neblinaphryne imeri, a species described only in 2024, from Pico da Neblina. Image courtesy of Taran Grant.
It was precisely this diversity that attracted Kaefer to the Amazon. Originally from the southern state of Rio Grande do Sul, he arrived in Manaus, the capital of Amazonas state, in 2008 to pursue his doctoral studies, accompanied by his friend, Daiani Kochhann, now a professor at the State University of Vale do Acaraú, in Ceará state. While Kochhann’s career was focused on the study of Amazonian fish, she was convinced by her colleague to invest in the little frogs as well — a field where scientists still have much to discover.
Kochhann says Amazonian diversity isn’t defined only by the sheer number of species, but also includes the richness of reproductive behaviors. She cites the case of frogs, which most schoolchildren are taught go through two life stages, first as tadpoles, before metamorphosing into adults.
“In the Amazon, however, some species face very complex variations regarding this pattern, such as parental care, or tadpoles that hatch from the egg and live freely right away,” Kochhann says. “Some lay eggs in water; others in damp soil. And there are species that we only know in their adult phase, whose tadpoles we have never seen.”
These differences also pose a challenge for Kochhann’s research area of physiology: scientists need to know these organisms’ functions and processes, from cells to tissues and organs. Above all, they need to understand how they function in the face of increasing environmental strain, including climate change impacts.
“When we talk about climate change and amphibians, the big questions are which species will survive, which will not, and how this process will occur,” Kochhann says. “In the case of amphibians, the urgency is greater because they have characteristics that make them especially vulnerable to rising temperatures and drier climates, such as cutaneous respiration, which depends on skin moisture. Having little data on the Amazon means not understanding enough about these processes and risks.”
Data from Brazil’s National Council for Scientific and Technological Development (CNPq) indicate that only five groups in the country’s Northern region, which includes much of the Brazilian Amazon, formally study amphibians in their research; three of them are systematically focused on amphibian ecology and physiology.
A search by Mongabay found 9,062 scientific articles on Amazonian amphibians published in the last 10 years, only 3% of which explicitly describe new species. Climate, on the other hand, has been a central topic in the scientific literature: the keyword comes up in 3,411 of the papers, even though a data gap persists regarding amphibians’ tolerance to higher temperatures and their adaptive capacities.
Adult female of the species Ranitomeya aetherea, described from the Juruá River Basin, western Amazon, in 2023. Image courtesy of Alexander Mônico.
Climate change and pesticides: Emerging extinction risks
Climate change scenarios for the Amazon region include not only hotter days but also more severe periods of drought, as already observed in 2023-2024. Studies indicate that the increase in prolonged drought will cause an increase in habitat loss of up to 33% for frogs.
In addition to this risk, climate change interacts with other factors that also affect amphibians, such as water contamination by pesticides and heavy metals. Biologist Guilherme Azambuja investigates precisely these interactions, which are still little explored in the literature on the Amazon.
“One of the biggest challenges I faced was the lack of studies in this field for tropical environments such as the Amazon,” he says. “We end up resorting to results obtained in Europe or North America, which compromises comparisons with our reality.”
The darker colors show the areas of the planet with higher projected risks for frog species due to increased aridity. Image courtesy of Wu et al., 2024.
In a paper published in February this year, Azambuja tested the isolated effects of warming and exposure to the insecticide methomyl — an extremely toxic substance used in crops, with high water solubility — on tadpoles from two species, Osteocephalus taurinus and Scinax ruber. In a second phase, exposure to methomyl was tested at two temperatures: 26.5° and 30° Celsius (79.7° and 86° Fahrenheit).
In both species, the higher temperatures reduced the animals’ final mass. “When the temperature increases, their metabolism accelerates, hindering mass gain,” Azambuja says.
With higher temperatures and faster metabolism, tadpole respiration also increases, which may explain their greater susceptibility to absorbing substances present in water in warmer scenarios. In the case of O. taurinus, the link was clear: heat doubled methomyl’s lethal toxicity.
