Mountain goats are not avalanche-proof
News and notes about science
Mountain goats are high-elevation daredevils, learning to balance upon the steepest of rocky edifices soon after they are born. Nannies lead their kids up gnarly slopes, seeking places that predators fear to tread. While the precarious perches help goats avoid being eaten, there is an obvious downside to these sanctuaries: avalanches.
While scientists have long suspected that this life on the edge was risky, they have not really understood the extent to which avalanches affect mountain goats, and whether they instinctively shun, or can learn to avoid, avalanche-prone conditions. While the behavioral question remains a mystery, a study published Monday in the journal Communications Biology, based on nearly two decades of research in Alaska, shows that cascades of snow are a major killer, substantially affecting the animals’ populations.
Kevin White, an ecologist at the University of Victoria and the University of Alaska Southeast and lead author of the study said, “We’ve often thought of snow as a major driver of populations,” of mountain goats. But the difficulty of studying their rugged, inaccessible habitats has limited understanding of what avalanches do to the animals’ numbers. That is compounded by a bias toward summertime research on the animals.
Typically, “people don’t go out in the winter, and they don’t go out in these conditions,” said Eran Hood, a snow hydrologist at the University of Alaska Southeast and an author of the study.
Over 17 years of field work with the Alaska Department of Fish and Game, White fitted radio collars on 421 goats in the Klukwan, Lynn Canal, Baranof Island and Cleveland Peninsula regions of southeastern Alaska. He surveyed the animals’ locations, following their movements from aircraft as the pulsing collars indicated whether the goats were alive or dead. When mortality was detected, White swooped in by helicopter. Then, if it was safe to land, he gathered post-mortem clues. Then he worked with a group of colleagues to make sense of the mortality data.
Data from the collared goats revealed that snow slides barreled down not just on inexperienced kids but on breeding adults as well, especially females in their prime. Avalanches were deadly, explained White, and caused 65% of all deaths in one of the regions studied.
In southeastern Alaska overall, “it could mean that 8% of the population, on average, is dying from avalanches; and in some of the worst years, it was over 22%,” White said. He concludes that “avalanches may be a much more important driver of populations than previously expected.”
Fanie Pelletier, an ecologist at Université de Sherbrooke in Quebec who studies bighorn sheep, and was not involved in the goat study, was surprised by the high avalanche mortality rate. With so many individuals monitored over 17 years and data drawn from four sites, she called the study “robust.”
Elizabeth Flesch, a wildlife geneticist at Montana State University agrees. “It’s pretty impressive they were finding collars under avalanche debris,” she said, noting that in survival studies, assigning the cause of death is often difficult.
That these avalanches were burying prime-age females “is a really big deal,” said Flesch, who was also not involved in the study, because when females are disproportionately removed from a population, recovery is slow.
Wesley Sarmento, a mountain goat expert at Montana Fish, Wildlife & Parks, called the study innovative. “Mountain goats are particularly susceptible to climate change, so more of this kind of research is important,” he said. But he cautioned that it remains to be seen whether the patterns in southeastern Alaska hold true elsewhere.
Pia Anderwald, a researcher with the Swiss National Park in Zernez, Switzerland, who studies antelope-like chamois and other hoofed Alpine mammals, was not surprised by the number of goat avalanche deaths in the study. She added that because only adults were collared, “kids and yearlings may have been underrepresented.”
She also doubts the researchers’ conclusion that goats can’t learn about avalanche risk. As a species that evolved in this terrain, “I’d be surprised if they didn’t have any means of assessing dangerous areas,” she said. “They watch each other.”
And as climate change affects snowfall patterns and the future likelihood of avalanches, the goats will need to keep an eye on that too.
Indeed, avalanches are not new. So White’s next challenge is to determine why goats court such danger. He suspects that if the costs of clambering in risky places are high, the benefits — such as fewer predators, and fabulous food — must be high, too. No kidding.
— Lesley Evans Ogden
Swimming beneath sand, it’s ‘the hardest of all animals to find’
If you saw a northern marsupial mole, you might be surprised. Known to the First Nations peoples in the Western Desert of Australia as the kakarratul, it is eyeless and has shaggy golden fur. Just 4 inches from nose to tail, the animal would fit in the palm of your hand. And unlike the mole species of North America, it is a marsupial.
But you probably wouldn’t see one. While the animals are plentiful, sightings remain extremely rare because northern marsupial moles live in tunnels beneath sand dunes, navigating them with a swimminglike motion using flipperlike front feet.
“This is the hardest of all the animals to find,” said Denzel Hunter, an Indigenous ranger who works to survey and conserve wildlife in the lands of the Nyangumarta people. “Every time we go out looking for northern marsupial moles, we find evidence that they’re there. But I’ve never seen one.”
Kanyirninpa Jukurrpa Martu rangers recently found a kakarratul in the Great Sandy Desert, nearly 1,000 miles northeast of Perth. Their photographs of the creature expand scientific knowledge of the species as well as of the wider desert regions that make up close to one-third of Australia’s land mass.
The find also highlights the value of the 60 desert ranger groups that oversee much of Australia’s national system of protected areas.
“It’s once you start digging into the detail of that country with the people who know it best that you really start to get an appreciation of the place,” said Gareth Catt, who as program manager of the Indigenous Desert Alliance has worked extensively with ranger programs. “It’s the Indigenous rangers that have that enduring connection and are best placed to understand and look after that country.”
— Anthony Ham
Searching for the first glow of bioluminescence in coral fossils
Bioluminescence is used throughout the animal kingdom, particularly in marine environments, to lure prey, startle predators and even act as camouflage in the surrounding light.
“We always say it’s light-limited in the deep sea, but there are a lot of organisms that produce their own light,” said Andrea Quattrini, a zoologist at the Smithsonian National Museum of Natural History in Washington.
The dazzling glow of bioluminescence is common in Octocorallia, also known as octocorals, a class of more than 3,000 Anthozoa species including sea fans, sea pens and soft corals. The prevalence of bioluminescence in these sessile animals makes a lot of sense, Quattrini said: “They settle somewhere and they’re there.”
How long organisms have been able to emit light is at the center of recent research by Quattrini and colleagues. Their latest study, published in the journal Proceedings of the Royal Society B, resets the timing for the emergence of bioluminescence back to about 540 million years ago, from the existing understanding that it appeared in small marine crustaceans 267 million years ago.
The researchers based their finding on recent octocoral evolutionary tree work, octocoral fossils and modeling to trace the ancestral past of the tiny organisms.
Bioluminescence is believed to have evolved nearly 100 times across history, caused by a simple chemical reaction, when a light-producing molecule called a luciferin reacts with an enzyme called luciferase.
“This ability to bioluminesce is giving these animals some type of survival or fitness advantage,” said Danielle Deleo, the lead author on the study and a biologist affiliated with Florida International University and the Smithsonian National Museum of Natural History.
In the new study, the researchers incorporated dated octocoral fossils to determine when branches on the tree diverged.
— Sam Jones