I was at the Ecological Society of America’s Annual Meeting when I saw this tweet:
For those of you who are wondering how you weaponise shark teeth, which are already regenerating, serrated meat knives at the business end of a streamlined, electric-sensing torpedo, here’s how. You drill a tiny hole in them, and then bind them in long rows to a piece of wood to make a sword. Or a trident. Or a four-metre-long lance. And then, presumably, you hit people really hard with them.
That’s what the people of the Gilbert Islands have been doing for centuries. Sharks are an ingrained part of their culture and their teeth have been an ingrained part of their weapons. Tiger sharks feature heavily – they have thick, cleaver-like teeth that can slice through turtle shells so they make a good cutting edge. But the weapons also include the teeth from spottail, dusky and bignose sharks (you can identify species from their teeth), and none of these actually live around the Gilbert Islands today.
Drew, who studied 124 of these weapons, says that their teeth reveal a “shadow diversity” – traces of sharks that disappeared from the surrounding waters before we even knew they were there. I wrote about this story for Nature News – head over there for the full details.
When Rachel Carson wrote her famous book Silent Spring, she envisioned a world in which chemical pollutants killed off wildlife, to the extent that singing birds could no longer be heard. Pesticides aside, we now know that humans have challenged birds with another type of pollution, which also threatens to silence their beautiful songs – noise.
A man-made world is a loud one. Between the din of cities and the commotion of traffic, we flood our surroundings with a chronic barrage of sound. This is bad news for songbirds. We know that human noise is a problem for them because some species go to great lengths to make themselves heard, from changing their pitch (great tits) to singing at odd hours (robins) to just belting their notes out (nightingales). We also know that some birds produce fewer chicks in areas affected by traffic noise.
Now, Julia Schroeder from the University of Sheffield has found one reason for this. She has shown that loud noises mask the communication between house sparrow mothers and their chicks, including the calls that the youngsters use to beg for food. Surrounded by sound, the chicks eat poorly. “City noise has the potential to turn sparrow females into bad mothers,” says Schroeder.
The image above, which may be the worst photo of a Californian condor ever taken, was the best shot I snapped during a four-hour condor-watching trip in 2010. But even this grainy image is important, for it captures one of the 405 last Californian condors in the world.
Myra Finkelstein from the University of California, Santa Cruz writes that the condor is “a symbol of environmental tragedy and triumph”. The huge bird, with its three-metre wingspan and eerily smooth flight, was once widespread across North America. Between power lines, guns, and pesticides, their population plummeted. The birds were frequently poisoned by lead after scavenging off shot-filled carcasses, and that’s if poachers weren’t filling them with lead shot in a more direct way.
By 1982, there were just 22 Californian condors left in the world, and all of them were in captivity. An intense captive breeding programme began, and it has been an apparent success. There are currently around 400 birds, more than half of which fly free and wild.
But this might be a pyrrhic victory. Finkelstein has now shown that the condor’s fate is far from certain. Even though we have brought it back from the cusp of extinction, its old enemy – lead – is still a major threat. If conservation efforts are scaled back, the condor will disappear once more unless the use of lead-based ammo is severely or completely curtailed. Read More
Australians love to destroy cane toads. Ever since these animals were first introduced in 1935, they have run amok, eating local animals and poisoning any that try to eat them. They’re captured and slaughtered in traps, bludgeoned with golf clubs, and squished with veering tyres, but still they continue to spread. Now, Michael Crossland from the University of Sydney has discovered an unlikely ally in the quest to control the cane toad: the cane toad.
Along with their unappealing appearance and milky poison, cane toads are also cannibals. Older tadpoles will hunt and eat eggs that have been recently laid in the same pond, to do away with future competitors. Crossland reasoned that the eggs must release a substance that the tadpoles can detect, so he mushed them up in his lab and separated out their chemical components.
He discovered that the eggs secrete bufadienolides – the same substances that make the milky poisons of the adult toads so deadly to Australia’s fauna. Ironically, the same chemicals that protect the eggs later in life also attract cannibalistic tadpoles. And that makes them excellent bait.
Imagine a world of two dimensions, a world with no up or down… just across. No climbing, falling, jumping, or ducking… just shimmying and sidling. Welcome to the world of the sea skater.
Sea skaters, or ocean striders, are small bugs. They’re relatives of the pond skaters or water striders that zip spread-eagled across the surface of ponds and lakes. Except they skate over the open ocean, eating plankton at the surface. “They skate through storms and wind and waves,” says Miriam Goldstein from the University of California San Diego and the Deep Sea News blog. “They even have a little ‘life jacket’ – the hairs on their body trap air so if they get sunk by a wave, they pop back up. They’re amazing!”
There are only five species of sea skaters, all belonging to the Halobates group. Of all the millions of insect species, these five are the only ones to live out at sea. Now, Goldstein has discovered that one sea skater Halobates sericeus actually benefits from what most people would regard as an ecological disaster – the circling mass of plastic and debris known as the Great Pacific Garbage Patch.
