Every morning we let the chimpanzees out to roam their 250-acre enclosure after a night indoors. Their breakfast is scattered around to simulate a natural environment and encourage foraging - a behavioural enrichment. The chimpanzees therefore, waste no time getting out and exploring. But yesterday something strange happened.

After getting out of the house, without any discernible signal to any of us caregivers, every one of the chimpanzees; the adults, the youngsters, everyone - even Oscar the alpha male stopped walking and sat down. They not only stopped walking, they stopped moving and communicating. Even the young ones, who are always hyper and making noises, got quiet!

The quiet was absolute and filled the whole Sanctuary. The chimpanzees didn’t focus on anything at all; they just gazed off into the distance. We all tried to focus in the general direction they were looking at but couldn’t see anything. There was no fidgeting, no touching, grooming or any discernible activity for almost five minutes! Then everything went back to normal and the chimpanzees got on with their day. I really wonder what was going on and what went through the chimpanzees minds.