bilby

Easter Bilby protects Australia’s outback

By John Upton

Some Australian kids don’t believe in the Easter Bunny.

The clutches of chocolate and colored eggs hidden in the yards and living rooms of environmentally-aware households Down Under are deposited, through orifice unknown, by the Easter Bilby.

Browse the easter sweets selection in just about any Australian store right now and you’ll find foil-wrapped chocolate icons of the adorable outback-dwelling marsupials.

Rabbits are ravenous, fast-breeding, and destructive pests in Australia, where they were introduced by hunters and graziers during the 19th Century. The bare rabbit-resembling bilby, on the other hand, is a native Australian species that’s vulnerable to extinction. Celebrating the Easter Bilby helps Australian kids learn about the ecological importance of native mammals — while avoiding the awkward passions for invasive counterparts that the Easter Bunny can imbue.

bilby

Illustrated by Perry Shirley.

The beauty of the bilby lies in its relationship with Australia’s fragile, old, and nutrient-poor land. It digs through arid and semi-arid soils, bioturbing them, improving water drainage and reducing flooding and erosion. The digging helps spread seeds. It creates microhabitats for bugs and fungi. It turns over soils and helps with nutrient cycling.

From the Mammal Review paper by P. A. Fleming et al.

Mammal Review

The effect of native Australian diggers, such as bilbies, echidnas, and wombats, is “increased plant vigour and resilience, increased biodiversity and consequently improved ecosystem functioning,” scientists wrote in a Mammal Review paper published last year.

But Australian ecosystems have been ravaged during the past two centuries by introduced species, including rabbits, pigs, and camels, and by land clearing. The native diggers are hunted by introduced cats and dogs. Those pressures have helped push half of the nation’s digging mammals toward extinction, the researchers concluded following an exhaustive review of scientific literature. “[T]he loss of digging mammals has contributed to the deterioration of ecosystems,” they wrote.

Rabbits dig as well — but they apparently do not dig deep enough to produce the same benefits as bilbies. Previous research has shown that digging bilbies foster 80 percent more seedlings than do digging rabbits.

“When bilbies, bandicoots, and bettongs dig for food, their diggings are deep, roughly-conical pits which penetrate deep into the soil layers,” Murdoch University wildlife biologist Trish Fleming, one of the coauthors of the Mammal Review paper, told Wonk on the Wildlife.

“Rabbits dig shallower pits, which disturb a large area of the top soil layers. This would expose the soil to drying out, which means it’s less suitable for soil microorganisms or for new seeds.”

Then there’s the wee issue of rabbit plagues. Looking out across an affected Australian farm, the land can appear as if it is moving.

“Rabbits feed on soft shoots of plants, and then will dig up any vegetation within reach, including the roots and bark off trees.  In plague numbers, they wipe out any living plant material.  There are expanses of productive lands which have never recovered from plagues of rabbits,” Fleming said.

So go and get stuffed with caramel, Easter Rabbit. Aussies don’t need your type sniffing about in their gardens.

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.

Little brown bat

Research: Bat-killing fungus arrived from afar

By John Upton

A ripple of bat deaths has grown since 2006 to become millions of Chiroptera deep, stretching out from its New York epicenter into five Canadian provinces and west at least as far as Missouri. The latest state to be affected was Minnesota, where infected bats were discovered in two parks.

The dead bats were all members of species that hibernate — and they succumbed to white nose syndrome. The disease is caused by a fungus that eats away at their wings and faces.

Little brown bats are among the worst affected. These adorably tiny bats were common throughout Eastern America as little as a decade ago, sucking down mosquitoes and other pests during their nocturnal maunders. Now the species appears to be on the verge of being listed as federally endangered.

Illustrated by Perry Shirley.

Illustrated by Perry Shirley.

Mammals appear to have developed high body temperatures to help stave off infections of fungi. But hibernating bats have a chink in that armor: When they hibernate, their body temperatures plummet. And when most bats hibernate, they huddle together, which helps the fungal infection spread through the slumbering colony.

What caused this fast-moving fungus to suddenly begin attacking bats? Did it go rogue, evolving from a soil eater into a devourer of bat flesh? Or is it an invasive species that arrived from some far-flung place?

