Illustrated by Perry Shirley

Ocean reserves help with acidification

By John Upton

Our power plants and cars have pumped so much carbon dioxide into the atmosphere that the oceans are becoming more acidic. Something like a quarter of our carbon dioxide pollution dissolves into the seas, where it reacts with water:

CO2 (aq) + H2\leftrightarrow H2CO3 \leftrightarrow HCO3 + H+ \leftrightarrow CO32− + 2 H+

Those leftover hydrogen ions at the right of the equation add up. The hydrogen ion concentration at the surface of the world’s oceans has increased by 26 percent since pre-industrial times, leading to a pH decline of 0.1. That might not sound like much, but it has been enough to kill off billions of farmed shellfish and punch holes in the shells of wild sea snails.

Illustrated by Perry Shirley
Illustrated by Perry Shirley

Shellfish and corals are especially vulnerable to ocean acidification because they rely on calcium carbonate to make their shells and skeletons. Ocean acidification increases concentrations of bicarbonate ions while decreasing concentrations of carbonate ions — and these animals need calcium carbonate to produce their protective body parts.

Fish, meanwhile, are thought to be suffering neurological effects of acidifying oceans, while vast mats of algae are expected to flourish.

The good news is that populations of animals naturally adapt to changes in their environments — and evolutionary changes to help some species cope with ocean acidification are already underway. The bad news is that changes in oceanic pH levels might be happening too quickly for animals to adapt, threatening scores of marine species with extinction.

I asked Ryan Kelly, an assistant professor at the University of Washington’s School of Marine and Environmental Affairs, and a coauthor of a recent BioScience paper about acidification that I wrote about for Pacific Standard, whether we could do anything to help species accelerate the rate with which they evolve needed adaptations.

“‘Accelerating’ species’ evolutionary adaptations to acidification would mean either tweaking the heritability of traits — and it’s unclear whether this is desirable, or how to do it; or increasing the strength of selection — which would mean making the selective impacts of acidification worse than they already are,” Kelly said. “So I’m thinking that, in an evolutionary sense, you don’t want to accelerate adaptation.”

Is there anything that we can do?

“What you do want to do, in order to protect marine ecosystems as we know them, is to preserve the adaptive capacity of the species that make up those ecosystems. That means preserving the genetic diversity that exists within those species, so that when the selective pressures of acidification happen, there will be some variability in those species’ responses. When there’s no genetic diversity, you get no variability in response to selective pressure, and natural selection and evolution doesn’t really work.”

Which means that we need to expand and improve the globe’s network of marine reserves, banning fishing in some places, and giving species the best possible shot of surviving the storm of acidity that’s building around them.

“From a conservation perspective, measures that preserve existing genetic diversity safeguard the adaptive capacity of species and ecosystems. This means working to maintain large population sizes and not fragmenting habitats, which are common conservation measures.”

As U.S. Secretary of State John Kerry led workshops last month dealing with ocean acidification and other ocean health issues, President Barack Obama’s administration proposed sweeping expansions of marine reserves surrounding remote Pacific Ocean atolls. The move would limit fishing for tuna and other species, helping to protect top predators that are critical for ecosystem health, while also protecting smaller species that are killed as bycatch.

“This is an important step in trying to maintain the health of this region and, as a result, the surrounding areas in the Pacific,” said Lance Morgan, president of Marine Conservation Institute. “It will give us more resilience into the future. We’ll have to replicate this and do more work in other areas as well, but it is an important step.”

Meanwhile, the National Oceanic and Atmospheric Administration is planning to expand the boundaries of Gulf of the Farallones National Marine Sanctuary and Cordell Bank National Marine Sanctuary, both of which lie off the West Coast, where strong upwelling leads to especially severe rates of ocean acidification. Meanwhile, Kiribati recently announced that it would close an area the size of California to fishing to help wildlife recover.

Ocean acidification is not a major consideration in the creation of marine reserves, but it’s a growing threat against which the reserves can help populations of wildlife evolve natural defenses.

Illustrated by Perry Shirley.

Why fish need wood

By John Upton

Trees don’t just provide habitat for arboreal and terrestrial creatures — dead trees that have toppled over in shallow waters are critical for aquatic wildlife. Woody habitat in lake littoral zones provides shelter for fish. It also supports the growth of algae and the like, which are eaten by herbivorous fish and other critters.

