Standing on its hind legs, keeping balance with the help of its tail, and holding its front legs together against its chest and stomach, the little mammal scans the open grassland and the blue sky. Suddenly its eyes are fixed on something high above. It takes me some time to spot the small black silhouette high up in the sky, which turns out to be a vulture gliding across the firmament. Yet no alarm call sends the other members of the group scrambling for safety. The little guard seems to know that this silhouette does not mean danger.