Since 1928, thousands of chimney swifts have roosted at Fleming Hall, a university building in Kingston, Ontario. For decades, they fed on local insects, and excreted the remains down one of the building’s chimneys. Around 2 centimetres of droppings, or ‘guano’, built up every year until the chimney was finally capped in 1992. To this date, Fleming Hall contains a hardened guano tower, two metres tall and 64 years in the making, which preserves a layered record of the swifts’ meals.
Now, a team of scientists, led by Joseph Nocera, have used this archive of historical poo to explain why the swift populations have fallen by 90 per cent since their heyday.
In Australia, an ancient murder mystery is coming to a riveting conclusion, thanks to an unusual clue – not a fingerprint, or a bloody weapon, but fungal spores preserved in fossilised dung. The spores belong to Sporormiella, a fungus that only grows in mammal and bird droppings. Large plant-eaters provide it with vast banquets. In turn, the fungus reveals how many big vegetarians were living in the neighbourhood.
Scientists have used these spores to study the deaths of the giant animals that once grazed North America – “megafauna” such as mammoths, woolly rhinos, and more. Now, it’s Australia’s turn. By using Sporormiella records, along with other buried clues, Susan Rule from the Australian National University has found strong evidence that acquits a changing climate in the death of Australia’s giants. Instead, her study points the finger squarely at humans.
Last September, I travelled to Peru to meet a fascinating scientist who is mapping the Amazon by plane. The piece was published in Wired UK earlier this year, and I’m reprinting it here now. This was one of the most enjoyably things I got to write last year. I hope you enjoy it too
A small, twin-propeller plane flies over the Amazon rainforest in eastern Peru. The scale of the vegetation is extraordinary. The tree canopy stretches as far as the eye can see — an endless array of broccoli florets bounded only by haze and horizon. Greg Asner, 43, has seen the rainforest from this vantage point many times before, but he still stares out of the window in rapt fascination.
This patch of forest in the Tambopata National Reserve is rich with life, even by the Amazon’s standards. A 50-hectare patch of forest — the size of as many rugby pitches — contains more plant species than the whole of North America. “We might as well be exploring Mars,” says Asner. “These are areas where no human has ever been. There’s no access.”
Access isn’t a problem for Asner. Behind him are three state-of-the-art sensors of his own devising which, as the plane flies along, take the forest’s measure. “We’re trying to do something really new,” He says. “This world is changing and it requires science that isn’t incremental.” Using the technology he’s developed, Asner is mapping the shape and size of the trees, down to individual branches, from two kilometres above. He can measure the carbon stored in trunks, leaves and soil. He can even identify individual plant species based on the chemicals they contain. With wings and lasers, Asner is conducting one of the most ambitious ecology studies ever staged. He accumulates more data in a single hour than most ecologists glean in a lifetime. With this data, he aims to influence governments, steer the course of climate-change treaties and save the forests over which he soars.
Vultures have among the sharpest eyes of any animal.
Vultures are among the birds most likely to crash into wind turbines and power lines.
If their eyes can spot a tiny carcass from high up in the air, why can’t they see a massive metallic structure looming in front of them? Because they can’t. Vultures, it turns out, have large blind spots above and below their heads. And because they hold their heads at a downwards angle when they fly, they are blind to everything directly in front of them.
I covered this story for Nature News. Head over there to find out why these blind spots exist, and what we can do to prevent vultures crashing into wind farms (featuring “vulture restaurants”).
Photo by M. Mirinha/STRIX
Aliens are invading Antarctica. Thanks largely to scientists, they have already established a foothold on the frozen continent, and their numbers are set to increase. This might sound like the plot of John Carpenter’s classic film The Thing, but it is very real.
The aliens in question are not body-snatching monsters, but plants from other parts of the world. Steven Chown from Stellenbosch University found that in just one summer, visitors unwittingly imported around 70,000 seeds to Antarctica. And even though the continent has a reputation for being harsh and desolate, many of these immigrants have already founded populations in their new homes.
This is a new chapter in an old story. Wherever humans go, seeds hitch a lift on our clothes and belongings. If these foreigners germinate where they don’t belong, they can often out-compete native plants and uproot local ecosystems. From Japanese knotweed to kudzu vines, these invasive species cause problems throughout the world. Inhospitable though Antarctica is, it’s not immune to such invasions. It does, however, present a valuable opportunity to study them.
In most cases, we can only see the results of plant invasions when it’s too late. We know that many species are brought into new places accidentally, but it’s hard to quantify how often this happens. You can hardly stop everyone entering a country and count the number of seeds that they’re carrying. Except when you can. Travel to Antarctica is so limited that Chown managed to stop 2 per cent of all the visitors in a single summer and count the number of seeds on their persons and belongings.