But the results also showed there are no absolutes in nature, with species responding differently to multiple stress factors. In terms of lethality, the tree frog S. ruber proved to be sensitive to methomyl regardless of temperature.
For Azambuja, this variation between species is the central point. It is precisely because species diversity is so high that responses to the same conditions also vary. Therefore, the lack of knowledge about these animals and their lifestyles means we can’t fully understand the impacts of these challenges or which species may be at greater risk.
In any case, Azambuja says, adaptation to temperature or substances takes a toll on amphibians, even the most resistant ones. “Body size decreases, resulting in thinner and smaller animals. While they are resistant, they may have lower sexual fitness and face reproductive challenges. Sometimes an animal tolerates warmer environments but remains at a level of stress that may not be sustainable in the long run, leading to organism collapse,” he says.
Harlequin toads of the species Atelopus spumarius, endemic to the Amazon. Image courtesy of Jaime Culebras/ASI.
What are we about to lose?
Making the case for amphibian conservation can be difficult: considered “disgusting” by society, these little frogs face invisible threats, and their contribution to ecosystems is rarely appreciated. At the Federal University of Ceará, Karoline Ceron is trying to change this reality with a powerful argument: money.
“By proposing research to assign economic value to amphibians in Brazil, we want to work alongside those who influence decision-making in the country, considering agribusiness’s major role in policymaking,” she says. “We want to establish a dialogue between two worlds: that of conservation and that of production.”
Still in progress, her research estimates that amphibians help prevent $1.18 billion in agricultural losses in Brazil, simply by consuming insects that attack crops. In soy plantations in the Cerrado biome, for example, amphibians likely save around half a million dollars a year in pesticides, by eating approximately 300 million invertebrates in those areas.
They also play a role in public health, especially in the tropics. With amphibians’ decline, part of the natural control of disease vectors like mosquitoes, which can transmit malaria and dengue fever, becomes lost. Research conducted across Central America found an increase in malaria cases related to the loss of amphibian populations.
“There is a synergistic risk, therefore,” Ceron says. “Loss of amphibian populations can lead to increased use of pesticides and insecticides in both rural and urban areas, which in turn would create new contamination and environmental poisoning.”
This story was first published here in Portuguese on April 13, 2026.
Banner: Secretarybird. Photo: Ronelle Visagie, Author provided (no reuse)
Birds of prey in South Africa are in trouble – a study analyses data from 16 years of road counts
Birds of prey and vultures (raptors) play a vital role in ecosystems, both as top predators and key scavengers. However, compared to many other bird species, raptor populations are declining faster. This is because they need large areas to live in, have low population densities, and reproduce slowly. For these reasons they are vulnerable to human impacts like farming with pesticides, electrocution, collision with wind turbines, or poaching.
In many cases, by the time scientists and conservationists fully understand how bad the declines are, it may be too late to act. Thus, having good population monitoring is vital to act as an early warning system of declines. Many countries in the global south host important populations of raptors but lack effective monitoring programmes.
Africa is an important continent for raptor diversity. Several studies across Africa have used road counts (counting birds from repeated transects across routes) to monitor how raptor populations have changed over time. A recent study went one step further, combining trends from these different surveys from across Africa to better understand these changes at a pan-African scale. Unfortunately, no data from South Africa were available to be incorporated into this analysis.
Monitoring on the road.
In our recent study we took advantage of data that was collected by one dedicated fieldworker, Ronelle Visagie, who drove nearly 400,000 km (the distance from Earth to the moon) across the central area of South Africa (see map) between 2009 and 2025, while she worked for the Birds of Prey Programme of the Endangered Wildlife Trust.
Map of the study area showing the distribution of all road counts conducted between 2009 and 2025. The black polygon indicates the core survey area.