As the globe warms and as aquifers are sucked dry, lake levels in many parts of the world are falling. And as a lake’s water level drops, semi-submerged trees that ring the lake’s shallows can be left high-and-dry. That can decimate fish populations — harming birds and other species that feed on them.

“Reduced lake levels generally decrease littoral habitat, which is critical to aquatic food webs,” wrote University of Wisconsin researchers in a recent paper published by the Canadian Journal of Fisheries and Aquatic Sciences. “Fishes across all trophic levels are known to rely heavily on littoral food sources, with littoral zones supporting 65% of the consumption by lentic fish communities and 57% of their body carbon.”

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

The scientists sampled fish from 2000 until 2005 and again from 2007 to 2009 in Wisconsin’s Little Rock Lake, which is in the Great Lakes region. Declining water levels in the Great Lakes, which is Earth’s largest body of fresh surface water, are a major worry for scientists.

During the monitoring period, drought led to a decline in water levels of a little more than a meter. That left three quarters of the lake’s woody habitat stranded on land. The following graphs from the paper show the close relationship between water levels and woody habitat:

lake-level

The sampling results painted a picture of an ecosystem in steep decline — a decline that the scientists linked to the loss of soggy wood.

Things got so bad during the drought that the scientists’ minnow traps started to come up empty.

“The rapid decline of the perch population was associated with the loss of available CWH [coarse woody habitat],” the paper states. “Perch first failed to appear in a trapping event in 2005, after only a 10% loss of CWH. No perch were detected in 2008 or 2009 after 58% and 72% of the available CWH had been stranded from the littoral zone.”

The loss of the perch was blamed on the declining water levels, with changed temperature and oxygen levels potentially contributing. A loss of food was also stated as a potential factor. As was the loss of spawning habitat and loss of shelter from predators due to the disappearance of woody habitat.

“Previous research has suggested the potential for predator–prey encounter rates to increase with reduced CWH, which would result in intense bass predation on perch. … [T]he severe depletion of the perch population might have been exacerbated by the relatively high densities of bass in Little Rock South, which initially increased with reduced lake level.”

Eventually, though, the largemouth bass were found to grow more slowly as the lake’s water level fell.

The study’s lead author, Jereme Gaeta, tells Wonk on the Wildlife that the findings have implications for a warming planet.

“Future climate projections are uncertain, but we generally expect evaporation to outpace precipitation in many regions such as northern Wisconsin,” Gaeta said. “Our research shows that loss of littoral habitat can change not only the way fishes interact but also change fish community and food web structure.”

To help protect aquatic communities from the loss of littoral woody habitat, the paper recommends manually placing dead trees in lakes — something scientists call tree drops.

“Potential preventative measures when lake levels drop are limited. Our best options are to protect and restore natural shorelines to ensure future inputs of woody structure are possible and, when water levels begin to drop, add trees to deeper waters or steeper shorelines,” Gaeta said.

Little Rock Lake
This photograph from the paper shows wood stranded above Little Rock Lake’s shoreline as water levels declined.
Illustrated by Perry Shirley.

Heterokaryosis hypothesis: Could it help feed the world?

By John Upton

As scientists have started to figure out what a mycorrhizal fungus really is, they’ve discovered that it might be a really fun guy.

I mean, ahem. They’ve discovered that it might really be fungi.

Genetic sequencing is revealing surprising secrets of arbuscular mycorrhizae. The discoveries are casting doubt on notions of fungal individuality and offering new ways of boosting the amount of food that’s grown the world over.

Mycorrhizal fungi, aka myco, are soil dwellers that forage for water and nutrients, which they exchange for sugars produced by photsynthesizing plants. As I explained recently in Grist, they cool the globe and boost crop yields.

Research during the past decade suggests that what many of us would assume was a single myco fungus might actually be lots of mini fungi bits — genetically diverse nuclei that live and work together inside what we would logically perceive to be a fungus. There, the nuclei collaborate to create long mycelia and hyphae that stretch from root to root, delivering water and nutrients up to the plants, and passing carbon from the plants down into the soil.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

This proposed blend of different nuclei is called the heterokaryosis hypothesis (a heterokaryon is a cell containing genetically diverse nuclei) — and it’s highly controversial. A recently flurry of papers has concluded that it is flat-out wrong, but those findings have been criticized by scientists who subscribe to the hypothesis.

