Q: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
The animals reduce the size of their brains and skulls as winter approaches and regrow them in the spring, say researchers 
  
 They use echolocation to explore their habitat and produce an unpleasant scent to avoid being eaten by cats. But the common shrew has another survival trick: as winter approaches, its skull shrinks and then regrows in the spring. 
  
 Dubbed “Dehnel’s phenomenon” after the scientist who first spotted the effect, the shrinkage has previously been studied by looking at the skulls of shrews that died at different times of year. 
  
  
  
 But since the changes weren’t followed in the same animals, it was not clear whether other factors might be responsible, such as smaller shrews being better able to survive the winter months. 
  
  
  
 Now researchers say they have finally shown the phenomenon is real. 
  
 “Now for sure we can say this is happening [within] individuals – we can really talk about the shrinkage and regrowth,” said Javier Lázaro, co-author of the research from the Max Planck Institute for Ornithology. 
  
 The phenomenon, he adds, appears to be an unusual way to prepare for the harsh months of winter. 
  
  
  
 “These animals cannot hibernate [and] they cannot migrate and they live in a very seasonal environment – so they need some alternative strategy to deal with winter,” said Lázaro, adding the shrews need to eat near-constantly to survive and that smaller animals need less food. “If you shrink an organ like the brain which is disproportionally more ‘expensive’ than other kinds of tissue you might save energy,” he said. 
  
  
  
 Writing in the journal Current Biology, Lázaro and colleagues from Germany and the US report how they captured shrews of the species Sorex araneus, or “common shrew”, between summer 2014 and autumn 2015. 
  
 Facebook Twitter Pinterest The pygmy shrew, Sorex minutus, which also undergoes Dehnel’s phenomenon. Photograph: Christian Ziegler 
  
 The team measured each animal’s body mass and took X-rays of its head while the creature was under anaesthetic. The animal was then microchipped and released back to the same spot. 
  
 In total 37 shrews were captured more than once by the team, allowing the researchers to explore changes in the skulls size of individual creatures as the seasons changed. 
  
 The results reveal that the animals’ body mass changed over the year: during the autumn it fell by 17.6%, before increasing by 83.4% in the spring, ahead of the onset of the breeding season. 
  
 However the animals’ skulls also changed in size, with the height of the shrews’ brain cases decreasing just over 15% on average during the autumn, before regrowing by 9.3% during the spring months. 
  
  
  
 What’s more, while shrews generally don’t live for much more than a year, data collected from a small number of elderly creatures reveals that they appear to undergo a second shrinkage in skull size as they approach a second winter. 
  
 “The fact that they shrink a second time in a second winter, really suggests [a] correlation between seasonality and the skull size and not just an ageing effect,” said Lázaro. 
  
  
  
 But, he added, mysteries remain, not least why the brain case does not completely regrow in adults in the spring (leaving them with a smaller skull than juveniles despite having a greater body mass), how exactly tissue is reabsorbed to generate the shrinkage, and what is driving the effect. 
  
  
  
 “We don’t know [to what extent] this is genetically programmed, and to which point this is influenced by environmental factors,” said Lázaro, adding that his current research is looking at how the brain itself also shrinks, and the effects of such changes on the animals’ cognition and behaviour. 
  
 But, it seems the common shrew is not alone: research has revealed that other species of red-toothed shrews as well as weasels appear to show Dehnel’s phenomenon. 
  
 Dr Allan McDevitt, a shrew biologist from the University of Salford who was not involved in the study, said that the research highlighted the drastic changes some species of shrew undergo to cope with the cold. But, he added, the research also threw up conundrums about how such animals might respond to climate change, and might also have ramifications for human health. 
  
 Dr Anna Champneys, an expert in small mammals at Nottingham Trent University, described the study as fascinating. “If scientists can work out how skeletons grow and shrink it will aid our understanding of skeletal diseases and could potentially provide a cure one day,” she said. ||||| Right now, as autumn descends upon the Northern Hemisphere, many animals are preparing for the frigid and lean winter months. Bears are going through a serious bulking phase. Hares and stoats are changing the colors of their coats. Oh, and shrews’ heads are shrinking. New research shows that the skull of at least one variety of shrew actually shrivels in size every winter. 
  
  
  
 The research team, led by scientists at Germany’s Max Planck Institute for Ornithology, not only discovered that the shrews sport this surreal, skull-wilting ability, but that they shrink their skulls repeatedly and on a seasonal cycle. The shrews’ skulls shrink during the winter, but then miraculously grow back nearly all their original mass in the spring and summer, according to new research published today in the journal Current Biology. This sets the shrews up to do it all over again at the end of the year, which honestly sounds like they’ve been saddled with some cruel, recurring witch’s curse. 
  