During these 16 years, Ronelle counted all the raptors and large birds that she saw on these work trips. Comparing how the rate of these observations (numbers of individuals per 100km driven) changed over time allowed us to explore species population trends. We had enough data to examine trends for 18 raptors and eight other large bird species over this period. Unfortunately, we did not find a good news story.
These road counts revealed that 50% of the species (13 out of 26) declined significantly, while only three species (12%) showed significant increases. The remaining ten species (38%) showed no significant trends (see Figure 2).
The declining trends raise serious concerns about the conservation status of several species in a region known to host important raptor populations. Thus, urgent conservation actions are needed, especially for species declining by more than 50%. Given that several of these species are not currently listed as threatened either globally or regionally, their conservation status may need to be reassessed.
Fig.2: Estimated population change for 26 species from road counts between 2009 and 2025 in South Africa. (a) Negative and (b) positive trends. The dashed vertical black line indicates a −50% population change. Author provided (no reuse)
Trends in raptor populations
According to our results, 42% of the assessed species declined by more than 50% in the last 16 years.
Notable declines included all of the three migratory species assessed (lesser kestrel, amur falcon and steppe buzzard). These trends match other studies from their breeding grounds in the northern hemisphere, which also suggested declines. Protecting migratory species is especially challenging because action may be needed in breeding areas, non-breeding areas, and along migration routes, where the threats they face may differ.
We also found declines of several resident raptors, including jackal buzzard, Verreaux’s eagle and secretarybird. Populations of these species declined by over 50% in our study region.
In contrast, populations of white-necked raven, greater kestrels, and white-backed vulture increased. The latter is a critically endangered species, but seems to be increasing within our study area.
Amur Falcon. Ronelle Visagie, Author provided (no reuse)
Some of the trends we detected were similar to a recent study that explored raptor population trends from across Africa using similar approaches to our study. For example, our findings of large declines for secretarybird and lesser kestrel were very similar to those reported in Kenya and Botswana. Additionally, similar population changes for secretarybird were detected during winter (but not summer) using road counts in the Nama Karoo (a major part of our study area) during the period just before our study (a 61% decline between the late 1980s and early 2010s). This suggests that the decline detected earlier may have continued into the mid-2020s.
Secretarybird. Megan Murgatroyd, Author provided (no reuse)
We compared the direction of trends (whether species numbers were going up or down) from our road counts and the Southern African Bird Atlas Project (SABAP2). But only about half of the trends agreed between the two methods (road counts and the bird atlas). Species with consistent trends between the methods included amur falcon and lesser kestrel – both showing declines – and greater kestrel and white-backed vulture – both showing increases. Species with inconsistent trends all showed decreases according to our road counts but increases according to the bird atlas project. These included Ludwig’s bustard, blue crane, secretarybird, black-winged kite, and southern pale chanting goshawk.
If we assume that our road counts trends are reliable, these findings suggest that although the bird atlas project data can provide valuable information on the changes in distribution of birds, atlas data may be less well suited to capture changes in abundance at large spatial scales and across multiple species.
Across Africa, declines in birds of prey are often linked to human population growth, agricultural expansion and climate change. In our study area, there have been no major recent changes in land use or population density, but more subtle or long-term human impacts may be driving these changes.
Conflicts between people and raptors, including illegal killings, could play a role. Climate change and infrastructure like power lines and wind farms are adding further pressure by fragmenting aerial habitat and affecting survival and reproduction.
Read more: Finding space for both wind farms and eagles in South Africa
Trends in human populations
Ronelle Visagie. Author provided (no reuse)
Human populations in Africa are expected to grow significantly over the next three decades, which will increase pressure on biodiversity.
Given the projected human population growth in Africa (79%), and a corresponding rise in demand for resources and energy, threats to vulnerable bird species are likely to get worse.
Gareth Tate. Author provided (no reuse)
It is therefore essential that we have reliable tools to monitor species trends and better understand the impacts of these pressures.