If correct, the hypothesis could help scientists solve a couple of longtime fungal mysteries.

For one thing, it could help explain how and why mycelia from seemingly different fungi fuse together as they snake through the soil.

It could also explain how these types of fungi reproduce. Molecular evidence tells us that the fungi exchange genes, which suggests that they are mating. But scientists have never been able to figure out quite how they’re doing it. The heterokaryosis hypothesis suggests it’s the nuclei within each fungus that are breeding. It appears that they are migrating through fusions between the hollow mycelia.

“Why this heterokaryosis thing is so important,” said Ian Sanders, a professor of evolutionary biology at the University of Lausanne, “is because — I believe — we can use these genetic differences among the nuclei to create fungi that make plants grow better.”

Sanders has been involved with research in Colombia, where fungi have been developed that boosted cassava yields by one fifth while requiring less fertilizer. The research program is being expanded to Africa, where cassava, a root vegetable similar to a potato, is a dietary staple.

The breakthroughs relied on breeding techniques that took advantage of fungal heterokaryosis. More such breakthroughs would mean bigger yields of crops, more food, and less world hunger.

(Speaking of food, it’s worth noting that the heterokaryosis theory has nothing to do with mushrooms. There are two main types of mycorrhizae. Endomycorrhizae, which are the subject of this article, are arbuscular. They pierce the roots of plants with tiny vesicles and arbuscules, which are microscopic organs that helped both kingdoms of life adapt to life on land some 460 million years ago. It is the other type of mycorrhizae, ectomycorrhizae, the less common and less ancient union that engulfs roots without penetrating them, that produces mushrooms.)

Endomycorrhizae fungi infuse the roots of nine out of ten crop varieties, yet we know precious little about them. That’s largely because of complications inherent in trying to study an organism that’s intricately woven into the body of another; the result of nearly a half billion years of interdependent evolution.

The heterokaryosis hypothesis has its detractors. They point to research, such as this paper published this month in PLOS Genetics, in which nuclei sampled from a single fungus were nearly genetically identical. Supporters of the hypothesis point to findings from other research where vast genetic diversity appears to have been discovered. Sample sizes in some of the experiments have been very low, and just a few strains have been analyzed, making all of the results highly contentious.

One believer in the hypothesis is Toby Kiers, a mycological researcher at Vrije Universiteit Amsterdam. “It’s a neat concept, because even within an individual you’ve got individuals,” she said.

Kiers will begin lab experiments next month designed to help breed mycorrhizal strains that further boost crop yields. I highlighted the planned research in a recent magazine article about myco fungus in The Ascender:

[Kiers] has secured funding to watch mycelia squeeze through tiny mazes, peering at them through microscopes as they trade nutrients with plants for sugars under different conditions. The goal, she says, is to “study their decision-making skills.”

Kiers’s research will combine cutting-edge microscopy and mycology with old-fashioned breeding techniques in a bid to select the most useful fungal strains. “They’re quite easy to select on,” she said, “because there’s so much genetic variability — even within a single hyphae, within a single spore.”

Illustrated by Perry Shirley.

Global warming is changing how caterpillars eat

By John Upton

Animals can evolve to survive global warming by changing their behavior and by changing their bodies. Butterflies are particularly sensitive to climate change, and changes in their behavior have been well documented – most notably in their migration patterns and ranges. North American Butterfly Association president Jeffrey Glassberg recently told the Maryland Independent that climate change is affecting Rhopalocera on a vast scale. “There’s a whole suite of butterflies whose ranges are retreating,” he said. (Such changes are the subject of Flight Behavior, a novel by Barbara Kingsolver dealing with climate change.)

And now comes the first evidence that butterfly larvae are changing the internal workings of their bodies to help them cope with warming temperatures.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

University of North Carolina scientists studied the optimal feeding temperatures of Colias spp. caterpillars from California’s Sacramento Valley and Colorado’s Montrose Valley. The frequency of very hot days and nights at both sample sites have increased since the 1970s, when a similar study with the same caterpillar populations was conducted. Caterpillars feed best within specific temperature ranges, and the researchers discovered that the caterpillars have evolved to feed at higher temperatures. The results of the study were published in the journal Functional Ecology:

This study is among the first to show population changes in physiological performance in response to recent climate change, although previous theoretical work has predicted such changes. While previous work has highlighted adaptation to seasonal timing, specifically photoperiodic cues, our work suggests that rapid adaptation to changing thermal regimes may also be an essential mechanism.

