Giraffes live on a continent where danger is ever-present. Two new studies by researchers from the Acoustics Research Institute of the OeAW have now discovered how these animals detect threats. In South Africa, the researchers investigated how giraffes respond to predator sounds and to the alarm calls of other species — and showed that their vigilance is based not only on innate instinct but also on learned experience. A particularly unusual partner plays a key role in this: the red-billed oxpecker, a bird species common across South Africa.

Songbird with Warning Calls

Giraffes and red-billed oxpeckers have a mutually beneficial relationship: the songbird feeds on bothersome parasites living on the giraffe — and in return, warns its host with harsh alarm calls when predators approach. Whether giraffes actually respond to these acoustic warnings, however, depends on a crucial factor: they must first learn to interpret the birds’ alarm signals correctly.

How they learn this was demonstrated by bioacoustician Anton Baotic of the OeAW and Georgine Szipl, as reported in the journal BMC Biology.

In South Africa, the researchers used recordings of the songbird’s calls to test the reactions of giraffes — both from areas with lions and from areas without. The result:

“Our study showed that giraffes in regions with predators reacted more strongly to the alarm calls. They remained in an alert posture for longer,” says Baotic.

In contrast, giraffes living in lion-free reserves showed much weaker reactions to the same bird calls.

Well Roared, Lion

This finding is confirmed by a second study published in Frontiers in Ecology and Evolution. In that study, Baotic and Szipl examined how giraffes respond directly to predator sounds. All giraffes reacted immediately to the roar of lions — even those living in lion-free areas. However, giraffes that regularly encountered lions remained alert significantly longer.

“This underlines that giraffes possess not only an innate sensitivity to dangerous-sounding noises but that experience further strengthens their behavior,” Baotic explains.

Experience Sharpens Perception

Apparently, the proximity to predators sharpens giraffes’ senses. This allows them to perceive and interpret the bird’s alarm calls more effectively. The researchers point out that this learned behavior developed within just five years — the time since lions had been reintroduced into the reserve where the recordings were made.

Loss of Behavioral Competence

The discovery that giraffes can interpret the alarm calls of their bird partners also carries important ecological implications: when predators disappear from an ecosystem, giraffes lose the ability to recognize danger and to respond appropriately.

“We call this ecological amnesia — the loss of behavioral competence,” says Baotic.

This finding is especially relevant when giraffes are relocated to other reserves. Giraffes that have never encountered lions are less vigilant because they have not learned to associate the red-billed oxpeckers’ alarm calls with danger.