This is crucial for understanding the current biodiversity crisis and preventing severe wildlife loss.
Ronelle Visagie and Gareth Tate of the Endangered Wildlife Trust contributed to this research.
A program is returning burrowing owls back to their natural habitat
The Upper Nicola Band released 11 captive-born owls in spax̌mn — part of a decade-long effort to reinstate the tiny birds of prey whose populations have plummeted
Pluto, an 11-year-old educational burrowing owl with the Burrowing Owl Conservation Society of BC, is pictured at N’kwala School’s gym in spax̌mn (Douglas Lake), B.C., on April 22, 2026. Photo by Aaron Hemens
This story is a collaboration between IndigiNews and The Narwhal.
Nine-year-old John Smithers cradles a tiny burrowing owl in his hands, preparing to release it into the grasslands of Upper Nicola Band (UNB) territory.
Like other young syilx people, he’s grown up hearing stories about the small birds of prey whose populations have plummeted in the region in the last century or so.
The owls – known in syilx culture as guardians, guides or messengers – were “once a common element” in landscapes stretching from the southern Interior of “B.C.” all the way to Manitoba, according to “Canada’s” Committee on the Status of Endangered Wildlife.
Now, burrowing owl sightings are rare. In 2003, the Government of Canada listed the burrowing owl as endangered under the federal Species at Risk Act. Experts link the bird’s decline to the gradual loss of its grassland habitats over the last century.
According to the Burrowing Owl Alliance, the bird’s population in the country has declined by over 96 per cent since 1987.
“Lots of animals can come and get them,” Smithers said about the lack of protective habitat for the burrowing owl.
John Smithers, a nine-year-old student from Upper Nicola Band’s N’kwala School, prepares to release a captive-born burrowing owl down an artificial nesting burrow and into the wild, during a release event for 11 captive-born owls into the community’s owl restoration site in spax̌mn (Douglas Lake) on April 22, 2026. Photo by Aaron Hemens
Earlier this year, Smithers became N’kwala School’s annual student ambassador to a regional burrowing owl recovery program that’s being led by the First Nation.
As ambassador, he was invited to be the first person of the year to release a captive-born burrowing owl into the wild on April 22, in his home community of spax̌mn (Douglas Lake) in “B.C.’s” Nicola Valley.
The release, which coincided with Earth Day, marked 10 years since UNB began releasing captive-born burrowing owls onto their homelands.
In return, those captive-raised owls have produced 125 “wild-born” baby owls — or fledglings — since being released from the community’s restoration site.
Despite high winds and the risk of ticks, dozens of excited people from all age groups turned out in high spirits for the release.
Students, nature enthusiasts and Elders alike shared laughs and smiles at the sight of the precious birds, with their round heads, short stature and long legs.
Upper Nicola Band Elder Howard (Howie) Holmes prepares to release a captive-born burrowing owl down an artificial nesting burrow and into the wild, during a release event for 11 captive-born owls into the community’s owl restoration site in spax̌mn (Douglas Lake) on April 22, 2026. Photo by Aaron Hemens
Framed by grassy hills, Smithers released the first owl under the warm sunshine with the help of Dawn Brodie, one of the main field technicians who has been involved in the program since its inception.
The nervous bird nearly escaped from his grasp and into the open air. But thanks to the quick reflexes of Brodie, her helping hands connected the captive-born owl back to the land and down an artificial nesting burrow that had been prepared by the UNB stewardship department.
“Soft” is the word Smithers used to describe the feeling of holding the owl.
Soon after, several guests in attendance – from program partners to Youth and Elders – were invited by the field technicians to release an owl down different burrows that were created by the recovery program and its partners.
Some of the owls wore amusingly bewildered expressions as they waited in the gentle grasp of human hands before being placed into a burrow.