I asked lead researcher Jessica Higgins whether she thinks that butterflies are among the first organisms to adapt their physiologies to warming conditions — or whether she thinks this was just the first time that such changes have been detected by scientists.

“I do think that other organisms may be adapting, but we can’t detect it because of the lack of good historical data,” Higgins said. “What made my experiment so unique was that I had this snapshot of caterpillar physiology back in the 1970s. I was able to compare my results with what they previously found and then correlate it with temperature. I think my study highlights that there can be adaption to physiological traits — not just changes in seasonality, which has been the main focus of previous adaptation-to-climate studies. “

Illustrated by Perry Shirley.

Western Australia to use “archaic” method to cull sharks

By John Upton

Great white sharks are among Earth’s most formidable predators. They are apex predators. They prey on fish, mammals and birds — but nothing preys on them.

Except humans.

And in Western Australia, the state government, tired of losing surfers and other beach-goers to the toothy jaws of these ferocious elasmobranchs, has become a predator.

“The preservation of human life is our number one priority,” said Troy Buswell, the state’s fisheries minister, in announcing new policies that will see white sharks killed if they venture within a kilometer of popular beaches. The state’s decision to cull sharks has sparked a global controversy, and polling suggests that even West Australians are overwhelmingly opposed.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

“The decision by Western Australia officials to cull sharks off the coast is alarming,” said Ashley Blacow, a policy and communications official with nonprofit Oceana. “Sharks play a critical role in keeping ocean ecosystems healthy. The presence of sharks ultimately increases species stability and diversity of the overall ecosystem. White sharks in particular are a vulnerable species and they should be protected, not killed.”

One of Western Australia’s most controversial approaches to culling sharks will see floating drums placed around beaches, attached to baited hooks. The trapping equipment are known as “drum lines” — and conservationists regard them as appallingly cruel. Drum lines are illegal in many parts of the world, including in the U.S. One shark expert described the killing method as “archaic” in an interview with Nature.

“Drum lines are 55-gallon steel drums with heavy tackle-like chains or large lines connected to bait,” David McGuire, director of Shark Stewards, told us. “They’re usually anchored to the bottom or they can be linked in chains. I’ve seen them used illegally in Mexico to catch sharks. Essentially, the shark bites the bait, is hooked, and drowns.”

Perhaps most troublingly, there is a lack of scientific evidence that such culling actually protects humans from shark attacks. It might feel satisfying to kill a member of a species that has been killing humans, but that sense of satisfaction might be more of the revenge variety than anything else. Hawaii culled nearly 5,000 sharks between 1959 to 1976, yet there was no change in the rate at which sharks attacked humans in those same waters.

Unfortunately, it may take years of shark culling and shark attacks before the West Australian government can determine whether its new policies are having the effect that it desires.

“True effectiveness cannot be assessed by simply counting the number of sharks captured and killed,” writes University of Hawaii researcher Carl Mayer in an article published by The Conversation. “Demonstrable effectiveness means a measurable decrease in shark bite incidents in response to culling activities.”

Illustrated by Perry Shirley.

Bambi should have been shot and killed, science says

By John Upton

Is it better to kill an orphaned fawn, or is it better to leave it alive, left to try to survive alone in a menacing world?

That unpalatable question is not a hypothetical one in Scotland, where some 60,000 red deer are culled every year — part of an effort to keep populations down to protect crops and woodlands from the hungry grazers.

And Scottish policy is clear on what the answer should be after a hunter orphans a fawn: Kill the baby.

“Shoot both female and juvenile where-ever possible,” the guidelines state. “Where possible target calves first and maintain vigilance for orphaned calves. ”

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

Josephine Pemberton, a professor at the Institute of Evolutionary Biology, University of Edinburgh, wanted to know whether that policy was scientifically wise. Using funding from the U.K. National Environmental Research Council, Pemberton and five other scientists analyzed data from censuses of a red deer population on Scotland’s Isle of Rum dating back to the 1970s.

