Red squirrels love hazel nuts. When they pick one up which still has the husk attached, they’re likely to remain where they found it while chewing off the husk, as this one is doing, before running off to bury the nut elsewhere. If they left the husk on, it would probably start to decay, and this process could transfer to the nut in the shell. Removing the husk far from where it will be buried ensures that nut thieves aren’t alerted to the cache site.