Review the item:
Josie, Don's Cairn terrier, will bark at anything that
moves,
squirrels, wind-blown leaves, passing cars, and her own shadow will
start her yapping.
For a sentence to be fused, you must have two complete sentences run together with no punctuation. In the example above, a comma joins the two sentences. Josie, Don's Cairn terrier, will bark at anything is one sentence. Squirrels, wind-blown leaves, passing cars, and her own shadow will start her yapping is the second sentence.
Thus, this error is a comma splice.
To fix the problem above, you could put a semicolon between moves and squirrels.