What they found was that depriving a deer of its mother’s care and protection before its second birthday triggered resounding impacts. Orphaned males and females were more likely to grow haggard and die young. Males were hit particularly hard — and male orphans had trouble growing antlers as they matured, reducing their chances of winning mates and reproducing. As for female fecundity? “Although we failed to find evidence that female orphans paid a reproductive cost,” the scientists wrote in their paper, which was published in August in the journal Behavioral Ecology and Sociobiology, “we cannot discount an effect on female physical condition.”

Pemberton said the results show that young deer should be killed if they are orphaned by a hunter — even if they are old enough to not seem helpless.

“If anything, our results suggest that if a young animal is still going around with its mother in its second year — and they often do — you should try and shoot it then, too,” Pemberton said.

But that’s easier said than done. And not just because shooting a fawn must surely be a heartrending task for even a hardened stalker.

“Although culling calves with their mothers is in the best practice guidance, stalking is a tough job done largely alone,” Pemberton said. “Stalkers are often under pressure to shoot a lot of hinds. Shooting the pair takes time and effort and we know they don’t always manage to do it.”

yellow pages wide

Why don’t we measure biodiversity?

By John Upton

Vast resources are plowed into measuring the metrics associated with global warming. Calculations reveal that American and European greenhouse gas emissions are falling while China’s are rising, and that more carbon dioxide is being pumped out worldwide every year than had been the case the year before. We know that carbon dioxide levels passed a record-breaking 400 parts-per-million point in May, well above the preindustrial level of 280 ppm, before dipping in line with normal seasonal fluctuations — that knowledge is courtesy of air monitoring in Hawaii and the findings of ice-core studies. And gravity-measuring satellites are used to estimate the rate at which glaciers are melting — revealing that despite harboring just 1 percent of the world’s land ice, these thawing rivers of ice are responsible for 29 percent of the rise of sea levels.

The results of these measurements don’t just keep us awake at night. They help policy-makers target efforts to reduce emissions and to prepare communities for changes in the climate.

But what about biodiversity?

Although the world is rallying around efforts to come to terms with its climate problem (even if not enough is being done to actually solve that problem), it is failing to measure the alarming decline of biodiversity, which by one recent estimate has fallen 30 percent in 40 years. It is not investing the resources needed to track the genetic stockpile contained in the cells of plants, animals, mushrooms and other forms of life as forests are bulldozed, rivers are diverted and acidifying oceans are overfished.

Every time a species or a jungle is lost, and every time environmental tumult helps generalists (such as ring-billed gulls) outcompete specialists (such as piping plovers), the world loses some of its genetic code. That code is critically important. It can help an ecosystem weather changes in the, well, in the weather, which is happening now more than ever in human history. It can help sustain a myriad of complex food chains that underpin the very functioning of the natural world. And it can present humans with chemical compounds that prove useful as new drugs or foods.

If we are to get a handle on the specifics of the biodiversity crisis, which we must do if we are to effectively manage the problem, then more scientists need to be trained and employed and provided with the resources needed to advance their fields.

Aware of the problem of falling biodiversity, the United Nations last year formed the Intergovernmental Platform on Biodiversity and Ecosystem Service. The group is structured a bit like the Intergovernmental Panel on Climate Changeits primary function is to review, assess, synthesize and share information about biodiversity with policy makers.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

The group held meetings in Malaysia this week to discuss two main topics: the measurement and assessment of genetic and biological resources; and the calculation of the value of key ecosystem services.

The conclusion: The world just isn’t doing enough to measure biodiversity.

“Of the estimated 10.8 million species on land and in the oceans, less than 2 million have been scientifically described,” IPBES chairman Zakri Abdul Hamid, science advisor to Malaysia’s prime minister, said in a statement published Wednesday at the end of the three days of talks. “If we don’t know what species there are out there, we don’t know what niche they fill in a healthy ecosystem or perhaps in remedying some human condition.” More from the statement:

Most world nations – unanimously committed to protecting biodiversity – nevertheless cannot measure and assess their genetic and biological resources, nor the value of key ecosystem services nature provides to them, international experts from 72 countries warned today.

In addition to taxonomists, nations lack economists able to put a value on the water purification, storm protection and other services of nature, which would inform trade-off choices in development planning. And fewer still deploy social scientists to estimate nature’s non-economic (e.g. cultural) values, or to find ways to effect needed changes in human attitudes and behaviour.

