Interrupted flows in the Murray River endanger frogs

17 01 2023

Flooding in the Murray-Darling Basin is creating ideal breeding conditions for many native species that have evolved to take advantage of temporary flood conditions. Led by PhD candidate Rupert Mathwin, our team developed virtual models of the Murray River to reveal a crucial link between natural flooding and the extinction risk of endangered southern bell frogs (Litoria raniformis; also known as growling grass frogs).

Southern bell frogs are one of Australia’s 100 Priority Threatened Species. This endangered frog breeds during spring and summer when water levels increase in their wetlands. However, the natural flooding patterns in Australia’s largest river system have been negatively impacted by expansive river regulation that some years, sees up to 60% of river water extracted for human use.

Our latest paper describes how we built computer simulations of Murray-Darling Basin wetlands filled with simulated southern bell frogs. By changing the simulation from natural to regulated conditions, we showed that modern conditions dramatically increase the extinction risk of these beloved frogs.

The data clearly indicate that successive dry years raise the probability of local extinction, and these effects are strongest in smaller wetlands. Larger wetlands and those with more frequent inundation are less prone to these effects, although they are not immune to them entirely. The models present a warning — we have greatly modified the way the river behaves, and the modern river cannot support the long-term survival of southern bell frogs.’

Read the rest of this entry »




Influential conservation papers of 2022

3 01 2023

Following my annual tradition, I present the retrospective list of the ‘top’ 20 influential papers of 2022 as assessed by experts in Faculty Opinions (formerly known as F1000). These are in no particular order. See previous years’ lists here: 2021, 2020, 201920182017201620152014, and 2013.


Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals — “… this paper adds a much-needed perspective to the status of genetic diversity and adaptive potential in contemporary populations.

Habitat, geophysical, and eco-social connectivity: benefits of resilient socio-ecological landscapes — “… distinguishes four distinct but interrelated types of connectivity: landscape, habitat, geophysical, and eco-social connectivity, of which the fourth type is new. The authors discuss how these different types of connectivity are related to ecosystem services and disservices, and how they interact with each other to influence landscape sustainability issues.

Glyphosate impairs collective thermoregulation in bumblebees — “… low-dose glyphosate, combined with global increases in temperature, converge to disrupt homeostatic regulation in bee colonies. This is a crucial revelation for understanding the loss of bees across the globe, as they serve as major pollinators in nature and agriculture.

Human disturbances affect the topology of food webs — “… provides great opportunities for the study of food web structures, their dynamics and stability under different human influences.

A comprehensive database of amphibian heat tolerance — “provides estimates of amphibian upper thermal limits – a relevant trait for assessing the vulnerability of this highly-threatened group of ectotherms to rising temperatures – derived from thousands of experimental studies.”

Read the rest of this entry »




Error-free genetic repositories: case of amphibians

18 08 2020

In our new study, we curated > 39,000 amphibian mitochondrial DNA (mtDNA) sequences from GenBank, identified > 2,000 sequencing and taxonomic errors, and published the quality-checked records as a curated dataset with an automated workflow in R. High-quality genetic data should help quantify and protect the diversity of the most threatened vertebrate group on Earth.

frogs

Upper left: species of Boophis from Andasibe, Madagascar. Upper right: Dendropsophus anceps from State of Rio de Janeiro, Brazil. Lower left; Dendropsophus bipunctatus from State of Rio de Janeiro, Brazil. Lower right: Bufo bufo from Gelderland, The Netherlands. All images from the author.

Scientists from a broad range of biological disciplines use genetic information like DNA sequences to test ecological and evolutionary hypotheses. Critically, genetics are today essential for naming species and therefore quantifying biodiversity, as well as determining where species live and how many individuals of a species occur in the wild.

Researchers are routinely asked, and more recently frequently required, by scientific journals to submit their DNA sequences to GenBank (among other public repositories of genetic data) as a requirement for publishing a paper. Although GenBank provides some quality controls (e.g., to filter sequences with bacterial contaminants and those from other kingdoms), authors are responsible for the quality of their genetic data and have full freedom to assign these to species in the taxonomy database of GenBank. Notably, once sequences have been deposited in GenBank, records are rarely updated in light of identified errors often resulting from taxonomic progress.

