cross-posted from: https://lemmygrad.ml/post/11842509

'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.

Getty Images

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.

Getty Images

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.

cross-posted from: https://lemmygrad.ml/post/11831906

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

cross-posted from: https://lemmygrad.ml/post/11831859

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.

When they’re being eaten, bean plants release chemicals that draw in parasitic wasps.

https://www.science.org/doi/10.1126/sciadv.aec3229

A plant immune receptor mediates tritrophic interactions by linking caterpillar detection to predator recruitment

cross-posted from: https://lemmygrad.ml/post/11799050

Banner image of a koala by Bernard Spragg. NZ via Flickr (CC0).

Australia has the money to protect nature. It just isn't spending it, expert says

“I think the international community really does need to put more pressure on Australia to do better,” says Euan Ritchie, a professor of wildlife ecology and conservation at Deakin University in Australia, in a recent episode of Mongabay’s Newscast.

From animals like kangaroos, koalas and platypuses, to plants like waratah, kangaroo paw and climbing heath, Australia has exceptionally high biodiversity, with a unique assemblage of wildlife found nowhere else on the planet.

The Australian government claims the country is on track to meet many of its targets under the Kunming-Montreal Global Biodiversity Framework, the landmark agreement that aims to halt and reverse the decline of biodiversity, and ensure the sustainable use of biodiversity equitable sharing of benefits, among other goals, by 2050.

However, Ritchie, who’s also the president of the Australian Mammal Society and a councilor for the country’s Biodiversity Council, argues that “Australia is failing miserably” on all those measures. This is despite Australia being one of the wealthiest nations on Earth in terms of GDP per capita, with a “huge number of really knowledgeable scientists,” he tells Newscast host Mike DiGirolamo.

“If we look at the number of threatened species in Australia, it’s more than 2,200 now, and that list continues to increase,” Ritchie says. “We have ecosystems that are collapsing, 17 in total within Australia and two more further south into sub-Antarctic and Antarctic regions that are collapsing.”

The iconic koala (Phascolarctos cinereus) is also now endangered in the states of Queensland and New South Wales, and in the Australian Capital Territory (ACT), he adds.

Ritchie and other researchers argue that just 1% of Australia’s annual federal budget, or about A$7 billion ($5 billion), would help save the country’s threatened species and protect ecosystems. However, Australia’s latest annual budget allocates only 0.06% to nature conservation — and this is expected to decline in the future.

At the same time, the government is estimated to spend more than A$26 billion ($19 billion) annually to support or subsidize harmful industries like fossil fuels, DiGirolamo says.

One of the government’s strategies to finance nature protection is to create a “nature repair market,” a voluntary biodiversity market, where industry and private players can earn biodiversity certificates.

A biodiversity market would be very complex to navigate and get right, Ritchie says. Instead, he says Australia should just pony up the money for conservation, which he says it can “afford to [at] a much larger degree today.”

Surveys by the Biodiversity Council also show that 95% of Australians polled support the increased government spending on the environment.

“Australia is a sovereign nation. It’s really rich. If we want to fund something that we think is really important, the government could literally do that today,” Ritchie says. “It’s just a case of whether they have the political appetite to do that.”

Listen to the full conversation with Euan Ritchie here.

https://sci-bot.ru/

kinda like perplexity with scientific papers in sci-hub database, what it writes is irrelevant but pulled citations are neat

cross-posted from: https://lemmygrad.ml/post/11782002

New miniature bright-orange toadlet found in southern Brazil and named after Lula

In a small stretch of the Atlantic Forest in southern Brazil lives a bright-orange species of frog that’s new to science, researchers report in a recent study. The miniature amphibian measures just over a centimeter long, less than half an inch, or the length of an average fingernail.

The team has named the toadlet Brachycephalus lulai, in honor of Brazil’s president, Luiz Inácio Lula da Silva.

The genus Brachycephalus, also called flea toads or saddleback toads, are all tiny and live among leaf litter in Brazil’s Atlantic rainforest. Of the 42 known species, 35 have been described since 2000.

Individuals of the latest species to be described, B. lulai, were found hidden in the leaf litter of the montane Atlantic Forest at two nearby sites on the southeastern slopes of Serra do Quiriri in the state of Santa Catarina, southern Brazil.

