The Variable Ant-Shrike is 1 of 4 Bird Species That are No Longer Found on the Cerro-de-Pantiacolla Ridge in the Peruvian Andes. - Alexander Lees
Escalator to Extinction: How Mountain Species Are Imperiled by Global Warming & Climate Change - by Richard Conniff | Yale Environment 360 - Climate - Bio-Diversity - Extinction - Global Warming - Climate Change - Conservation - Forests - Mountains | 13th/11/2018
As Per the Findings of a Recent Study, Andean Birds Were Heading Up-Hill to Keep Pace With Rising Temperatures & Would Soon Run Out of Room. It is the Latest Example of How Species are on the Move as They Struggle to Adapt to Climate Change.
A shift in home range by a handful of bird species along an obscure ridge in the Peruvian Andes might once have seemed like sleepy stuff, even to ecologists. Instead, it made head-lines last month when researchers reported that the birdsâ up-hill push for cooler terrain has already resulted in population losses for most species & the probable extirpation of 5 species that were common at the ridge top just 33 years ago.
It was some of the strongest proof yet for the long-standing prediction by experts that climate change will lead - is leading now - to widespread loss of fauna. University of British Columbia ecologist Ben Freeman & co-authors summed up their findings with a chilling metaphor: Mountain birds, they wrote, are âriding an escalator to extinction.â
The study, in the Proceedings of the National Academy of Sciences, did not report any actual extinctions. The Cerro-de-Pantiacolla rises to a maximum height of only 4,642 feet, the birds that disappeared from the ridge-top persist on higher & larger mountains - in effect, on other escalators - elsewhere in the area. Reliable scientific evidence that climate change has led to real extinctions is in fact scarce so far, despite projections by climate models on the likelihood of such extinctions. The only known example is the Bramble Cay Melomys, a marsupial which vanished sometime after 2009 from a low-lying North Australian Isle, after sea level rise & extreme weather caused repeated inundation of its habitat.
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A Shift in the Range of a Species Can Mean the Introduction of New Rivalries & the Un-Raveling of Entire Eco-Systems.
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But the new study from Peru lends support to the predictions being made by climate modelers. It also fits into a rapidly expanding body of evidence that Bio-Diversity (Flora & Fauna) everywhere is on the move as it struggles to adjust to climate change. The ecological up-heaval is âhappening right now & it will almost certainly continue to happen,â says Freeman, lead author of the Peru study, & âthere is an urgency to something happening right before our eyes, different from a study saying, âthis is what itâs going to be like in 2100.ââ
When Flora & Fauna move up-hill, they can lose habitat, simply due to mountains getting smaller the higher you climb. A shift in range can also mean the loss of old partnerships, the introduction of new rivalries, & the un-raveling of entire eco-systems. Some of the emerging struggles are small-scale & tentative, a bit like a budding workplace rivalry: On Whiteface Mountain in Upper New York, for instance, Bicknellâs thrush is state-listed as a species of âspecial concern.â (A petition to list it under the federal Endangered Species Act recently failed.) Itâs a medium-sized brown bird with a speckled throat, 40 years ago it had the mountain-top to itself. But climate change means that it must now share space with the American Robin & Swainsonâs Thrush, which have both moved in from down-hill. Swainsonâs thrush responds aggressively to the calls of Bicknellâs thrush. Whether it will eventually push it out of its old habitat may depend on a host of variables from nesting behavior to food preferences.
Other climate-induced range shifts are more like a hostile corporate takeover & can happen with astonishing speed & scale. In western Australia, for instance, ocean temperatures have risen steadily since the 1970s. But as recently as 2010, luxuriant kelp forests still dominated the shallows along 500 miles of coast north of Perth. Then 3 exceptionally warm summers in a row wiped out 43 % of the kelp. By the time the heat waves finally ended, tropical & sub-tropical fish moved into what was formerly temperate habitat. They nibbled the kelp down to nothing as it attempted to re-sprout, leading to an ecological âregime shift.â The likelihood now is that ârapid local kelp extinctionâ will progress poleward down 1,000âs of miles of coastline, according to a 2016 study in Science. And since kelp is a major nursery for marine productivity, it âwould devastate lucrative fishing & tourism industries annually worth more than Au$10 billion,â along with âcatastrophic consequencesâ for 1,000âs of endemic species.
