A tattie is a potato (tattie-peelin, bafflingly, means to be affected or pretentious) and a bogle is an evil sprite.
And a tattie-bogle?
Would that be some nasty power which makes potatoes go bad? Some sort of blight sprite, in fact?
Or would that be the unfortunate habit potatoes have of shrinking the waistbands of all one's favourite clothes?
A tattie-bogle is a scare crow.
Illustration by Carus.
Potatoes were a vital and common crop in Scotland in the 1800s, but I've never heard of birds eating potatoes (wouldn't they have to dig them up, first?) so I can only guess that perhaps the tattie-bogle was put there to frighten spirits away from stealing the potatoes.
In any case, the principle remains: it's best to avoid the tattie-bogle look if you can.
Thing Not To Be Today: a tattie-bogle. Bogle comes from the Scots bogill, perhaps from Gaelic. The Middle Welsh bwg means ghost.