The researchers collected 32 individuals and compared different features of the frogs, including their DNA and vocalizations, with those of other Brachycephalus species. Their analysis showed that it was indeed a new-to-science species.

B. lulai has a bright-orange body dotted with tiny green and brown spots. Males measure just 8.9-11.3 millimeters (0.35-0.44 inches) in length, while females are slightly larger at 11.7-13.4 mm (0.46-0.53 inches). The males produce a very distinct call to attract females that’s unique to the species, the researchers found.

Currently, the sites where B. lulai was found appear to be intact, without any significant threats. As such, the researchers suggest the species be categorized as least concern under the IUCN Red List classification.

“The new species occurs in highly preserved forests that are very difficult to access, which means it is not threatened with extinction,” Marcos R. Bornschein, study co-author from the Institute of Biosciences at São Paulo State University, told Popular Science. “It is one of the few Brachycephalus species that are not threatened, which is very reassuring for us.”

However, “it is essential to continue systematically monitoring this scenario,” the researchers write. This is because the broader Serra do Quiriri range — which includes threatened frog species like B. quiririensis, B. auroguttatus, and Melanophryniscus biancae — faces impacts from regular burning of grasslands, cattle grazing, mining, invasion of pine trees, and development for tourism.

Banner image: The newly described Brachycephalus lulai. Image courtesy of Luiz Fernando Ribeiro.

cross-posted from: https://lemmygrad.ml/post/11752742

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."

According to the theory of special relativity it IS possible to view two objects moving faster than the speed of light relative to each other. You may think this is not the case but, let me explain. I saw this get confused in a lemmy thread and wasn't setup to post there so I'll clarify here for the interested.

Consider the following: observer A sees a craft B moving right at 0.6c, and another craft D moving left at 0.6c such that they are on a collision course.

B------> <------D

          A

what I'm asserting is A does observe B and D moving at 1.2c relative to each other. The Lorenz transformation is not needed! People get tripped up, but the setup gives away the answer. A sees nothing moving faster than c relative to A so there is no violation of theory.

Special relativity becomes relevant here when determing what is observed in reference frames other than ones own, i.e. B or D. Based on what A sees, it seems like B should see D moving at 1.2c , but applying the lorenz transformation to get B's perspective we see that it doesn't, and everything is seen as slower than c.

B observes A moving at 0.6c, and D at something like, idk, 0.85c (length contraction along the axis of travel is especially relevant here).

   B <---------D

<------A

Just as easily this setup could involve objects moving away from each other and could represent distant objects being pushed away from eachother by the expansion of the universe. The neat thing there is that once they're far enough to cross the horizon above c, they'll never see each other because the light isn't fast enough to cross the gap, so conventiently a violation still isn't observed!

https://en.wikipedia.org/wiki/Observable_universe

light emitted by objects currently situated beyond a certain comoving distance (currently about 19 gigaparsecs (62 Gly)) will never reach Earth.

cross-posted from: https://lemmygrad.ml/post/11751324

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.

cross-posted from: https://lemmygrad.ml/post/11712543

Banner image: The Common wombat (Vombatus ursinus) frequents the western side of Cawleys Bridge, and it is hoped the bridge will reinforce the wombat population in Royal National Park. Image courtesy of Simone Cottrell / DCCEEW.

Above an Australian highway, a bridge reconnects wilderness for quolls, koalas and other animals

• A new wildlife overpass that spans a major highway south of Sydney is reconnecting habitat between Heathcote National Park and Royal National Park, helping animals safely cross one of Australia’s busiest road corridors.
• The retrofitted bridge includes features for a wide range of species, from rope crossings for gliding marsupials to vegetated pathways for ground-dwelling animals such as wombats, echidnas and amphibians.
• Ecologists say reconnecting fragmented habitat is increasingly important as roads, urban expansion, extreme weather events and climate-driven bushfires isolate wildlife populations and reduce genetic diversity.
• Research from Australia and elsewhere shows that wildlife crossings can significantly reduce animal deaths and help species move, forage and breed, but only when these structures are carefully designed around animals’ behavior and habitat needs.

