Is sneaking around an example of furtive behavior?

Yes, but it's not a very specific example.
Furtive behavior, by definition, is stealthy or secretive; it's done in the hope that no one will notice. Sneaking around is being furtive, but it's not a specific example of furtive behavior.
Here are a few specific examples: you might take a furtive glance at your friend's quiz paper, furtively text someone during class, or take a furtive spoonful of your sibling's dessert.
In any of those cases, you're acting slyly and sneakily because you don't want anyone else to notice what you're doing. You're being furtive.
Often, but not always, furtive behavior involves stealing something. This is why we derived "furtive" from fur, the Latin word for "thief."
Here's one more example. In Alice Walker's story "Everyday Use," the narrator describes some of Dee's friends as "furtive boys in pink shirts hanging about on washday after school." She means that the boys are acting slyly and sneakily and are hoping to avoid notice. Are these boys sneaking around? Probably. Is sneaking around an example of furtive behavior? Yes, but it's a very vague, general example. Again, a specific example would be something like "sneaking into the class before the teacher notices I'm late," "sneaking around with his date so his girlfriend won't know he's cheating on her," or "sneaking into the kitchen to take the last piece of cake from the fridge."
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