ARUSHA, Tanzania–Masai giraffes are the world’s tallest herbivores and beloved by people around the globe, but were recently classified as an endangered species by the International Union for Conservation of Nature (IUCN). New research published in Oecologia showed how food, predators, and people all influence giraffe social behavior. In particular, the international team of researchers from University of Zürich and Penn State University pinpointed the special requirements needed by mother giraffes to keep their babies safe, which can help land managers to protect the places most important for giraffes.
“Like all herbivores, giraffes need to find quality food to survive, but also need to avoid lions, or at least see them coming,” noted Monica Bond, PhD candidate at the Department of Evolutionary Biology and Environmental Studies, University of Zürich, and lead author of the paper. “Giraffes in our huge, unfenced study area can choose from among many different places to spend their time – places with different kinds of trees and bushes, and places deep inside protected parks or closer to farming towns or ranchlands where people live. There are lots of options in this landscape, including fewer lions outside the parks versus inside. So we wondered, how do these options influence giraffe grouping behavior? These data helps us know what places are most important for these magnificent animals.” The study found that groups composed of adult giraffes were food-focused, not affected by predation risk. Adults formed the largest groups, up to 66 individuals, in the rainy season when food is plentiful, but smaller groups during the dry season when food is harder to find. In contrast, predation risk was a very important factor influencing congregations with calves.
“Giraffe calves are vulnerable to being killed by lions and other carnivores, while adults are typically large enough to escape predation,” stated senior author Barbara König, professor at the University of Zürich. “We were testing hypotheses about mother and calf behavior to see if their strategy was for calves to hide in thick bushes to avoid predators, be in the open to see predators coming, or be in large groups for many eyes and lower individual risk.” The researchers documented that in areas with the most lions, groups with calves were found more often in dense bushes than open grasslands, and those groups were smaller in size. This suggests giraffe mothers and calves have a strategy of hiding in dense bushes, rather than staying in open areas to better see lions, or gathering in large groups to dilute the predation risk. These results mean that dense bushlands are important habitat for giraffe calves and should be protected. Some cattle ranchers promote shrub removal to encourage grass for their livestock, but they share the rangelands with giraffes and other browsers that use shrubs.
The study also explored the influence of humans on giraffe grouping behaviors. “Outside the parks the human population has been rapidly expanding in recent years,” said Derek Lee, associate research professor of biology at Penn State University and co-author of the study. “Therefore, we felt it was important to understand how human presence affected grouping behavior, as natural giraffe habitat is ever-more dominated by people.” Interestingly, adult females with calves were more likely to be found closer to traditional pastoralist compounds called bomas, made by livestock-keeping, non-farming people. “We suspect this is because the pastoralists may disrupt predator behaviors to protect their livestock—and this benefits the giraffe calves,” noted Lee. Conversely, calf groups avoided areas close to farming peoples’ towns, suggesting a difference between traditional bomas versus more densely populated human settlements for giraffe mothers seeking food and safety for themselves and their calves.
“We were happy to find that traditional human settlements by ranchers appear to be compatible with the persistence of giraffe populations,” stated Bond. “But on the other hand, disturbances around towns likely represents a threat and should be limited in areas favored by giraffes.” The study was part of the world’s largest giraffe research project and used data from six years of systematic seasonal surveys across a 2,000 square kilometer area. Learn more about giraffe research and conservation at http://www.wildnatureinstitute.org/giraffe.html
What you can do to help save giraffes:
- Donate Money or Time. Giving money and/or donating time to conservation groups like Wild Nature Institute is a great action to help giraffes. People can use their skills by providing advice, services, or goods in their personal area of expertise that can help the cause.
- Raise Awareness about the Silent Extinction of Giraffes. Speak up within your social circles, and encourage others to donate money or time to saving giraffes. You can raise awareness in your home communities by writing, speaking, and contributing to the global conversation about our planet’s climate and biodiversity crises. Use Hashtags #standtallforgiraffe and #wildnature
- Plant Native Trees. Giraffes and many other species need native trees, but deforestation continues worldwide. Planting native trees helps fight the global climate crisis and helps biodiversity too!
- Support Legal Protections for Wildlife. Laws like the Endangered Species Act and other environmental laws make the world safer for wildlife and people. Call and write to your congressperson, senator, governor, and president telling them you support strong law enforcement to protect wildlife.
- Volunteer online to help measure giraffes at our Zooniverse project (https://www.zooniverse.org/projects/derekedwardlee/measuring-giraffes ).
Bond ML, DE Lee, A Ozgul, B König. 2019. Fission–fusion dynamics of a megaherbivore are driven by ecological, anthropogenic, temporal, and social factors. Oecologia https://doi.org/10.1007/s00442-019-04485-y