Two important notions emerge from the former status quo: Read the rest of this entry »





Amphibian conservation in a managed world

1 04 2020

FrogBlog2

Crinia parinsignifera (top) and Limnodynastes tasmaniensis (bottom). Photo: Kate Mason

The amphibian class is diverse, and ranges from worm-like caecilians to tiny frogs that live their entire lives within bromeliads high in the rainforest canopy. Regardless of form or habit, all share the dubious honour of being cited as the world’s most endangered vertebrate taxon, and 41% of the species assessed are threatened with extinction. Rapidly changing climates will further exacerbate this situation as amphibians are expected to be more strongly affected than other vertebrates like birds or mammals.

This peril stems from a physiological dependence on freshwater.

Amphibians breathe (in part) through their skin, so they maintain moist skin surfaces. This sliminess means that most amphibians quickly dry out in dry conditions. Additionally, most amphibian eggs and larvae are fully aquatic. One of the greatest risks to populations are pools that dry too quickly for larval development, which leads to complete reproductive failure.

This need for freshwater all too often places them in direct competition with humans.

To keep pace with population growth, humans have engineered a landscape where the location, and persistence of water is tightly controlled. In seeking water availability for farming and amenity, we all too often remove essential habitats for amphibians and other freshwater fauna.

To protect amphibians from decline and extinction, land managers may need to apply innovative techniques to support vulnerable species. With amphibians’ strong dependence on freshwater, this support can be delivered by intelligently manipulating where and when freshwater appears in the landscape, with an eye to maintaining habitats for breeding, movement and refuge. A range of innovative approaches have been attempted to date, but they are typically developed in isolation and their existence is known only to a cloistered few. A collation of the approaches and their successes (and failures) has not occurred.

In our latest paper, we used a systematic review to classify water-manipulation techniques and to evaluate the support for these approaches. Read the rest of this entry »





Microclimates: thermal shields against global warming for small herps

22 11 2017

Thermal microhabitats are often uncoupled from above-ground air temperatures. A study focused on small frogs and lizards from the Philippines demonstrates that the structural complexity of tropical forests hosts a diversity of microhabitats that can reduce the exposure of many cold-blooded animals to anthropogenic climate warming.

Luzon forest frogs

Reproductive pair of the Luzon forest frogs Platymantis luzonensis (upper left), a IUCN near-threatened species restricted to < 5000 km2 of habitat. Lower left: the yellow-stripped slender tree lizard Lipinia pulchella, a IUCN least-concerned species. Both species have body lengths < 6 cm, and are native to the tropical forests of the Philippines. Right panels, top to bottom: four microhabitats monitored by Scheffers et al. (2), namely ground vegetation, bird’s nest ferns, phytotelmata, and fallen leaves above ground level. Photos courtesy of Becca Brunner (Platymantis), Gernot Kunz (Lipinia), Stephen Zozaya (ground vegetation) and Brett Scheffers (remaining habitats).

If you have ever entered a cave or an old church, you will be familiar with its coolness even in the dog days of summer. At much finer scales, from centimetres to millimetres, this ‘cooling effect’ occurs in complex ecosystems such as those embodied by tropical forests. The fact is that the life cycle of many plant and animal species depends on the network of microhabitats (e.g., small crevices, burrows, holes) interwoven by vegetation structures, such as the leaves and roots of an orchid epiphyte hanging from a tree branch or the umbrella of leaves and branches of a thick bush.

Much modern biogeographical research addressing the effects of climate change on biodiversity is based on macroclimatic data of temperature and precipitation. Such approaches mostly ignore that microhabitats can warm up or cool down in a fashion different from that of local or regional climates, and so determine how species, particularly ectotherms, thermoregulate (1). To illustrate this phenomenon, Brett Scheffers et al. (2) measured the upper thermal limits (typically known as ‘critical thermal maxima’ or CTmax) of 15 species of frogs and lizards native to the tropical forest of Mount Banahaw, an active volcano on Luzon (The Philippines). The > 7000 islands of this archipelago harbour > 300 species of amphibians and reptiles (see video here), with > 100 occurring in Luzon (3).