A captive-born burrowing owl prior to being released into an artificial nesting burrow, during the release event for 11 captive-born owls into the Upper Nicola Band’s burrowing owl restoration site in spax̌mn (Douglas Lake) on April 22, 2026. Photo by Aaron Hemens
In total, 11 captive-born owls — six males and five females — were released into five of the site’s 35 artificial burrows that day. They are all just under one year old.
“The program has exceeded all our expectations,” said Loretta Holmes, a UNB member and senior resource technician with the band’s stewardship department.
“The owls, which we call sq̓əq̓axʷ, have responded better than we dared to hope ten years ago. And community interest and involvement has been strong since the start.”
Underground burrows protect, allow for monitoring of owls
The tiny burrows are connected through a network of underground tunnels hidden under the grassland hills above spax̌mn.
Each artificial burrow consists of a small, corrugated tube in the ground that serves as its entrance, which feeds into the larger network of tunnels. The entry points are camouflaged in the field by grass and large rocks.
Artificial nesting burrows are scattered throughout the grassland hills above Upper Nicola Band, at the community’s burrowing owl restoration program site in spax̌mn (Douglas Lake) on April 22, 2026. Photo by Aaron Hemens
Before any captive-raised owls are released, handfuls of frozen mice are inserted into the burrows and tunnels.
“That helps them not have to go as far to hunt as often. It encourages them to lay more eggs, and helps them rear their young ones when they’re hatched,” said Holmes.
Once released, the burrow entrances are closed off for a few days, explained Chris Gill, a project biologist with the band’s Species-at-Risk program.
“It’s to let them acclimatize and calm down, basically. And potentially bond with the mate that’s in there,” said Gill.
Breeding gets underway as soon as two owls choose each other as mates, and Gill said that eggs are laid in June.
The burrow tunnels, which protect the owls from predators, are connected to a nest box. The nest box has an opening at ground level, allowing technicians to observe how many eggs have been laid and monitor activity.
Technicians also attach leg bands to the newly-hatched birds here, to track future migration.
Mice are also delivered to the burrows two to three times a week. Holmes said that this type of care results in nests that carry nine to 10 eggs — more than the average of six to eight laid by burrowing owls in the wild.
The mice are “giving them a big head start and maximizing the chances of producing healthy fledglings, and healthy parents as well,” Gill said.
The owls stay in the site’s burrow network from anywhere from four days to up to a week, depending on weather conditions, and are then free to fly around in the open air.
“They mostly stick at the site, even after you release them out of the burrow, because they’re now used to the site,” said Gill.
“They may have paired up, or they may choose another mate from the site.”
Chris Gill, a project biologist with the Upper Nicola Band’s Species-at-Risk program, speaks at the playground of N’kwala School, prior to the release event for 11 captive-born owls into the community’s burrowing owl restoration site in spax̌mn (Douglas Lake) on April 22, 2026. Photo by Aaron Hemens
By July, fledglings will start to emerge from the burrows, and the owls usually start to migrate south in September and October. They’ll return to the breeding sites next April.
Tracked migration data from burrowing owls who left the site in previous years revealed that the birds travel as far as “San Jose, California.”
“It’s just so amazing that they went all the way somewhere, wintered in those conditions and came back,” said Holmes.
“It’s wonderful.”
UNB program part of larger effort to bring back owls
In the last decade, more than 100 burrowing owls have been raised in captivity at the Kamloops Wildlife Park by the Burrowing Owl Conservation Society, before being released at spax̌mn. There’s a site in “Oliver” that supports the program as well.
The captive-raised owls all come with identification tags on their legs, which are documented by field technicians before they are released into the burrows.
Two captive-born burrowing owls from the Kamloops Wildlife Park — one female and one male — are transported to their artificial burrow nesting sites for release at the burrowing owl restoration site in spax̌mn (Douglas Lake), B.C., on April 22, 2026. Photo by Aaron Hemens
Many of the 125 wild-born owls have left the UNB site and returned, including four who came back this spring; two males and two females, three of which were born at the site last year.
