A closer look
Soricidae, specifically the red-toothed shrew, undergo a bizarre seasonal process called Dehnel's phenomenon where they literally shrink their own skulls and brain mass by up to twenty percent to conserve energy during harsh winters. When spring finally arrives and food becomes abundant again, their skulls mysteriously regrow and their brain mass expands back to its original size. They lack the body fat to hibernate normally, so they just aggressively delete parts of their own central nervous system to survive the frost. Imagine being so cold and hungry that your body just decides to temporarily shrink your skull and make you significantly dumber until the weather improves. It puts winter seasonal depression into a new perspective!