Read the rest of this entry »





The Evidence Strikes Back — What Works 2017

16 01 2017

Bat gantry on the A590, Cumbria, UK. Photo credit: Anna Berthinussen

Bat gantry on the A590, Cumbria, UK. Photo credit: Anna Berthinussen

Tired of living in a world where you’re constrained by inconvenient truths, irritating evidence and incommodious facts? 2016 must have been great for you. But in conservation, the fight against the ‘post-truth’ world is getting a little extra ammunition this year, as the Conservation Evidence project launches its updated book ‘What Works in Conservation 2017’.

Conservation Evidence, as many readers of this blog will know, is the brainchild of conservation heavyweight Professor Bill Sutherland, based at Cambridge University in the UK. Like all the best ideas, the Conservation Evidence project is at once staggeringly simple and breathtakingly ambitious — to list every conservation intervention ever cooked up around the world, and see how well, in the cold light of evidence, they actually worked. The project is ongoing, with new chapters of evidence added every year grouped by taxa, habitat or topic — all available for free on www.conservationevidence.com.

What Works in Conservation’ is a book that summarises the key findings from the Conservation Evidence website, and presents them in a simple, clear format, with links to where more information can be found on each topic. Experts (some of us still listen to them, Michael) review the evidence and score every intervention for its effectiveness, the certainty of the evidence and any harmful side effects, placing each intervention into a colour coded category from ‘beneficial’ to ‘likely to be ineffective or harmful.’ The last ‘What Works’ book included chapters on birds, bats, amphibians, soil fertility, natural pest control, some aspects of freshwater invasives and farmland conservation in Europe; new for 2017 is a chapter on forests and more species added to freshwater invasives. Read the rest of this entry »





Killing us slowly

6 07 2010

I’m currently attending the 2010 International Congress for Conservation Biology in Edmonton, Canada. I thought it would be good to tweet and blog my way through on topics that catch my attention. This is my second post from the conference.

I silently scoffed inside when the plenary speaker was being introduced. It was boldly claimed that we were about to hear one of the best presentations any of us had ever seen at a scientific conference before.

I cannot say for certain whether it was indeed ‘the best’, but bloody hell, it was excellent.

Our speaker is certainly well-known in the endocrinology world (very well published), is a bane to certain chemical industries and is revered as a scientist who puts his money where is mouth is.

Professor Tyrone Hayes of the University of California Berkeley is an ‘eco-endocrinologist’ who blew the lid on the devastating health effects of the most available and ubiquitous agricultural herbicide in use today – evil atrazine. As my readers know, I am certainly pushing the empirical basis for the link between environmental degradation and deterioration of human health (my talk here at the ICCB on Wednesday will be on this very topic), so this topic interests me greatly.

It’s no secret that atrazine has devastating feminising effects on amphibians (and many other taxa), and has been linked convincingly to increasing the risk of cancer in humans. It’s banned in Europe, but still widely used pretty much everywhere else. Read the rest of this entry »





Crap environmental reporting

13 11 2009

EvilWe do a lot in our lab to get our research results out to a wider community than just scientists – this blog is just one example of how we do that. But of course, we rely on the regular media (television, newspaper, radio) heavily to pick up our media releases (see a list here). I firmly believe it goes well beyond shameless self promotion – it’s a duty of every scientist I think to tell the world (i.e., more than just our colleagues) about what we’re being paid to do. And the masses are hungry for it.

However, the demise of the true ‘journalist’ (one who investigates a story – i.e., does ‘research’) in favour of the automaton ‘reporter’ (one who merely regurgitates, and then sensationalises, what he/she is told or reads) worldwide (and oh, how we are plagued with reporters and deeply in need of journalists in Australia!) means that there is some horrendous stories out there, especially on scientific issues. This is mainly because most reporters have neither the training nor capacity to understand what they’re writing about.

This issue is also particular poignant for the state of the environment, climate change and biodiversity loss – I’ve blogged about this before (see Poor media coverage promotes environmental apathy and untruths).

But after a 30-minute telephone interview with a very friendly American food journalist yesterday, I expected a reasonable report on the issue of frog consumption because, well, I explained many things to her as best I could. What was eventually published was appalling.

Now, in all fairness, I think she was trying to do well, but it’s as though she didn’t even listen to me. The warning bells should have rung loudly when she admitted she hadn’t read my blog “in detail” (i.e., not at all?). You can read the full article here, but let me just point out some of the inconsistencies:

  • She wrote: “That’s a problem, Bradshaw adds, because nearly one half of frog species are facing extinction.”

