What does “мышка-норушка” mean in the Russian tale Teremok?

In the folk tale Теремок (“The Little Wooden House”) each animal has a rhyming double name. Мышка-норушка is the mouse who lives in a burrow (нора), лягушка-квакушка is the croaking frog (квакать, “to croak”), and зайчик-побегайчик is the running bunny. Every Russian child knows these names; they are as fixed as “Little Red Riding Hood.”

The rest of the cast follows the pattern: лисичка-сестричка (fox-little-sister) and волчок-серый бочок (little wolf, grey flank), until the bear arrives and squashes the house. The tale opens with the famous line стоит в поле теремок, and the clip’s narrator adds из трубы идёт дымок, “smoke rises from the chimney.”