What is the effect of the word "squirrel" in the passage below?
Small flames stirred at the trunk of a tree and crawled away through leaves and brushwood, dividing and increasing. One patch touched a tree trunk and scrambled up like a bright squirrel. The smoke increased, sifted, rolled outwards. The squirrel leapt on the wings of the wind and clung to another standing tree, eating downward. Beneath the dark canopy of leaves and smoke the fire laid hold of the forest and began to gnaw.