Noisy Neighbors

I live on the top floor of a 3-story apartment building. We have squirrels running around in the attic above. I know this because I can hear them plain as day. It sounds like they are running directly on the sheetrock that is our ceiling. I wonder where is the insulation that should be muffling the tread of their not-so-tiny feet? I sometimes wonder if they have taken up the insulation and made a rodent palace in one corner for themselves. Yesterday Sarah thought there was something in the heating duct just behind the vent. I didn't see anything and I'm hoping it was ON the duct and not IN the duct.