# Long-clawed shrew winter skull adaptations

> Live situation record from CLSTR: https://clstr.news/situations/long-clawed-shrew-winter-skull-adaptations
> Updated: 2026-09-08T00:36:58.000Z. Sources: 2. Developments: 2.

Research into long-clawed shrews has revealed complex skull remodeling processes used to survive winter. While many small mammals undergo Dehnel’s phenomenon—a seasonal shrinking of body mass, brain size, and skull dimensions to conserve energy—studies show these shrews actively remodel their skull shapes, with overall size decreasing by approximately 20%.

Further analysis identified a unique adaptation termed the “reverse Dehnel’s phenomenon.” While most of the skull and braincase shrink during winter, the shrews' snouts temporarily expand, increasing in height by 7% and width by 6%. Scientists theorize this expanded nasal cavity may house an increased vascular network to warm freezing air before it reaches the brain. These morphological changes are reversible, with skull structures returning to larger sizes by late summer and autumn.

## Timeline

### 2026-09-08: Shrews remodel skull shapes to survive winter cold

Researchers at Hokkaido University discovered that shrews remodel their skull shapes seasonally to cope with winter cold and food scarcity, a complex version of Dehnel’s phenomenon.

2 sources. https://clstr.news/cluster/shrews-remodel-skull-shapes-to-survive-winter-cold

### 2026-08-18: Long-clawed shrews expand snouts in winter to survive cold

A study reveals that long-clawed shrews in Japan undergo a “reverse Dehnel’s phenomenon,” where their snouts expand during winter to help survive cold temperatures while their braincases shrink.

3 sources. https://clstr.news/cluster/long-clawed-shrews-expand-snouts-in-winter-to-survive-cold

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Cite as: Long-clawed shrew winter skull adaptations. CLSTR, https://clstr.news/situations/long-clawed-shrew-winter-skull-adaptations