Lions eat baby giraffes. In fact, it's generally thought that the lion is the only species (aside from humans, of course) that poses a major threat to these long-necked giants, and that the big cats have a habit of going after young individuals. However, according to Zoe Muller of the University of Bristol, "no one has ever investigated if this preference for hunting calves has an impact on the [giraffe] population as a whole."
This is an important question for conservationists who are trying to preserve the dwindling populations of the world's tallest mammal, and it's why Muller spent the better part of two years giraffe-watching in Kenya. What she found was that giraffe herds look very different when there are lions about.
Giraffes may be iconic African animals, but they tend to get the short shrift when it comes to research, especially compared to fellow icons like elephants or rhinos (a recent study suggested we might even need to rethink how many species of giraffe there are). What we do know is that these animals are in trouble. According to the IUCN, giraffe numbers have declined at least 36% over the past three decades, and the remaining populations have been scattered and fragmented by habitat loss, environmental change and poaching.
Muller visited two of these populations in protected areas of the Great Rift Valley in Kenya, at the Soysambu Conservancy and Lake Nakuru National Park. She spent nine months at each location from 2010 to 2012, driving a 4x4 across the terrain and identifying Rothschild's giraffes (from a distance of hundreds of metres) by the patterns on their coats. For Muller, there was one major and important difference between the two sites: Lake Nakuru has lions; Soysambu does not.
Muller documented the sex and age of each giraffe – she counted 77 giraffes at Soysambu and 89 at Lake Nakuru – and noticed another striking difference: at Soysambu, very young giraffes (under a year old) made up about 34% of the population, whereas giraffes of that age at Lake Nakuru came in at a mere 6%.
Muller suspects this difference is directly related to the presence of lions at Lake Nakuru. "Lion predation is the main cause of death for giraffe calves," she writes in her study, "they are a preferred target and rarely survive an attack."
The big cats' habit of hunting calves leads to adult-dominated populations, which can change how these populations will grow as the generations pass. This is only the first study to examine the phenomenon, and more research will be needed to support Muller's conclusions, but the implications are significant.
"Giraffes are a threatened species, suffering ongoing decline in the wild," Muller said, "and this research highlights how managing giraffes alongside lions inside a conservation area (a common practice in Africa) has detrimental effects for giraffe populations."
The study also provides new info on long-term patterns in the giraffe population at Lake Nakuru. In the mid-1990s, there were over 150 giraffes in the park, but their numbers had crashed to below 65 by 2002. Muller’s count of 89 reveals a rebound in the years since – this might also be related in part to the lions, since the cats' population in the park has declined since 2002. This study is the first to report a population count for Soysambu.
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