A Giraffe of a Different Color

We all know that our hair turns gray as we get older, but did you know that hair color can also change with age in various other species throughout the animal kingdom? The silverback mountain gorilla is one of the most well-known examples, where the hair on a male’s back will change from black to silvery-gray when he matures at around 12 to 14 years of age. These types of coat color changes are one way that researchers can estimate the ages of individuals in a wild population without having to examine them up close, and are considered a type of biomarker.

Thornicroft’s Giraffe
[photo courtesy of Fred Bercovitch]

Fred Bercovitch, a wildlife biologist and professor at the Primate Research Institute and Wildlife Research Center at Kyoto University, along with his colleague Phil Berry, study this phenomenon in a lesser-known color-changing species—giraffes. More accurately, Thronicroft’s giraffes (Giraffa camelopardalis thornicrofti), which are a less-common subspecies that live in the Luangwa Valley in Zambia.

Like all giraffes, these have brown geometric blotches all over their bodies, and each individual has a different pattern of these blotches. However, the markings on male Thornicroft’s giraffes darken and become coal black as the animals age—and according to a new study published in this month’s Journal of Zoology, this darkening, especially in the case of males, occurs within a limited time span as the animals age. This knowledge, in addition to the extensive observations made during the study, can help researchers better construct the animals’ life histories without knowing their exact ages.

“Not all subspecies blacken,” says Bercovitch. “So the ones you’ve seen in zoos might not change color with age.” He explained that as far as he is aware, no zoo in the world has Thornicroft’s giraffes; the most common types in captivity seem to be Reticulated and Masai.

“It’s actually pretty amazing,” he mused, “that people like seeing giraffes in zoos, they like seeing them in the wild, they are famous in the media such as in the movie Madagascar and on the Toys ‘R Us logo, but yet, very little research has been conducted on them in the wild.”

Now, this study is the first of its kind that followed known wild individuals over the course of their lifetimes, in addition to documenting color changes that ended up being especially prominent in males.

The markings on this male Thornicroft’s giraffe are turning black.
[Photo courtesy of Fred Bercovitch]

Bercovitch explained that co-author Berry has been a game ranger, safari guide, and a leader in rhino anti-poaching efforts for over 40 years, among many other jobs. He is also particularly skilled at recording giraffe data, and a lot of the information that he collected, which included relative blotch color of the males, as well as herd size, composition, and a slew of other details over the course of 33 years, were particularly useful in this study. Plus, since most of the collected information is in the form of field notes, the data is unbiased towards this particular study.

There are only a few other ways to tell the age of a giraffe if it is unknown. The first is by looking at the teeth, which erupt as the animal grows and wear down with age, much like horses. Unfortunately in the field, it is extremely hard to see the teeth, so it is really only helpful if you find a dead individual. Another method is looking at the relative sizes of the giraffes. For example, if a male is taller than a female, he is most likely at least 6 years old. If a female is seen nursing a calf, she is also most likely at least 6 to 7 years old. Finally, photographs can be compared. Since each giraffe’s coat pattern is different, if you find an old photo of an animal that matches up with a recent one, you can calculate an estimated minimum age based on when the photos were taken. Bercovitch and Berry also used a large amount of photographic records to identify and determine the ages of individuals.

Based on their long-term extensive observations, the giraffes’ color changes, and analysis of photographic records, Bercovitch and Berry were able to conjecture that male Thornicroft’s giraffes actually don’t live as long as previously thought. They found that they are weaned from their mothers and become independent by 2 years of age, then head out on their own when they are between 4 – 8 years old. Their color begins to darken later in life, when they are about 7 – 8 years old. It then takes another 1 – 2 years for them to completely blacken and become mature around 10 years of age. Most literature has suggested that male longevity is at least 25 years, but it is now known that male Thornicroft’s giraffes rarely live longer than 21 or 22 years, and their average life span is around 16 years of age. Bercovitch and Berry also determined that females on the other hand, can live up to 28 years, and have a longer reproductive life. Their color change however, is not as pronounced.

“We hope that this [new information] will not only help researchers [better determine giraffe ages] in the wild, but also can provide a basis for comparisons across locations in Africa to see if coat color changes differ depending on where these giraffe subspecies live,” says Bercovitch. In addition, they hope that by using observations of color changes, researchers may be able to gather better and more accurate data on herd composition and general ages of populations which will be important when it comes to conservation management efforts.

Giraffes are generally not considered endangered, but there are actually two other subspecies that are listed as endangered on the IUCN Redlist. These are the Nigerian AKA: West-African giraffe (Giraffa camelopardalis peralta) and the Rothschild AKA: Ugandan giraffe (Giraffa camelopardalis rothschildi). Not only are humans encroaching on their habitats causing there to be fewer and fewer large areas for them to wander across, but they are also poached in many areas.

Bercovitch hopes that this work will stimulate more interest in giraffe research, since not a lot has been undertaken in the past. He explained how important it is to *achem*… stick our necks out for these amazing and truly unique creatures. “Plus,” he said, “if the report stimulates people to go to Africa to see giraffes, that may help inspire them to save them!!”

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One Comment on “A Giraffe of a Different Color”

  1. It appears u actually understand plenty related to this specific issue and that demonstrates as a result of this particular posting, titled “A Giraffe of a Different Color The Sieve”.

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