How small a hole can a mouse get through? Experiments.

The sound effects alone was worth the watch of this experimental video with over 18M views, involving one mouse, some peanut butter, various sizes holes... and a shrew?...

Experimenting with how small a home a mouse is able to fit through.  But it didn't go as planned.  I had a lazy mouse, and a hard-working invading shrew.

Update:  Two days later, the shrew squeezed itself through the 16.5 mm hole (See 2nd video)

Matthias Wandel

Shrew squeezes through 16.5 mm hole, epic struggle

In my previous mouse video, I said the shrew never made it through the 16.5 mm hole.  But two days after that video It actually did make it in there!