Shrews Grow Bigger Snouts in Winter, Shrink Brains, Study Finds

A new study reveals that long-clawed shrews in Hokkaido, Japan, display a unique adaptation known as 'reverse Dehnel's phenomenon.' During the winter, their snouts grow longer while their brains shrink, which goes against what we thought about how small mammals adapt to seasonal changes. Published on August 19 in Proceedings of the Royal Society B, the research examined 136 skulls collected between 1948 and 1988 from Hokkaido University’s Botanic Garden. Led by Yugo Ikeda from Toyo University, the findings show that winter shrews have snouts that are 7% taller and 6% wider than those in spring. This might help them regulate body temperature or improve their sense of smell for hunting under the snow.