Shrews get through winter by shrinking their brains

SHREWS save energy in the winter by shrinking their brains and skulls, scientists have found.

The unusual ability in the animals – which do not hibernate – could help them to survive tougher conditions when food is scarce.

It was found the mammals can shrink their heads by up to 30 per cent as winter approaches, reabsorbing tissue into the body. The shrew then enlarges it again in spring until it is almost its previous size.

Researchers discovered the phenomenon after taking X-rays of 12 common shrews captured during dif- ferent months, before scanning them at regular intervals over a year.

In the study, published in the journal Current Biology, all 12 showed the same pattern of peak head size in summer, a reduction throughout the winter and regrowth in the spring.

Lead scientist Dr Javier Lazaro, from the Max Planck Institute for Ornithology in Germany, said: ‘Reducing head size – and thus brain size – might save energy ... as the brain is energetically so expensive.

‘Every single individual undergoes this change every winter, which remains baffling to us.’