Meerkat sentries gain trust through experience, not rank Jacob Brown

Experience beats age or rank when it comes to meerkat sentry duty. Individuals who stand guard while other group members forage for food gain trust through reputation, not through their social rank. Other foraging species that rely on sentries usually only pay attention to warnings from dominant or older individuals.

When meerkats forage for insects and other prey they bury their heads in the sand, so having a reliable lookout means they don’t have to be on the alert themselves for predatory snakes, hawks, eagles and jackals. Good lookouts save lives by giving an alarm call when a nearby predator looks ready to attack. Likewise, reliable “all-clear” calls allow peers to confidently resume foraging.

To find out what makes meerkats trust a sentinel, Ramona Rauber at the University of Zurich studied nine groups of foraging meerkats in South Africa’s Kalahari desert in 2016 and 2017. The groups ranged in size from three to 23 animals.


Super-guards

Meerkats of any age and dominance serve as lookouts. But after observing each group for three months, Rauber ranked lookouts as “rare”, “common” or “super”. Super-guards were those that stood watch at least 50 per cent more frequently than any other individual.

Rauber recorded “all-clear” calls from as many sentinels as possible, then played these back for periods of five minutes to individual meerkats temporarily foraging alone, and so free from peer influence. “I attached a small speaker to my leg while I positioned myself 1 to 2 metres from each test individual,” she says.

During each of 544 playbacks, she monitored how much time each individual animal looked up to check for predators while the tape was running.

Rauber found that the foragers looked up least while listening to recordings of “super-guards”, suggesting they put most trust in these individuals. On average, across all groups, foraging meerkats spent just 2.1 per cent of the time being vigilant if they heard a “super-guard”, compared with 3.2 per cent and 5.1 per cent when they heeded calls from “common” and “rare” guards respectively.

Other group-living animals that forage for food also rely on lookouts to warn of nearby danger. But in these species – including dwarf mongooses and pied babbler birds – it’s older or high-ranking individuals who are trusted to be reliable sentries. In contrast, “super-guard” meerkats were not necessarily old or of high rank.

Meerkats are renowned for their social intelligence: this may be what allows them to learn that any individual has the potential to be an effective lookout rather than just blindly put their trust in a dominant group member.

Journal reference: Nature Scientific Reports, DOI: 10.1038/s41598-018-29678-y