SYDNEY, Australia. At dusk on the edge of the bush in Australia’s Heathcote National Park, a spotted-tailed quoll lowers its tawny head to the ground, pink nose twitching. The dense forest, the scent of damp earth and eucalyptus leaf litter gives way, abruptly, to heat and a chemical tang. Ahead: open space. Noise. Light.

A car zooms past, loud and fast. It doesn’t slow down. None of the vehicles do. It’s unlikely any driver going 110 kilometers per hour (68 miles per hour) would notice the brown, cat-sized quoll, camouflaged with white spots that beautifully blend into its native bush home.

Forty thousand vehicles a day move along this stretch of the M1 Princes Motorway — four lanes of fast-moving traffic that slice between Heathcote National Park on one side and Royal National Park on the other.

This is the primary route from Sydney to industrial centers in the southern part of the state of New South Wales, and there’s heavy truck traffic.

The quoll (Dasyurus maculatus) waits at the highway’s edge for a break that doesn’t come.

Headlights streak. Engines roar. The air pulses with pressure and speed. Crossing here isn’t just dangerous — it’s nearly impossible. The highway might as well be a canyon.

And yet, on the other side of the road lies something essential: new territory that includes more of the bird eggs and the rabbits that quolls eat, and mates with more varied DNA, both essential for long-term survival.

For decades, quolls, wallabies, deer, koalas and other animals have died trying to cross this highway. More than 200 have perished in just five years, but this number only includes larger species because smaller animals are hard to count.

But now, just above the traffic, a new, safe path is taking shape.

A koala (Phascolarctos cinereus) in eucalyptus tree on the Woronora Plateau, west of Cawleys Bridge. Image courtesy of DCCEEW.

A bridge across a river (of cars)

On a late summer afternoon in early March, I stand on the nearly completed Cawleys Bridge, a wildlife overpass-to-be that stretches above the roadway. It’s an ordinary structure that’s being transformed into something far more ambitious. Below, cars flash by and the sound is a constant, oceanic whoosh. Around me, the bridge smells of fresh soil — dark, mineral-rich earth recently spread across its surface.

Heavy machinery moves slowly back and forth, laying the final layers of habitat. State transport workers position massive tree trunks into place — logs arranged as architecture to form a new kind of ecosystem, one that’s designed to serve a wide variety of native species.

While the structure’s combination of features is new, its design is based on previously built wildlife bridges and the research proving that animals use them.

The science will continue. Motion-sensing cameras are already installed at entry points and along the crossing, ready to document which animals venture across the remodeled bridge, and how many.

Early monitoring, before the retrofit, showed just how inhospitable the bare bridge had been before modification. “When we monitored it, in [Australian] winter, nothing was using it,” said Kylie Madden, an ebullient ecologist with the New South Wales Environment and Heritage agency. “In summer, we did get a few crossings of these goannas [lizards], and we had one ringtail possum. But it was such an unfriendly situation.”

Now, the previously animal-unfriendly, plain-concrete bridge — once used only for road-maintenance vehicles — has been transformed into habitat that feels more like home. And its design allows for a huge variety of species to cross.

Ecologist Bob Crombie and DCCEEW ecologist Kylie Madden, who worked to make Cawleys Bridge a reality for years, met in person for the first time on the bridge. Image courtesy of DCCEEW / Alex Pike.

All animals considered: The scaly, the diminutive and the arboreal

High above the ground, thick draped ropes stretch across open air, intended for arboreal marsupials like sugar gliders (Petaurus breviceps) and common ringtail possums (Pseudocheirus peregrinus) — species that prefer to move through the forest on tree branches well above the forest floor. “There’s absolutely no way a sugar glider will make it across that road without connection,” Madden said.

Below the graceful ropes, there’s a wooden pathway for animals that typically like to travel just above the ground, including reptiles and koalas.

At the base, soil and native plantings will form a continuous vegetated corridor for ground dwellers: wombats (Vombatus ursinus), echidnas (T__achyglossus aculeatus), amphibians and insects. They’ll be funneled toward the bridge and away from the road by two long “wings” of fencing that run perpendicular to the bridge.

“We’re trying to make this functional for everything,” Madden said, leading me over to soft mats of coral fern that are habitat for the many species living at the road’s edge. “There are endangered species, like the red crowned toadlet [Pseudophryne australis] within just 10 meters [33 feet] of this bridge.” Madden crouched down to check for the tiny toads under the ferns next to a roped-off patch of ground marked with bright orange flags. “But they are never crossing without this structure.”

