Who’s the mummy? Markéta Gloneková

Baby giraffes have got some cheek. They seem to use stealth to steal milk from giraffes that are not their mothers, at least in zoos.

About 40 per cent of their suckling is from non-mothers, which is the highest rate recorded in any non-domesticated mammal. This is unexpected since milk is costly to produce, so a mother is expected to save it for her own offspring. So what is going on?

It might be down to simple theft, according to Marketa Glonekova and Karolina Brandlova at the Czech University of Life Sciences in Prague. But it might also be to do with reciprocity in social groups of female giraffes and their young.


The team observed 24 nursing mother giraffes and 37 suckling calves at four zoos in the Czech Republic between 2007 and 2011. They saw 83 per cent of mothers nursing a calf other than their own, and 87 per cent of calves suckling from a female that wasn’t their mother.

The thieving calves usually went in for milk at the same time as the biological offspring, appearing to hide behind them in what looked like efforts to conceal their identity. Mothers seemed more willing to tolerate calves whose mothers also nursed other calves. But there was no direct reciprocity between pairs of mothers when it came to nursing each other’s young.

Marina Horvat/imageBROKER/Rex Shutterstock

The arrangement is surprising, says Brandlova, but it fits with our growing understanding of giraffe social behaviour. Miho Saito and Gen’ichi Idani of Kyoto University, Japan, who studied giraffes in Tanzania, recently reported that social bonds between females strengthen after they give birth, perhaps to allow them to share nursing behaviour and be more vigilant against predators such as lions.

“Recent studies of giraffe sociality show us the existence of an elaborate social system,” says Brandlova. “Giraffe calves stay together in small groups protected by one adult female while their mothers are searching for food.”

In a zoo, giraffes have plenty to eat, so the cost of producing extra milk might not be so burdensome. It’s not yet clear how common this behaviour is in the wild. Saito says she has never observed two wild calves suckling from the same mother. But she only observed giraffes during the dry season, when food is scarce and of low quality. It would be interesting to see if such nursing of others’ offspring happened during the rainy season when food is more abundant, she says.

Journal reference: Animal Behaviour, DOI: 10.1016/j.anbehav.2015.11.026; African Journal of Ecology, DOI: 10.1111/aje.12268

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