Ah, no. I told her that between 30 and 50 % of frogs could be threatened with extinction (~30 % officially from the IUCN Red List). It could be as much as half given the paucity of information on so many species. A great example of reporter cherry-picking to add sensationalism.

  • She wrote: “Bradshaw attributes the drop-off to global warming and over-harvesting.”

Again, no, I didn’t. I clearly told her that the number one, way-out-in-front cause of frog declines worldwide is habitat loss. I mentioned chytrid fungus as another major contributor, and that climate change exacerbates the lot. Harvesting pressure is a big unknown in terms of relative impact, but I suspect it’s large.

  • She continued: “Bradshaw has embarked on a one-man campaign to educate eaters about the frog leg industry”

Hmmm. One man? I had a great team of colleagues co-write the original paper in Conservation Biology. I wasn’t even the lead author! Funny how suddenly I’m a lone wolf on a ‘campaign’. Bloody hell.

“Aghast”, was I? I don’t recall being particularly emotional when I told her that I found a photo of Barack Obama eating frog legs during his election campaign. I merely pointed this out to show that the product is readily available in the USA. I also mentioned absolutely nothing about whales or their loins.

So, enough of my little humorous whinge. My point is really that there are plenty of bad journalists out there with little interest in reporting the truth on environmental issues (tell us something we don’t know, Bradshaw). If you want to read a good story about the frog consumption issue, check out a real journalist’s perspective here.

CJA Bradshaw





Continuing saga of the frogs’ legs trade

10 08 2009

© D. Bickford

© M. Auliya

In January we had a flurry of media coverage (see here for examples) about one of our papers that had just come out online in Conservation BiologyEating frogs to extinction (Warkentin et al.). I blogged about the paper then (one of ConservationBytes’ most viewed posts) that described the magnitude of the global trade in amphibian parts for human food. Suffice it to say, it’s colossal.

A couple of months ago, John Henley of the Guardian (UK) rang me to discuss the issue some more for a piece he was doing in that newspaper. The article has just come out (along with a companion blog post), and I can honestly say that it’s the most insightful coverage of the issue by the media I’ve seen yet. Thanks, John, for covering it so well. The article is excellently written, poignant and really gets to the heart of the matter – people just don’t know how bad the frog trade really is for amphibian biodiversity.

Short story – don’t eat any more frogs’ legs (you probably won’t be missing much).

I’ve reproduced John’s article below, but please visit the original here.

Why we shouldn’t eat frogs’ legs

In the cavernous community hall of the Vosges spa town of Vittel, a large and lugubrious man, his small, surprisingly chirpy wife, and 450 other people are sitting down to their evening meal. It’s rather noisy. “Dunno why we do it, really,” shouts the man, whose name is Jacky. “Don’t taste of anything, do they? White. Insipid. If it wasn’t for the sauce it’d be like eating some soft sort of rubber. Just the kind of food an Englishman should like, in fact. Hah.”

Outside, the streets are filled with revellers. A funfair is going full swing. The restaurants along the high street are full, and queues have formed before the stands run by the local football, tennis, basketball, rugby and youth clubs.

All offer the same thing: cuisses de grenouilles à la provencale (with garlic and parsley), cuisses de grenouille à la poulette (egg and cream). Seven euros, or thereabouts, for a paper plateful, with fries. Nine with a beer or a glass of not-very-chilled riesling. The more daring are offering cuisses de grenouilles à la vosgienne, à l’andalouse, à l’ailloli. There’s pizza grenouille, quiche grenouille, tourte grenouille. Omelette de grenouilles aux fines herbes. Souffle, cassolette and gratin de grenouilles.

Everywhere you look, people are nibbling greasily on a grenouille, licking their fingers, spitting out little bones. “Isn’t it just great?” yells Jacky’s diminutive wife, Frederique. “Every year we do this. It’s our tradition. Our tribute to the noble frog.”

This is Vittel’s 37th annual Foire aux Grenouilles. According to Roland Boeuf, the 70-year-old president of the Confrererie de Taste-Cuisses de Grenouilles de Vittel, or (roughly) the Vittel Brotherhood of Frog Thigh Tasters, which has organised the event since its inception, the fair regularly draws upwards of 20,000 gourmet frog aficionados to the town for two days of amphibian-inspired jollities. Between them, they consume anything up to seven tonnes of frogs’ legs.