“There’s an old saying: We measure what we treasure. Unfortunately, though we profess to treasure biodiversity, most nations have yet to devote adequate resources to properly measure and assess it along with the value of ecosystem services,” Zakri said. “Correcting that is a priority assignment from the world community to IPBES.”

Illustrated by Perry Shirley.

Human infections are dead ends for valley fever fungus

By John Upton

People infected with two closely-related species of fungi are dying in growing numbers in the American southwest. The Coccidioides spores are blown with dust into lungs, where they can trigger a painful and sometimes-deadly condition known as valley fever.

But any cocci that ends up in a human has hit a dead end. It will not reproduce to spawn a new generation.

That’s because of the lifecycle adopted by these varieties of cocci after evolving with the rodents that share their desert home. The coccis’ ancient ancestors lived and dined on plants. Then they evolved to feast instead on the rotting flesh of dead animals. Now they have evolved to live inside a living mammal, sometimes waiting for years for the host to die so they can pounce and quickly consume the fresh kill.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

Mammals whose immune systems can’t control the fungus may die quickly. But as I explain in Vice’s Motherboard blog, most animals that are infected with cocci develop few symptoms — and those symptoms are normally short-lived:

Normally, [the Cocci] eek out lives as filaments called hyphae. The hyphae live in the soil and produce spores, a lucky few of which get sniffed into the lungs of desert rodents. The spores balloon in size inside the host, forming spherules. The mammal immune system kicks quickly into gear at this point, building walls around the spherules, containing them and developing immunity against further attacks.

It’s when the immune system fails to contain these spherules that the fungus can propagate throughout its victim, sometimes with deadly consequences. As an infected rodent dies, collapsing into the desert, the cocci burst out of suspended animation and unleash streamers of hyphae that eat the rotting meat. As the fungus feasts, hyphae and spores slip back into the soil, ready to start the cycle all over again.

Humans don’t slip into the desert sands when we die. We are embalmed or cremated, making any infection a waste of time for the fungus and, in some cases, a waste of life for humanity. “If a cocci spore gets into a human, it has made a big mistake,” John Taylor, a University of California at Berkeley mycologist, told me. “It’s unlikely to ever become adapted to living in humans.”

Black-backed woodpeckers would face extinction without wildfires

By John Upton

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

This summer has been a tinder-dry scorcher in the American West, where climate change is being blamed for a horror fire season. Mountain snow is melting earlier nowadays and summers are getting hotter — and that perilous partnership is fueling a steady surge in the frequency and size of the region’s wildfires.

The infernos kill firefighters, destroy homes and damage public infrastructure.

But it’s worth remembering that fires are healthy and regenerative phenomena in many ecosystems — including those in the West.

Blazes clear out water-hogging undergrowth and provide blank slates upon which timberlands can grow anew, boosting forest biodiversity. Rugged pods that encase the seeds of some specialized plants open after fire, sowing the genesis of the next generation in fertile fields wiped clean of competitors.

It’s not just plants that have evolved to rely on fire. Woodpeckers, for example, can flourish in its wake. The black-backed woodpecker has a particularly specialized diet that leaves it dependent upon the charred aftermath of wildfires. The species feasts on the wood-boring beetles that proliferate in burned trees following blazes in Western American mountain-ranges.

Rim Fire
The aftermath of the Rim Fire, the fourth-largest wildfire in Californian history, photographed near Yosemite National Park in early September by San Francisco journalist Chris Roberts.

But us humans are not as fond of fire as are the beetles or the woodpeckers that hunt them. Public policy dictates that fires should be avoided and, if that fails, confronted without compromise. The practice of preemptively thinning out forests to reduce fire impacts, and the logging of forests after they burn, have both taken heavy tolls on the black-backed woodpeckers.

Populations of these birds have been harmed so severely by public policies of wildfire suppression that the federal government is reviewing whether genetically distinct populations in two regions should be added to its list of endangered species.

“This is the first time in the history of the Endangered Species Act that the government has initiated steps to protect a wildlife species that depends upon stands of fire-killed trees,” Chad Hanson, an ecologist with Earth Island Institute, said when the U.S. Fish & Wildlife Service announced the review in June.