These tiny amphibians, no bigger than a thumb, live among the damp understory. Without cover, without continuity, the road is either a dead end or a death trap for them.

DCCEEW’s Kylie Madden and Bob Crombie, a retired Royal National Park ranger and ecologist, pored over a hand-drawn map from 1978. It identified the connections between Heathcote National Park to the west and Garrawarra State Conservation Area to the east, which leads into Royal National Park. Image courtesy of DCCEEW / Alex Pike.

Uniting two iconic national parks

Experts say there’s an urgent need for these crossings. Royal National Park is the world’s second-oldest park, opened in 1879. But despite its size — 150 square kilometers (58 square miles) — it’s increasingly isolated. To the east lies the Pacific Ocean; to the west, a vast and continuous expanse of bushland stretching across the Woronora Plateau, toward the Eastern Highlands that separate inland Australia from the coast. Between them: the highway.

“It’s iconic,” Madden said of Royal. “But what it’s not connected to — because of the M1 — is this vast tract of wilderness.”

Even highly mobile animals struggle when habitat is fragmented by infrastructure. Madden said wombats are almost extinct within the national park, while still relatively common on the other side of the road.

Koalas (Phascolarctos cinereus) were once present in the park, but they’ve all but disappeared. “There’s habitat there,” Madden said, “but almost no koalas.” Some populations remain on the eastern side. But without safe passage, they can’t recolonize the park — especially after a fire like the one that decimated Royal National Park in 1994.

That blaze was catastrophic, burning through more than 90% of the forest. In the decades since then, bushfires have increased in frequency, intensity and size, driven by hotter and drier conditions induced by climate change, according to CSIRO, Australia’s federal science agency. Experts say the park is likely to burn again.

“We need to really make sure our reserves are connected,” Madden said, “for all species … to make them as resilient as possible for the future.”

This map of Cawleys Bridge and Princes Motorway shows how the bridge links Heathcote National Park to the Garrawarra State Conservation Area, which leads into Royal National Park. Image courtesy of DCCEEW.

Reconnecting fractured landscapes is key to the future health of wildlife. In a study outlining the need to reconnect nature, biologist Stuart Pimm and colleagues wrote that, “Even when natural habitats remain, they often come in fragments too small or isolated to sustain viable populations.”

When animals can move safely throughout their entire range, they avoid inbreeding: There’s a larger choice of mates, which increases genetic diversity. This bestows stronger defense to fight off disease and the ability to adapt to environmental changes, including climate change.

It also means that if there’s a bushfire in one area, animals can escape, either settling elsewhere or rebuilding populations in burned areas afterward.

But without connection, these animals might as well be living on islands.

An aerial shot documented Cawleys Bridge before the final bridge “furniture” and plants were installed. Image courtesy of Transport for NSW.

Making it happen

The idea for Cawleys Bridge emerged from years of growing awareness, pressure and collaboration. Bob Crombie, now a retired ranger at Royal National Park, originally raised the idea in 1974. It was then taken up by a local branch of the Country Women’s Association and the National Parks Association. In 2021, the Sutherland Shire Environment Centre joined the coalition, and they began working with Transport NSW, the state’s transportation agency. Public concern over the plight of koalas helped push the project forward.

“In 2022, the idea of retrofitting Cawleys Bridge to reconnect Heathcote and Royal National Park came up in discussions,” Sally Webb, an official at Transport NSW, told Mongabay in an email

Now, she said, there are regular meetings between the transportation and environment agencies “to discuss how we can contribute to implementing the NSW Koala Strategy.” This government initiative, launched in 2021, centers on protecting koalas and their habitats.

By late 2023, the wildlife bridge had secured internal approval from four government agencies. The NSW Koala Strategy funded the bridge conversion, including A$800,000 (nearly $600,00) for construction and maintenance and A$75,000 (about $54,000) for monitoring. The result is the hybrid structure that stands today, combining multiple crossing types into a single span: fencing to direct animals, ramps, ground cover, climbing structures and aerial rope systems.

Across New South Wales, such crossings are still rare. Cawleys is just the second wildlife bridge in the Sydney area, which is a biodiversity hotspot. It’s the only one to link disconnected landscape between national parks.