 There was some initial inkling that a seasonal pattern was at play. Scientists had previously described an odd relationship between skull size and season in some shrew and weasel species, where winter was full of individuals with smaller skulls, and summer was dominated by animals with comparatively voluminous noggins. This observation—termed “the Dehnel phenomenon”—was first reported by Polish zoologist August Dehnel in the early 20th century, and alternatively sounds like the title of next summer’s poorest performing young adult science fiction film. 
  
 Generally, it was thought that the Dehnel phenomenon was produced by population filtering effects of the passing seasons, where larger individuals (with larger heads) simply didn’t live through the winter as readily as their smaller compatriots. This is an understandable hypothesis to make, considering the other option was that shrews were expanding and contracting their skulls like a slowly beating heart. This is objectively crazier, and also, in one of nature’s lovely twists, apparently the accurate explanation. 
  
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 By tracking the skull measurements of wild common shrews (Sorex araneus) over the course of a year, the researchers were able to show how individual shrews shrank and regrew their skulls. They trapped shrews and took detailed x-ray measurements of their skulls. Before being released back into the wild, the shrews were also anesthetized and implanted with a microchip, allowing for identification of specific individuals for any recaptures. The research team was able to recapture a dozen shrews at three points over the year—winter, spring, and summer—and measure their skulls at each timepoint. 
  
 The shrews experienced some rather incredible changes, losing as much as 20 percent of their skulls in the winter months, and regaining 15 percent later in the year. The recaptured shrews all showed the same annual pattern: the skulls were largest in the summer, waned in the winter, and then rebounded in the spring. Much of the shrinkage occurred around the shrews’ braincase, substantially flattening its roof. It’s not yet known how the shrews are able to accomplish this. It’s possible that tissue where skull bones meet is reabsorbed, shrinking the braincase volume, and then regenerating those same sutures in the spring. 
  
 This is obviously awesome and weird as hell, but...why? 
  
 The answer may reside in other anatomical seasonal changes. Alongside the shrinking skulls, shrew brains lose a hefty portion of their mass, and there is also winter reduction in organ size and spine length. In this study, the shrews managed to lose about a fifth of their body mass overall. This rollback on specific areas of the shrew bod’ might be an energy-saving adaptation, throttling down disproportionately calorie-sucking apps like brains. Shrews don’t hibernate or migrate, so they have to overwinter as is—which is a condition not well-suited for times of wintertime food scarcity. Shrews may look like mice, but they are close relatives of moles and hedgehogs, are voracious invertebrate-devouring mini-predators, and have famously-extreme metabolic rates—sometimes requiring their own body weight or more in food daily. Mercilessly cutting back on energy output by downgrading whole organs might be the only way these little guys can make it through winter without starving. 
  
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 Whatever the reason for this seasonal shrinking, figuring out how shrews pull it off may be of importance to humans. The researchers note that if shrews can reverse their own bone loss, we could potentially co-opt the process for treatment of degenerative bone diseases in humans. 
  
 [Current Biology] 
  
 Jake Buehler is a Seattle area science writer with an adoration for the Tree of Life’s weird, wild, and unsung—follow him on Twitter or at his blog. |||||
A:
Shrews have a bonkers and heretofore undiscovered ability that Gizmodo states sounds like "some cruel, recurring witch's curse" but that scientists say is most likely a survival mechanism. According to a study published Monday in Current Biology, the wild common shrew shrinks its skull—by up to 20%—during the winter before regrowing it in the spring. And that's not all. Nature reports shrews also shrink other parts of their bodies, including their spine, heart, lungs, and spleen. Their brain mass drops by 20% to 30%, and overall body mass can shrink by more than 17% during the winter, according to the Guardian. As Gizmodo puts it, it's "obviously awesome and weird as hell." Scientists had noted the discrepancy in shrew head size between winter and summer as far back as the early 1900s, but the common explanation was that large-headed shrews were simply dying off in the winter. The real reason appears to be much stranger. Researchers caught, X-rayed, tagged, and released numerous German shrews, which live 14 months or so on average. They ended up recapturing and X-raying 12 shrews in three key seasons. They found the skulls, brains, and bodies of those shrews actually shrank and regrew depending on the season. This could be a way to conserve energy when food is scarce as "the brain is energetically so expensive," biologist Javier Lazaro says. Researchers now hope to discover if wintertime shrews are cognitively impaired compared to their summertime selves. (Meanwhile, the brains in Spain are small because of rain.)