Spot Shape Is Meaningful in Giraffe Social Circles

Masai giraffes.

Source: Courtesy of Sonja Metzger

A new study suggests that the spot patterns decorating giraffes’ coats may serve a social function. Researchers, writing in the Journal of Zoology, found that female giraffes prefer to associate with other females that have similar spot shapes. This extends previous findings that the spot patterns of female giraffes vary among individuals and appear to be heritable from mother to offspring. Together, the research suggests that individual differences in spot patterns may allow giraffes to recognize one another and potentially signal relatedness, thereby mediating social interactions.

Observing Giraffes

Giraffes have unique spot patterns that do not change from birth to death. These patterns are like human thumbprints, according to Kin Morandi of the University of Zurich, one of the authors of the new study.

Morandi is part of a team that began studying a population of Masai giraffes in northern Tanzania in 2011. She and her colleagues have been identifying and monitoring giraffes over time to investigate their biology, ecology, and behaviors. Research like this has shown that giraffes have a fission–fusion social system, with temporary groups that merge and split throughout the day, but females form long-term associations.

“Giraffe groups at any given time are quite unstable,” says Morandi. “But over a longer period of time, we start to see patterns emerging of certain females being in the same group together more often, and their relationships with each other are stable over at least six to seven years.”

Masai giraffe.

Source: Kandukuru Nagarjun, via Wikimedia Commons. Distributed under a CC BY 2.0 license.

Previous studies documented that female giraffes tend to cluster with their family members. In addition, a past study found that some spot characteristics may be passed down from mother to calf. Morandi and her colleagues put these findings together and hypothesized that females that group together should have more similar spots.

Familiar Patterns

Morandi says the fieldwork involved driving around from dawn to dusk looking for giraffes. The researchers collected data on locations and memberships of temporary giraffe groups, identifying individuals by photographs of their spot patterns. Once the photographs were collected, Morandi analyzed and categorized general traits of the spots (like roundness, size, shape, and orientation).

“I spent many hours painstakingly quantifying giraffe spots from the photographs on the computer!” says Morandi. “But it was worth it, as we were able to determine that these spots are indeed highly variable among females and spot traits are correlated with female relationships.”

Specifically, the analyses revealed that female giraffes prefer to associate with other females that have similar spot shapes. Given that a previous study found that spot shape is similar between mothers and offspring, the researchers suggest that relatedness impacts both spot pattern similarities and female social relationships.

“It is possible that the spot patterns are an easy way for females who have split off from their associates to recognize their relatives, as well as their own calves, as they regroup,” says Morandi.

Masai giraffes.

Source: Svein-Magne Tunli, via Wikimedia Commons. Distributed under a CC BY-SA 4.0 license.

Multipurpose Spots

Morandi and her colleagues think that spot patterns of giraffes could be a visual cue for communicating and for recognizing family members, in addition to other serving other functions like providing camouflage for baby giraffes.

For future studies, Morandi says there is still much to learn about the role of giraffe spots. She’d like to see more investigations of how this pattern could be perceived by giraffes and also other animals, such as predators, insects, and birds.

“This is only a small part of the biology of the giraffes,” says Morandi. “However, by putting together all the knowledge we have about them, we could understand them better and therefore we would be able to protect them better.”