The range shifts now in progress donât necessarily stick to the predictable pattern of species heading up-hill, or toward the poles, in search of cooler weather. When a team of researchers looked at 3 sites on protected federal lands in Californiaâs Sierra Nevada, for instance, they found that about Âœ the bird species had moved up-slope over the past 80 years, apparently in response to warming temperatures. But some species had moved downslope, due to increased precipitation - and still others didnât move at all, or moved upslope in one location & down in another as local climate conditions dictated.
An emerging pattern is that climate change appears to displace tropical species more than their temperate counterparts, though the temperate zone has experienced greater warming. That may be because temperate zone Flora & Fauna already live with âthese dramatic fluctuations,â says Freeman. âThey have to be able to deal with winter & summer. So it makes sense that a slight change in temperature might not be as consequential.â
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Predictions About How or Whether Species Will Move Can Shape the Debate About When to Intervene to Save Them.
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Species living in the rain-forest canopy may also be pre-adapted to temperature change, according to a 2017 study in the journal Global Ecology & Bio-Geography, because their treetop habitat already heats up & cools down so much over the course of the daily cycle. In a study in Panama, ants living in the canopy tolerated temperatures 3 - 5 degrees Celsius (6 - 9 Degrees Fahrenheit) warmer than terrestrial species could handle. It suggests lowland species might be more inclined âto shift to mid-elevation, & mid-elevation species to high elevation,â as a 1st line of defense against climate change, says lead author Brett Scheffers, âand high-elevation species go extinct.â It also suggests the potential for what he calls âflattening forests,â with tree-top species descending in search of cooler temperatures, leading to sudden overcrowding in some habitats.
âWe are just now starting to see research coming out describing the effect of climate changes on species interactions,â says Scheffers, a Florida University ecologist. âComprehending species interactions is really complicated. Trying to understand species in a rain-forest, where you have millions of variables ⊠it makes your head hurt just thinking about it.â Yet being able to make reliable predictions on how or if species will move can be vital for conservation planning - for instance, in deciding which habitats & corridors to protect for the climate 50 or 100 years in the future.
Scientists in Australia Have Re-Located the Western Swamp Tortoise to a New Habitat South of its Original Range in One of the 1st Cases of âAssisted Colonization.â - Perth Zoo
Those predictions can also shape the debate about when to intervene to save a species. In a controversial step known as âassisted colonization,â conservationists in western Australia have already relocated a species, the critically endangered western swamp tortoise, to a new habitat several hours south of its original home range, where it was threatened by urban development & sharply reduced water supply. But that kind of effort requires deep understanding of how the species lived in its old home & how it is likely to interact with other species in its new one. Conservationists, burned by past species introductions, are deeply conservative about assisted colonization. And yet a long list of other species, like a New Zealand bird called the Hihi, face the loss of traditional habitats due to climate change.
âWe are just starting to see extirpations,â says Scheffers. âThe worry is not just that it may happen, but that it may pick up speed. You have all these species interacting, & now climate change is beginning to remove them. Itâs like a big Jenga game,â a tower made of wood blocks where the trick is to pull out the lower pieces 1 by 1 without bringing down the whole thing. âYou wonder not only when itâs going to collapse, but what the hell is going to replace it. That should be alarming, not not just to those who care about bio-diversity,â he adds. âThe exact same changes are also occurring in agriculture & forestry.â Scientists trying to make sense of these changes now increasingly talk about âno-analog communitiesâ - ecological communities unlike any seen before. But the more frightening reality, adds Freeman, is that we may be facing a âno-analog future.â
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Richard Conniff is a National Magazine Award-Winning Writer Whose Articles Have Appeared in The New York Times, Smithsonian, The Atlantic, National Geographic, & Other Publications. His Latest Book is House of Lost Worlds: Dinosaurs, Dynasties, and the Story of Life on Earth. He is a Frequent Contributor to Yale Environment 360.
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