But there’s a problem. When the fair began, its founder René Clément, resistance hero, restaurateur and last of the great Lorraine frog ranchers, could supply all the necessary amphibians from his lakes 20 miles or so away. Nowadays, none of the frogs are even French.

According to Boeuf, Clément, whose real name was Hofstetter, moved to the area in the early 1950s looking to raise langoustines in the Saone river; the water proved too brackish and he turned to frogs instead. A true Frenchman, his catchphrase, oft-quoted around these parts, was that frogs “are like women. The legs are the best bits”.

Hofstetter/Clément would, says Gisèle Robinet, “provide 150 kg, 200 kg for every fair, all from his lakes and all caught by him”. With her husband Patrick, Robinet runs the Au Pêché Mignon patisserie (tourte aux grenouilles for six, €18; chocolate frogs €13 the dozen) on the Place de Gaulle, across the square from the restaurant Clément used to run, Le Grand Cerf. Now known as Le Galoubet, there’s a plaque commemorating the great frogman outside. “As a child I remember clearly him dismembering and preparing and cleaning his frogs in front of the restaurant,” says Robinet, who sells frog tartlets to gourmet Vitellois throughout the year, but makes a special effort with quiches and croustillants at fair-time. “It’s a big job, you know. Very fiddly. But we were all frog-catchers when I was a kid. Now, of course, that’s not possible any more.”

Boeuf recalls many a profitable frog-hunting expedition in the streams and ponds around Vittel. “One sort, la savatte, you could catch with your bare hands,” he says. “Best time was in spring, when they lay their eggs. They’d gather in their thousands, great wriggling green balls of them. I’ve seen whole streams completely blocked by a mountain of frogs.”

Others, rainettes, would be everywhere at harvest time. Or you could get a square of red fabric and lay it carefully on the water next to a lily pad that happened to have a frog on it, “and she’d just hop straight off and on to the cloth”, Boeuf says. “They love red.”

Pierette Gillet, the longest-standing member of the Brotherhood and, at 81, still a sprightly and committed frog-fancier, remembers heading out at night with a torch in search of so-called mute frogs, harder to catch because they have no larynx and hence emit no croak. “They’d be blinded by the light, and you could whack them over the head,” she says.

But those days are long gone. As elsewhere in the world, the amphibians’ habitat in France – where frogs’ legs have been a recognised and much remarked-upon part of the national diet for the best part of 1,000 years – is increasingly at risk, from pollution, pesticides and other man-made ills. Ponds have been drained and replaced with crops and cattle-troughs. Diseases have taken their toll, and the insects that frogs feed on are disappearing too. Alarmed by a rapid and dramatic fall in frog numbers, the French ministry of agriculture and fisheries began taking measures to protect the country’s species in 1976; by 1980, commercial frog harvesting was banned.

These days, a few regional authorities in France still allow the capture of limited numbers of frogs, strictly for personal consumption and provided they are broiled, fried or barbecued and consumed on the spot (a heresy not even Boeuf is prepared to contemplate). There are poachers who defy the ban; two years ago a court in Vesoul in the Haute-Saone convicted four men of harvesting vast numbers of frogs from the Mille-Etangs or Thousand Lakes area of the Vosges. The ringleader admitted to personally catching at least 10,000, which he sold to restaurants for 32 cents apiece.

By and large, though, France’s tough protection laws, enforceable by fines of up to €10,000 (£8,500) and instant confiscation of vehicles and equipment, seem to be working. As a result, all seven tonnes (officially, at least) of frogs’ legs consumed at this year’s Vittel fair have been imported, pre-prepared, deep-frozen and packed in cardboard boxes, from Indonesia.

Needless to say, this does not much please patriotic Gallic frog-fanciers. “We’d far prefer our frogs to be French, of course we would,” laments Gillet. “Especially here in the Vosges. This really is the heart of frog country.”

A Vittel restaurateur, who for obvious reasons demands anonymity, suggests there are still “ways and means” of securing at least a semi-reliable supply of French frogs for those who demand a true produit du terroir, “but it’s really not very easy, and no one here will tell you anything about it. We’d like to source locally, but the law is the law.”