There are 10 wildlife crossings along Australia’s heavily populated east coast, and Transport NSW has more than 25,000 records of animals using them. Most are underpasses, which are far less costly to build or retrofit than bridges.

Data from the agency’s Fauna Connectivity Database show that across 29 road projects nationwide, at least 67 species use crossings, including threatened animals like koalas and potted-tailed quolls, as well as more common ones, like emus (Dromaius novaehollandiae).

For ecologists, the lesson is clear: Animals will use these structures — but only if they feel safe.

Bob Crombie, retired ecologist and former NPWS park ranger, on Cawleys Bridge, which he first envisioned retrofitting for wildlife passage back in 1974. Image courtesy of DCCEEW / Alex Pike.

A proven connection

Animal-friendly crossings directly address the significant impact human development has on native species.

“One of the primary drivers of global landscape fragmentation is road construction,” said Brendan Taylor, a wildlife ecologist and author of the book The Evolution of Wildlife Crossings in Eastern Australia. He likened it to “casting a net over the landscape, with each road separating formerly connected habitats.”

That idea came from Road Ecology: Science and Solutions, a game-changing 2003 book by Richard T.T. Forman and other noted ecologists. “That book was part of the growing movement to better understand and assess the impact of roads on wildlife populations,” Taylor said. Wildlife crossings, whether bridges or underpasses, are attempts to cut holes in that net, he added, in order to “perforate the roaded corridor,” allowing animals to move, forage and breed.

When combined with fencing that keeps animals off the roadway and directs them toward a crossing, extensive research shows that these structures greatly reduce hazardous accidents and animal deaths.

Thousands have been built throughout Europe, with 600 in the Netherlands alone, and more than 1,000 in the U.S. and Canada. In the Brazilian Amazon, there’s now a primate canopy bridge. Kenya has constructed underpasses for elephants, and Singapore has built green bridges for various mammals. Crossings and culverts are being retrofitted into existing roads, and in many places, new roadways consider wildlife movement from the design stage, like the Delhi-Mumbai Expressway.

Connectivity is critical for the survival of many species. But crossings aren’t one-size-fits-all. The infrastructure needs to address the movements of different species and their preferences. That requires habitat-specific research.

Conservation biologist Ross Goldingay has spent years studying animals including Australia’s eastern pygmy possum (Cercartetus nanus), a small, tree-dwelling marsupial. Despite its diminutive size — about 12 centimeters (5 inches) from head to tail — pygmy possums can travel up to 500 meters (1,640 feet) in a single night. Their movements benefit the landscape as they feed on pollen and nectar and pollinate plants and trees. Like many forest-dwelling and prey species, they’re reluctant to move through open spaces.

The tiny and widely loved eastern pygmy possum is one of the smallest pouched animals. The Royal National Park, to the east of the bridge, is a hotspot for these miniature marsupials. Image courtesy of Kerri-Lee Harris / DCCEEW.

“If you want to try and maintain connectivity, you need to assist these animals. So how do you get them over a road?” Goldingay asked.

For the past three decades, his research has focused on exactly that. He’s conducted multiyear surveys to figure out what design elements are needed for animals to use crossings. He learned that installing tall wooden poles helps gliding possums cross gaps in the forest, including roads. In monitoring underpasses along the coast, he saw that a wide range of mammals regularly use them.

“Landscaping really matters,” Goldingay said. He’s found that pygmy possums, like other bush creatures, seek out plants for cover. His research has demonstrated that “where you’ve got the vegetation coming up … you’ll get more animals passing through.” Without it, crossings can fail.

His research also confirmed that rope bridges can ensure that arboreal animals such as squirrel gliders (Petaurus norfolcensis) have crossings that suit their habits: They can’t use underpasses. Animals that like to travel off the ground but not in the treetops — including koalas and the endangered broad-headed snake (Hoplocephalus bungaroides) — need another type of crossing.

Going over the road is just one solution. Some animals are going under, using existing culverts that were constructed when roads were built, usually to channel rainwater underneath. In one study for Transport NSW, Taylor and his colleagues counted 36 species, from frogs to wallabies, that used even simple drainage pipes, just 1 m (3 ft) wide, to cross beneath roadways.