While the conservation efforts are helping to re-populate the burrowing owl species in this part of the country, UNB views this work as only one piece of the larger puzzle of how to protect the community’s rare and sensitive grassland ecosystem habitats.
By stewarding these ecosystems — and restoring and supporting the biodiversity that has been depleted — it’s also an act by the band to protect their cultural identity and fulfill generational responsibilities around caring for the land and for all living things.
“Conserving a species at risk, like a burrowing owl, it’s about far more than a single bird or species. It’s about upholding relationships, responsibilities and balance with the living world,” said Holmes.
Animals like the burrowing owl are part of an interconnected system that has sustained Indigenous Peoples for generations, she said.
Loretta Holmes, an Upper Nicola Band member and senior resource technician with the band’s stewardship department, wears owl-themed earrings made by a Kamloops-based Indigenous artist, during the release event for 11 captive-born owls into the site in spax̌mn (Douglas Lake) on April 22, 2026. Photo by Aaron Hemens
“If one species declines, it signals that the relationship between people and the land is out of balance. Conservation becomes an act of restoring harmony and respect in that system,” she said.
“Protecting species at risk aligns with Indigenous laws that emphasize caretaking. Conservation efforts honour the principle that decisions made today must ensure the healthy lands and wildlife for our relatives yet to come.”
It’s just one of many projects under the community’s stewardship department’s larger Species-At-Risk program, which is designed to protect and restore endangered species populations on their lands.
The program also looks at restoration efforts for species including American badger, Lewis’s woodpecker and Great basin spadefoot — all of which have been federally recognized as threatened or endangered.
Penticton Indian Band — a fellow syilx community that’s under the Okanagan Nation Alliance (ONA) along with UNB — also released burrowing owls through their own similar program that same week.
“In British Columbia, burrowing owls are extirpated. That means that they’re not actually existing on the landscape without reintroduction programs, like the Upper Nicola Band’s,” said Gill.
A captive-born burrowing owl is released into an artificial nesting burrow, during the release event for 11 captive-born owls into the Upper Nicola Band’s burrowing owl restoration site in spax̌mn (Douglas Lake) on April 22, 2026. Photo by Aaron Hemens
But Traditional Ecological Knowledge gathered from Elders and advisors confirmed that burrowing owls historically existed on the spax̌mn landscape.
In 2015, a year before the burrowing owl recovery program launched, the Species-At-Risk team conducted surveys on reserve lands to determine a suitable habitat for the birds.
They settled on the grasslands above the UNB community as the reintroduction program’s site.
The grassland ecosystem landscape above the Upper Nicola Band community is the site of their burrowing owl restoration program, pictured in spax̌mn (Douglas Lake) on April 22, 2026. Photo by Aaron Hemens
“We found suitable habitat for burrowing owls — but no burrowing owls present,” said Gill.
The birds traditionally nested in the underground burrows that were dug and abandoned by different animals, from badgers to marmots and coyotes, he said
Because of a lack of badgers, Gill said there weren’t any natural burrows out on the land.
“That’s why the Upper Nicola Band put in these artificial burrows,” he said.
“There are actually badgers on that reserve, but there are very few — and far in-between — so we can’t rely on a burrowing owl finding a badger burrow.”
According to the province, “several small” burrowing owl nesting sites were identified in the Okanagan and Thompson valleys from 1900 to 1928.
Historical nesting areas include Osoyoos, Oliver, Penticton, White Lake, lower Similkameen Valley, Vernon, Kamloops and Douglas Lake.
Artificial nesting burrows are scattered throughout the grassland hills above Upper Nicola Band, at the community’s burrowing owl restoration program site in spax̌mn (Douglas Lake) on April 22, 2026. Photo by Aaron Hemens
But between 1928 and 1980, only four nesting sites were recorded.