But the fact that the Foire aux Grenouilles – not to mention the rest of France, and other big frog-consuming nations such as Belgium and the United States – now imports almost all its frogs’ legs has consequences that run deeper than a mere denting of national gastronomic pride. For scientists now believe that, just as with many fish species, we could be well on the way to eating the world’s frogs to extinction. Based on an analysis of UN trade data, researchers think we may now be consuming as many as 1bn wild frogs every year. For already weakened frog populations, that is very bad news indeed.

Scientists have long been aware that while human activity is causing a steady loss of the world’s biodiversity, amphibians seem to be suffering far more severely than any other animal group. It is thought their two-stage life cycle, aquatic and terrestrial, makes them twice as vulnerable to environmental and climate change, and their permeable skins may be more susceptible to toxins than other animals. In recent years, a devastating fungal condition, chytridiomycosis, has caused catastrophic population declines in Australia and the Americas.

“Amphibians are the most threatened animal group; about one third of all amphibian species are now listed as threatened, against 23% of mammals and 12% of birds,” says Corey Bradshaw, an associate professor at the Environment Institute of the University of Adelaide and a member of the team that carried out the research into human frog consumption that was published earlier this year in the journal Conservation Biology. “The principle drivers of extinction, we always assumed, were habitat loss and disease. Human harvesting, we thought, was minor. Then we started digging, and we realised there’s this massive global trade that no one really knows much about. It’s staggering. So as well as destroying where they live, we’re now eating them to death.”

France is the main culprit: according to government figures, while the French still consume 70 tonnes a year of domestically gathered legs each year, they have been shipping in as many as 4,000 tonnes annually since 1995. Besides popular, essentially local events such as the Foire aux Grenouilles, frogs’ legs are mostly a delicacy reserved for restaurants with gastronomic pretensions; one three-star chef, Georges Blanc, has at one time or another developed 19 different recipes for them at his celebrated restaurant in the Ain village of Vonnas, baking and skewering and skilleting them in everything from cream to apples.

Belgium and Luxembourg are also noted connoisseurs, but perhaps surprisingly, the country that runs France closest in the frog import stakes is the US. Frogs’ legs are particularly popular in the former French colony of Louisiana, where the city of Rayne likes to call itself Frog Capital of the World, but are also consumed with relish in Arkansas and Texas, where they are mostly served breaded and deep-fried. Bradshaw has a picture on his blog of President Barack Obama tucking with apparent gusto into a plate of frogs’ legs.

The world’s most avid frog eaters, though, are almost certainly in Asia, in countries such as Indonesia, China, Thailand and Vietnam. South America, too, is a big market. “People may think frogs’ legs are some kind of epicurean delicacy consumed by a handful of French gourmets, but in many developing countries they are a staple,” Bradshaw says.

Indonesia is today the world’s largest exporter of frogs by far, shipping more than 5,000 tonnes each year. Some of these may be farmed, but not many. Commercial frog-farming has been tried in both the US and Europe, but with little success: for a raft of reasons, including the ease with which frogs can fall prey to disease, feeding issues and basic frog biology, it is a notoriously risky and uneconomic business. Frogs are farmed in Asia, but rarely on an industrial scale; most are small, artisan affairs with which rural families try to supplement their income.

The vast majority of frogs that end up on a plate are harvested from the wild. Bradshaw and his colleagues estimate that Indonesia, to take just one exporting country, is probably consuming between two and seven times as many frogs as it sends abroad. “We have the legally recorded, international trade figures, but none of the local business is recorded,” Bradshaw says. “It’s back-of-an-envelope work. That’s what’s so alarming.”

The scientists’ biggest concern, he says, is that because of the almost complete lack of data, no one knows in what proportion different frog species are being taken. If, as they suspect, some 15 or 20 frog species are at any given moment supplying most of world demand, the consequences could be catastrophic. For while overharvesting for human consumption may not in itself be quite enough to drive a frog species to extinction, combined with all the other threats frogs face it certainly could be.

“The thing is, it isn’t a gradual process,” Bradshaw warns. “There’s a threshold, you cross it, and the whole thing crashes because you’ve just completely changed the composition of the whole community. There’s a tipping point. It’s exactly what happened with the overexploitation of cod in the North Atlantic. And with frogs, there’s no data, no tracking, no stock management. We really should have learned our lesson with fish, but it seems we haven’t. This is a wake-up call.”

