Did you ever watch The Waltons? This was the show about the family living in the Blue Ridge Mountains during the Great Depression. At the end of each show, the family members would say goodnight to each other from different parts of the house. “Goodnight John Boy!” “Goodnight Grandpa!” “Goodnight Mary Ellen!” If you remember this, now you have a good idea what its like in the chimp house at the end of the day (and you know how exciting my Friday nights were as a kid).
After dinner is over, the chimps all head their separate ways to build nests throughout the building. Some sleep in the catwalks, some sleep in the loft, some stay in the front rooms where they had dinner. But when the lights are turned off, they begin to vocalize to each other. This is called a “nest grunt” (or so I’ve read – I don’t remember learning the name for this in school so I googled it!). Some are more breathy, some are more like hoots, but all are fairly quiet (its bedtime, after all). What’s really neat is that we humans can start things off – if I don’t hear the chimps say goodnight, I will let out a little “hoohuhhoohuh” and all of the chimps will respond.