A pair of Wisconsin-based U.S. Forest Service scientists studied the DNA of the disease along with that of more than a dozen species of other fungi found growing in bat caves in the eastern U.S. What they found, first and foremost, was that the pathogen was not quite what everybody thought it was.

Scientists have called the disease Geomycetes destructans since it was identified in 2009. But the recent research, described in the journal Fungal Biology, indicates that the fungus is actually a member of the genus Pseudogymnoascus. Hence, it has been reclassified P. destructans.

Of the other species of Pseudogymnoascus fungi sampled in the studied hibernacula, the scientists reported that none were closely related to P. destructans. That’s significant, because it suggests that white-nose syndrome arrived in New York from some other part of the world, perhaps on the shoes of a traveler or shipped in as a few spores with freight.

Researcher Andrew Minnis said the study is part of a wider effort to find a way to protect bats from the fungus. “Once key elements of this [fungus] species’ biology, including mechanisms of pathogenicity, are identified, it will be possible to target them,” he said.

Once it was realized that many related fungi were present in bat caves, but weren’t killing bats, “thoughts arose that these species could be used for comparative purposes — to understand why P. destructans is different,” he said. Following the findings from this study, “further and more informed comparative work can now be performed.”

Confirmed and suspected white-nose syndrome cases. Map updated August, 2013 by the U.S. government.

Confirmed and suspected white-nose syndrome cases. Map updated August, 2013 by the U.S. government.

Illustrated by Perry Shirley.

Dutch gulls eat their young on Sundays

By John Upton

The durations of days and years are calibrated by celestial turntables: The spinning of the Earth and its arcing around the sun. Humans and wildlife alike live out rituals according to daily and annual schedules.

But the seven-day week is a human construct. It’s an arbitrary chunk of time that cocoons timetables of work and rest, of television programming and soccer practice. Whenever you see wildlife falling into a weekly routine, you can be confident it’s the result of a human influence.

A weekly schedule plays out among European herring gulls and lesser black-backed gulls nesting in the dunes of the Dutch island of Texel. And it’s a macabre one.

Illustrated by Perry Shirley.

Illustrated by Perry Shirley.

A chick being reared in these dunes may dread Sunday more than a young atheist dreads their mandatory church outings. It’s on Sundays that adult gulls are most likely to cannibalize the young. Saturdays are also popular chick-eating days among the Texel gulls, though not to the same extent as is the case on Sundays.

Sometimes the gulls eat their own chicks — or their own eggs. But more often they steal the unattended young of other birds, in some instances to be shared with their own hungry broods.

That’s not the only weekly pattern that marine ornithologist Kees Camphuysen has discovered during his studies on the island. Chicks tend to grow in spurts during the week, then their growth slows down over the weekends.

The Royal Netherlands Institute for Sea Research scientist thinks he knows what’s going on. He contends that it’s the weekly patterns of the region’s beamtrawlers and shrimpers that are driving the hebdomadal trends.

“[A] very strong weekly pattern in fleet size occurred, with high numbers of boats at sea Monday through Thursday, a much reduced number (mostly homeward bound) on Friday, and near to nothing on Saturdays and Sundays,” he wrote in his Ph.D. thesis.

The Texel Dunes gulls feast on the by-caught scraps of the fishing fleet, trailing the boats to scavenge protein for themselves and for their growing chicks. But when this supply of human surplus dries up over the weekends, the chicks’ growth rates slow, and hunger can drive the birds to cannibalism.

“Only commercial fisheries have a periodicity that can explain the strong, cyclic synchronisation in chick growth,” Camphuysen wrote. “Chick cannibalism rates were a mirror image of the rhythmic cycle in growth increments.”

The following series of photographs was published in Camphuysen’s Ph.D. thesis, showing an attack on an unattended chick by a bird from a nearby nest. The attacking gull can be seen sharing the kill with its own chick. If you would prefer to not see an adorable lesser black-backed gull chick being pecked to death and gutted by its own kind, then stop scrolling now.

cannibal-gull-in-action

Illustrated ecology news.