Back in Vittel, Boeuf says he had no idea frogs were in such trouble. “They’re an endangered species here, I know,” he says. “That’s why we have to be careful, and we are. But if we can buy them in such quantities from Indonesia, surely it must be all right. They’re being careful there too, aren’t they?” Sadly, it would seem they are not. And all for a few greasy scraps of limp, bland flesh.

People say frogs taste like a cross between fish and chicken. In fact, they taste of frog: in other words, precious little bar the sauce they are served in.





Plight of frogs

27 04 2009

I’m off to a conference shortly, so this will be brief.

© D. Bickford
© D. Bickford

In an effort to raise awareness about the plight of amphibians (see previous posts on ConservationBytes.com regarding drivers of amphibian extinction risk and over-harvesting frogs for human consumption), the mob at SaveTheFrogs.com have initiated ‘Save The Frogs Day’ for tomorrow (28 April 2009).

I encourage people to get involved – there are some particularly good ideas for teachers and students found at the dedicated ‘Save The Frogs Day’ website.

CJA Bradshaw





Even Obama eats frog legs

3 02 2009

As the seemingly never-ending media blitz covering our paper describing the massive world trade in frog legs continues, I came across a very poignant example of how ubiquitous the trade in frog legs for human consumption really is.

Even one of the most powerful men in the world eats them. Need we say more?

© S. Loeb/AFP/Getty Images

© S. Loeb/AFP/Getty Images

Actually, I will say three more things: (1) We need a lot more investment in research to quantify the effects of this trade on threatened frog populations, (2) I wonder if Mr. Obama, his chef, or the restaurant owner had any idea what species or what country the frog in question came from?, and (3) if you still think cooked frog legs is a minor epicurean oddity enjoyed only by slightly eccentric French gourmets, think again.

CJA Bradshaw

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Cartoon guide to biodiversity loss II: frog legs

1 02 2009

I couldn’t resist this. Given the enormous response to our soon-to-be-published paper in Conservation Biology entitled Eating frogs to extinction by Warkentin, Bickford, Sodhi & Bradshaw (view post How many frogs do we eat?), I just had to put these up. Enjoy this subclass of biodiversity loss cartoons for what they are worth.

CJA Bradshaw

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How many frogs do we eat?

20 01 2009

IMG_20130209_141200A paper that my colleagues and I wrote soon to appear in Conservation Biology describes the massive worldwide trade in frog parts for human consumption. I bet you had no idea…

This report from New Scientst:

Are frogs being eaten to extinction? We’re used to hearing about how disease, climate change, and habitat degradation are endangering amphibians, but conservationists are warning that frogs could be going the same way as the cod. Gastronomic demand, they report, is depleting regional populations to the point of no return.

David Bickford of the National University of Singapore and colleagues have called for more regulation and monitoring in the global frog meat market in order to avoid species being “eaten to extinction”.

Statistics on imports and exports of frog legs are sparse as few countries keep track of the amount of meat harvested and consumed domestically.

According to UN figures, global trade has increased in the past 20 years. France – not surprisingly – and the US are the two largest importers; with France importing between 2500 and 4000 tonnes of frog meat each year since 1995.

But although frog legs are often thought of in the West as a quintessentially French dish, they are also very popular in Asia.

Bickford estimates that between 180 million to over a billion frogs are harvested each year. “That is based on both sound data and an estimate of local consumption for just Indonesia and China,” he says. “The actual number I suspect is quite a bit larger and my 180 million bare minimum is almost laughably conservative.”
Local depletion

Even top French chefs may be unaware of where their frogs are coming from. Bruno Stril, teaching chef at the Cordon Bleu school in Paris, France, is unsure where his suppliers source their frog legs. “I would like for them to come from France,” he says. But he expects that most of the meat comes from other countries.

Stril is on the right track. Indonesia is the world’s largest exporter of frog meat, exporting more than 5000 tonnes of frog meat each year, mostly to France, Belgium and Luxemburg.

Bickford and colleagues say European kitchens initially found their own supplies in the surrounding countryside, but the fact that they are now importing from Asia suggests local populations were over-harvested. This, they say, could be a sign that frog populations, like many fish populations, will be harvested to near extinction.