A clean-up following the Rim Fire, making it more difficult for black-backed woodpeckers to inhabit this area. Photo by Mike McMillan of the U.S. Forest Service.
A clean-up following the Rim Fire, making it more difficult for black-backed woodpeckers to inhabit this area. Photo by Mike McMillan of the U.S. Forest Service.

Hanson coauthored research published in May in The Open Forest Science Journal that showed just how severely one of those two populations of woodpeckers, which lives in the Sierra Nevada and southern Cascade ranges of California and Oregon, has been affected by humanity’s wont to battle fire. Hanson and his colleague, Dennis Odion, obtained data from the government and from their own observations which they used to model the effects of typical wildfire suppression policies in the Sierra on the species’ habitat.

“A scenario based on thinning 20 percent of mature forests over a 20-year period, and post-fire logging in 33 percent of potential habitat created by fire, reduced the amount of primary habitat after 27 years to 30 percent of the amount that would occur without these treatments,” the scientists wrote in the paper.

“Our results indicate that conserving the distinct population of black-backed woodpeckers in the southern Cascades and Sierra Nevada and the biodiversity for which they are an indicator will require that more unthinned area be burned by wildfires and protected after fire as critical habitat.”

The following table was lifted from the paper. It compares the amount of black-backed woodpecker habitat available within a study area following 27 years of simulated fire suppression policies:

woodpeckers and fire

And this photograph of an acorn placed in the trunk of a Rim Fire-charred pine is an endearing reminder that wildlife perseveres following fire. Wild Equity Institute founder Brent Plater tells me it might have been put there by a squirrel or a scrub jay — but that it was most likely the handiwork of an acorn woodpecker. “Caching acorns in tree cavities is what they do for a living,” he said.

Photo by Chris Roberts
Photo by Chris Roberts
Illustrated by Perry Shirley.

These chicks puke at predators

By John Upton

When Eurasian rollers forage for insect prey for their young, they’re not just on a quest for nourishing fat and protein. They’re fossicking through an ecological armory for chemical weapons.

Some plants produce toxins to deter herbivores. Some insects that eat those plants use those plant toxins for their own defense. Eurasian roller chicks use the plant toxins from those insects to produce a pungent orange liquid — an unsavory concoction that scientists have concluded is used as a defense against predators.

A team of Spanish researchers found that Eurasian roller nestlings vomited when they picked them up, but not when they approached the young birds, talked to them or gently prodded them. “This fact suggests that the vomit might be produced in response to some kind of predators that actively grasp and move prey during the predation event such as snakes, rats and mustelids, which are common predators of hole-nesting species as rollers,” the scientists wrote in a paper published in the journal PLOS ONE.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

The researchers collected the puke and smeared some of it on pieces of chicken, which they offered (with the smeared side hidden) to 25 dogs alongside a similar chunk of poultry smeared only with water. Some of the mutts strangely showed no appetite for chicken whatsoever. But 18 of the 20 dogs with a hankering for hen opted first for the untreated meat, indicating that the smell is off-putting for a predator. Most of those 18 dogs subsequently wolfed down the vomit-smeared chicken, but six of them left it entirely alone.

“One could wonder about the nestling advantage of this defence,” the scientists wrote. “Kin selection is a possible answer to that question because a predator that finds the first nestling of a brood of five to be distasteful may leave alive the others.”

From where do the chicks get the hydroxybenzoic and hydroxycinnamic acids, phenolic acids and psoralen needed to produce their unpalatable puke?

The scientists matched these compounds to toxins produced by plants to deter animals from feeding on them. Many insects have developed an immunity to such toxins, and some use the plants’ toxins to defend themselves. That’s the case for many of the grasshoppers upon which the rollers prey, and the scientists believe that the chicks are, in turn, purloining the poisons from the grasshoppers to defend themselves.

But that’s not all — the scientists think that the parent birds might also be hunting for more-poisonous insects, such as centipedes, that most other birds would never touch.

“Grasshoppers are the main prey that rollers hunt to feed their nestlings,” they wrote. “Furthermore, rollers feed their offspring with a large share of poisonous arthropods that are avoided by most of the other sympatric insectivorous birds. This suggests that rollers are resistant to these toxic substances and could have the ability to sequester chemicals from their protected prey to defend themselves.”

An adult Eurasian roller.
An adult Eurasian roller in Kazakhstan. Photo by Ken and Nyetta.

Illustrated ecology news.