Now, new “fauna sensitive” road construction guidelines in NSW include larger culverts, when appropriate, offering a cost-effective alternative to more expensive bridges.

A spotted-tailed quoll (Dasyurus maculatus). Image by John Harrison. CC BY-SA 3.0

Looking ahead

Back on the bridge in the long light of late April, which is early autumn here in New South Wales, the dump trucks and transport workers are gone. Aside from the steady thrum of cars below, all is quiet. Work on Cawleys Bridge is complete and the final pieces of a living corridor have fallen into place.

While the traffic below remains unchanged — fast, loud and relentless — above, there is a carefully constructed thread linking two vast landscapes.

It will take time, but studies show that animals find and use these bridges, adding them to their memory banks and teaching their young. “Animals learn to use these pathways over time,” said Madden, the ecologist, “and that’s what a passage across a dangerous roadway is” — a pathway.

For spotted-tail quolls, koalas, tiny sugar-glider possums and so many other animals, a bridge like this may be the difference between turning back from — or dying on — a “canyon of a road” or crossing into new territory.

cross-posted from: https://lemmygrad.ml/post/11678176

Zoo reaches historic milestone for Puerto Rican crested toad conservation efforts with more than 12,000 tadpoles

^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.

cross-posted from: https://lemmygrad.ml/post/11605995

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.

cross-posted from: https://lemmygrad.ml/post/11595844

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.

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Read more: Nigeria’s Hadejia wetlands are a vital stopover for migrating birds: new survey records species found in the park

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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.

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Read more: Finding space for both wind farms and eagles in South Africa

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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.

cross-posted from: https://lemmygrad.ml/post/11595681

Banner image: The golden mantella, an endangered frog species found only in Madagascar. Image by Frank Vassen via Wikimedia Commons (CC BY 2.0).

Africa’s amphibians are overlooked in conservation planning, experts warn

Herpetologists are calling for greater inclusion of amphibians in African conservation planning, in a recent letter published in the journal Science.

Africa is home to roughly 1,170 known species of amphibians, 99% of which are endemic. Some 37% of the amphibians are recognized as threatened with extinction.

The researchers note that amphibians — frogs, salamanders and caecilians — are especially important as early-warning detectors of ecological disruption, given their sensitivity to pathogens, thermal stress, pollution and hydrological changes in their wetland habitats. Yet amphibians as a group remain poorly represented in protected-area planning and management tools in Africa, the authors write. They note there are only 12 documented amphibian-specific action plans across the continent. These include a conservation plan for frogs in Cape Town, South Africa, and for the golden mantella frog (Mantella aurantiaca) in Madagascar.

The Democratic Republic of Congo (DRC), for example, doesn’t yet have conservation action plans specifically dedicated to amphibians, according to the letter’s lead author, Bienvenu Mwale, an expert on amphibians in the DRC and Cameroon. “To date, the DR Congo existing legal frameworks remain broad and give limited attention to this taxonomic group, with a stronger focus on large mammals,” Mwale told Mongabay by email.

Cameroon, on the other hand, has given full protection to six amphibian species, including the Goliath frog (Conraua goliath), the world’s largest, through a ministerial decree. This could be a good model for African conservation planning, Mwale said.

He added that several African amphibian species are currently classified as data deficient on the IUCN Red List, meaning there’s not enough information to assess their conservation status.

“One of the needs for amphibian conservation plans in Africa (that citizens can help with) is specific information on distribution,” Amaël Borzée, a co-author of the letter and member of the Amphiban Specialist Group at the IUCN, the global wildlife conservation authority, told Mongabay by email. “This is something anyone can help with, and for instance, doing it through the iNaturalist platform is a great way for people to get engaged. This is easy: take a picture of any amphibian and upload it on iNaturalist, and the job is done, and it helps.”

Karen Lips, an amphibian expert not affiliated with the letter, told Mongabay in an email: “I agree that much more research and much more conservation is needed in Africa. It is a continent with incredible richness of biodiversity, but still needs research to understand patterns of distribution and threats to that biodiversity.

“Africa is one of the regions with the least amount of information on amphibian population biology, meaning that we are not able to assess how land use change, climate change, disease, or other factors affect those species, because we have no baseline population data for comparisons,” Lips added.