COUNCIL CHRONICLE – Shrews, these tiny grey mammals seem to be better adapted for surviving the colder seasons and passing over the warm months than initially believed. Namely, the species can shrink its body size, including that of its head, in accordance with the season and its demands.
Anyone observing shrews can easily notice that they are larger in the summer than in the winter. As some believed that the smaller specimens might die during the cold months, a team of researchers decided to investigate this theory.
Adult Shrews Are Double in Size During the Summer
The research team conducted its study in Germany, where they used live traps to capture specimens of this tiny mammal. They captured Sorex araneus or common shrews, measured them, released them, and then repeated this action.
Some 100 specimens were captured in the spring, had their size measured and their brains and skeletons analyzed through X-rays and computer imaging. They were then released and recaptured several times the following year. Of the 100 captured, 37 shrews were caught more than once.
These helped reveal that the same specimen can decrease in size during the winter and increase in the summer.
“We don’t know why for sure why this happens. We hypothesize that they have developed these shrinkings to face the winter months when they have less food,” states Javier Lázaro, part of the study and the Max Planck Institute for Ornithology.
The team of researchers was also rather surprised to note that the skeleton, skull, and brain of the shrews shrunk as well. Specialists are still unsure how this might be affecting their intelligence.
In general, the team noted that, during the winter, a common shrew weighs around 6 grams while an adult summer one has about 14 to 15 grams. This is an advantageous adaptation for a species that can’t leave its environment but has few winter food sources.
It is a fascinating change, which could have broad implication as these mammals can regenerate their bone tissue in a still unknown mechanism, claim the researchers.
Current study findings are available in a paper in the journal Current Biology.
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