The federal government attributed the “conversion of grassland to cropland” as the “ultimate factor responsible for the decline in burrowing owls.” It estimates that the species experienced a 90 per cent population decline from 1990 to 2000.
Also contributing to the owl’s population decline is the “gauntlet” of issues they face on their migration route, Holmes said.
This includes fatalities occurring from collisions with wind turbine farms and motor vehicles. Pesticides targeting insects and rodents that the birds feed upon indirectly poisons them as well.
In 2004, the estimated population of burrowing owls in “Canada” was recorded at 795 mature individuals. In 2015, it had plunged to approximately 270.
Burrowing owl populations are “in a nose dive,” said Gill.
He called the burrowing owl “a canary in a coal mine” in measuring the state of ecosystem health.
“A badger, a burrowing owl — those species are the indicator species. If they’re not doing well, then that’s a sign of something bigger that’s not doing well,” he said.
Grasslands are also endangered
Along with Holmes and Brodie, Gill helped initiate the burrowing owl reintroduction program 10 years ago. He called the two women “the work horses” of the program.
“We monitor the owls, and write really good data collection on it,” said Brodie, a veterinary technician who supports the program as a burrowing owl consultant.
The program has been a success, Gill said, not just because of the region’s “great grasslands.”
“But it’s also the stewardship that’s going on with these owls,” he said.
“It’s one of the most productive sites in B.C. for releasing our fledging owls.”
In the wild, burrowing owls can live anywhere from four to six years, according to Lauren Meads, the executive director of the Burrowing Owl Conservation Society of BC.
Meads, who was joined at the release event by the society’s 11-year-old educational burrowing owl, Pluto, added that in captivity they can live up to 15 years.
A student from N’kwala School in spax̌mn (Douglas Lake), B.C., pets Pluto, an 11-year-old educational burrowing owl with the Burrowing Owl Conservation Society of BC, at the school gym on April 22, 2026. Photo by Aaron Hemens
[According to the Government of B.C](https://www2.gov.bc.ca/assets/gov/environment/plants-animals-and-ecosystems/spe
An Atlantic Forest treefrog, Aplastodiscus leucopygius, at the edge of a rocky forest stream in Brazil's Atlantic Forest, transitioning between aquatic and terrestrial environments. New research led by Penn State biologists found that amphibians in connected natural forests and aquatic habitats were more likely to host beneficial skin microbes that inhibit a deadly fungal pathogen. Credit: Shannon Buttimer, Penn State
Maintaining connections between natural habitats may support beneficial microbes that help wildlife defend against disease. In a new study of tropical amphibians, a team led by Penn State biologists found that amphibians in connected natural forests and aquatic habitats were more likely to host beneficial skin microbes that inhibit a deadly fungal pathogen. But when these habitats become spatially separated due to planted crops, infrastructure development or other human land use, those microbial defenses weaken and pathogen infection levels can increase with potentially deadly results.
The findings, published in the journal Proceedings of the National Academy of Sciences, reveal a previously underappreciated link between landscape connectivity, beneficial microbes and disease resistance in wildlife, according to the researchers.
"Animals rely not only on their immune systems, but also on beneficial microbes that live on their bodies and help protect them from pathogens," said Gui Becker, associate professor of biology in the Eberly College of Science at Penn State and senior author of the study.
"Our results show that when natural habitats become disconnected, these microbial defenses can be disrupted."
The researchers explained that habitat loss and fragmentation are widely recognized as major drivers of biodiversity decline, but scientists are increasingly realizing that environmental change can also alter the microbiome—the community of microbes that live in and on animals and often play key roles in health and immunity.
A fragmented rainforest landscape in Brazil's Atlantic Forest. Credit: Renato Martins
"Our study provides evidence that connectivity among habitats is essential for maintaining multiple levels of biodiversity, from host-associated bacteria with protective functions to their respective host species," said first author Daniel Medina, previously a postdoctoral scholar in Becker's lab at Penn State and currently a lecturer in tropical forest ecology and resource management at The School for Field Studies.
