We recently took a mini-field trip to an alpaca farm. Prior to going, we spent some time researching and learning about the animals. One of the things we learned is that they make a humming sound. I couldn't quite catch it on video (Micah would not stop talking), but they really do hum. As we were listening to the teaching portion of the field trip, they stood behind us and hummed.
Strange. And a little annoying.
I have a twelve-year-old that constantly hums. Drives me nuts. I wonder if she even noticed that the alpacas were humming?