“Overexploitation in the seas has caused a chain reaction of fisheries collapses around the world,” the researchers write. “This experience should motivate better management of other exploited wild populations.”
Anonymous legs

James Collins, of the World Conservation Union, says the Californian red-legged frog offers some evidence for the theory. This species was first harvested for food in the 19th-century California gold rush and eventually the population began to crash.

However, Collins cautions that “at the moment we have no data indicating that commercial exploitation has led to the extinction of any amphibian species.” He says the Bickford team’s evidence is worrisome, but inconclusive.

Most harvested frogs are skinned, butchered and frozen before being shipped overseas. This makes it difficult to know exactly what species are being killed. Indonesia is thought to mostly export crab-eating frogs, giant Jana frogs, and American bullfrogs. How much meat is consumed within Indonesia’s borders is also something of a mystery. Some studies suggest it could be between two and seven times what is exported.

“There are a hell of a lot of frogs being eaten,” says Bickford. “Much more than most people have a clue about.”

Original article soon to appear: Warkentin, IG, D Bickford, NS Sodhi, CJA Bradshaw. 2009. Eating frogs into extinction. Conservation Biology DOI: 10.1111/j.1523-1739.2008.01165.x

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Measuring the amphibian meltdown

9 01 2009

melting_frog_by_zarinstar.pngA paper my colleagues and I published earlier last year in the open-access journal PLoS One describes one of the largest databases of amphibian threat risk ever compiled. Our main aims were to determine which factors drive amphibians toward extinction – this being especially topical considering that amphibians epitomise the modern biodiversity crisis: major population declines, disease outbreaks, deformities and recent confirmed extinctions dominate the biodiversity news. 32 % of all amphibians worldwide are threatened with extinction, 43 % of described species are declining, and about 160 species have already gone extinct in the last few decades.

In our paper (Sodhi and colleagues) entitled Measuring the meltdown: drivers of global amphibian extinction and decline, we found that the range size occupied by a species was overwhelmingly the principal driver of threat risk. This means that although other factors are involved, the number one (by far and away) thing threatening amphibians is habitat loss – everything else is minor by comparison.

Of course, we shouldn’t ignore other issues – increasing climate seasonality (temperature and precipitation) also contributed to higher threat risk. This is exactly the sort of thing that is predicted to increase with climate change (more variable weather patterns). In many cases, it’s the variability that’s worse than the mean trend when it comes to biodiversity.

So what should we do? Our results suggest that areas containing high numbers of restricted-range amphibians should have conservation priority. Although captive breeding might help to buffer some declining populations in the short term, such interventions cannot substitute for habitat protection and restoration. The synergies between ecological/life history traits and environmental conditions demonstrate how management must address each of the major drivers of decline together for any success – there is no magic bullet to prevent extinctions. We also recommend that substantial increases in international research on the long-term monitoring of amphibian populations is required to mitigate effectively the current meltdown of amphibian biodiversity.

CJA Bradshaw

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Foiling the frog-killing fungus

15 12 2008

© F. Brem

© F. Brem

Something I picked up the other day that is an interesting application of ecology and engineering – extreme interventions like this may become more and more necessary, especially for particularly vulnerable taxa like amphibians. This one from New Scientist:

A fungal disease is decimating amphibian populations around the world, and so far the only way to save a species at risk is to remove individuals from the wild. Is it time to try taking out the disease as well?

So far the majority of amphibian conservation efforts have focused on identifying species at high risk of extinction, and establishing captive breeding programmes in biosecure units where they will be protected from Batrachochytrium dendrobatidis Bd, the chytrid fungus that is responsible for the devastating scourge.

“The immediate response has been the right one: to get species that are at risk into captivity,” says Trent Garner of the Institute of Zoology in London. However, he adds, “we’re potentially missing out on some very important species” because, inevitably, some are prioritised over others.

Now an alternative strategy is emerging, which many had previously thought impossible: to reduce the amount of Bd in the wild, and perhaps even to enable amphibians to survive alongside it.

In lab experiments, Garner and colleagues have shown that it is possible to cure tadpoles infected with Bd by bathing them in the antifungal drug itraconazole for 5 minutes a day for seven days. “Even using extremely low doses, we showed that you can eliminate Bd from tadpoles,” says Garner, who presented his results at a meeting on amphibian decline at the Zoological Society of London last week.