"It highlights a critical link between environmental disturbance, microbial defenses and disease dynamics."
To investigate the connection between habitat fragmentation and animal microbiomes, the researchers studied amphibian populations in Brazil's Atlantic Forest, a biodiversity hotspot that has experienced extensive habitat alteration. Many amphibians depend on both forest habitats and aquatic breeding sites, requiring them to move between these environments during different stages of their life cycle.
The researchers focused on a phenomenon that Becker—a member of the Penn State One Health Microbiome Center—previously coined as "habitat split," where natural forests and aquatic habitats become separated by agriculture, development or other land uses.
Across multiple frog species—collected from 40 sampling sites during the amphibian breeding season—the team found that animals living in landscapes with higher habitat split hosted fewer bacteria known to inhibit the deadly fungus, Batrachochytrium dendrobatidis, which has caused dramatic amphibian declines worldwide. In some species, infection levels of the fungus also increased as habitat split intensified.
"We showed such a link by indicating that spatial separation between critical habitats, such as natural forests and aquatic breeding sites, may impair amphibians' ability to recruit protective skin bacteria that defend against the fungus," Medina said.
Becker Lab researchers conducting fieldwork in Brazil's Atlantic forest. Credit: Augusto Gomes / João Marcos Rosa
The researchers propose that in intact landscapes, animals regularly encounter both environmental microbes and low levels of pathogens, which may help maintain microbial communities capable of suppressing disease. When natural habitats become disconnected, those ecological interactions can break down.
Although the study focused on amphibians, the researchers said the findings could extend to many other animals that depend on multiple habitats throughout their life cycles.
"These results suggest that connected landscapes allow animals to maintain microbiomes that are better equipped to fight pathogens," Becker said.
"Many species—from migratory birds to fish and large mammals—move among different habitats as they feed, breed or disperse. When those habitats become disconnected, it may not only affect movement but also alter how animals interact with beneficial microbes and pathogens."
Tropical treefrog Boana faber along an Atlantic Forest stream. Credit: Augusto Gomes / João Marcos Rosa
Restoring and maintaining ecological connectivity between multiple classes of natural environments could serve as a critical strategy not only for fostering genetic diversity in wildlife populations but also for supporting the natural microbial defenses that help them resist disease.
This could include habitat restoration strategies such as protecting riparian zones—vegetation-rich areas at the edges of bodies of water—and reconnecting riparian habitats to larger areas of natural terrestrial vegetation, according to Becker.
"Protecting habitat connectivity may help preserve multiple layers of biodiversity, from the animals we see to the microbial communities that help keep them healthy," Becker said.
The new amphibian species, with the scientific name Gastrotheca mittaliiti, measures 2.7 to 3.3 centimeters (1 to 1.3 inches).
Scientists have discovered a new species of miniature marsupial frog in the Peruvian Amazon that carries its young in a natural pouch on its back, a research institute reported Wednesday.
The new amphibian species, with the scientific name Gastrotheca mittaliiti, measures 2.7 to 3.3 centimeters (1 to 1.3 inches) and was discovered in a mountainous ecosystem in the Amazonas region bordering Ecuador.
The frog is bright green and has small protuberances on its back. The number of specimens in the wild is not known.
Its pouch enables the marsupial frog to nurture its young rather than, as other frogs, rely on aquatic environments for egg development.
The study says the amphibian is at "high risk" because its habitat is suffering the effects of climate change and the impact of fires started by farmers clearing the region.
"This is further evidence of the enormous natural wealth we possess... If we continue our research, there are many species still waiting to be discovered," Manuel Oliva, director of the Ceja de Selva Research Institute for Sustainable Development, part of the Toribio Rodriguez de Mendoza National University, told AFP.
The discovery was published in the New Zealand scientific journal Zootaxa and undertaken in collaboration with research departments at Florida International University and the University of Seville in Spain.
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