The steep ravine of Olduvai Gorge in Tanzania lies behind me. Ahead are the plains of the Serengeti, grasses reaching toward the far horizon in a wavering line that finally bends into the curvature of the Earth. It is June, and the Serengeti’s “long rains” have just ended. The air is washed clean by the storms of March, April and May. In this briefest of interludes before the dry season, the land is verdant. Grasses still sprout, not yet turned sere and golden.
I think of age-old migrations and thundering hooves across miles of savanna. What I don’t think of is right before my as-yet-unseeing eyes: giraffes, peacefully browsing flat-topped trees, their legs and necks nearly hidden in a copse of acacias.
With all our concern for iconic African wildlife species – lions, cheetahs, rhinos – somehow we’ve forgotten the quietly ambling giraffes.
“While giraffes are commonly seen on safaris and in zoos, many people – including conservationists – are unaware that these majestic animals are undergoing a silent extinction,” says biologist Julian Fennessy, director of the Giraffe Conservation Foundation, based in Namibia. “With a decline of almost 40 percent in the last three decades, the world’s tallest animal is under severe pressure in many of its core ranges across East, Central and West Africa.”
Human population growth poses the greatest risk to giraffes, says Fennessy. “Habitat loss and expanding agriculture and mining, illegal hunting, and increasing human-wildlife conflict are pushing giraffes toward extinction.”
Biologists report a steep decline in the overall giraffe population, from some 163,452 giraffes in 1985 to 97,562 in 2015. As a result, giraffes have moved from species of “Least Concern” to “Vulnerable” on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.
But is that one giraffe species…or several?
Fennessy and other scientists argue in a paper recently published on bioRxiv that “mounting evidence of four giraffe species proposes a re-evaluation of the current IUCN giraffe taxonomy to raise the classification to a [yet] higher level of threat, and in turn increase conservation actions.”
The four giraffes
Scientists had long recognized one giraffe species and nine subspecies. Then ecologists began an analysis of giraffe relationships. Giraffes, it turns out, are not one species, but indeed four. “The genetic differences among giraffes are at least as great as those between polar bears and brown bears,” says Fennessy.
He and geneticist Axel Janke of Goethe University in Germany led the research team. The unexpected findings highlight the need for in-depth studies of and greater conservation efforts for the four genetically isolated species, the biologists say.
“We were surprised at the results because coat patterns and other visible differences among giraffes are somewhat limited,” says Janke. “Giraffes are also assumed to have similar ecological requirements across their range, but no one really knows because they’ve been largely overlooked by science.”
The researchers looked at DNA evidence from skin biopsies of 190 giraffes. “The extensive sampling included populations of all nine previously recognized giraffe subspecies,” says Fennessy.
The analysis shows that the four overall groups of giraffes don’t mate with each other in the wild. As a result, the scientists believe, giraffes should be recognized as four distinct species: northern giraffe (Giraffa camelopardalis); southern giraffe (Giraffa giraffa); reticulated giraffe (Giraffa reticulata); and Masai giraffe (Giraffa tippelskirchi).
Why did giraffes separate into different species? Rivers, mountains and other geographic barriers may have kept populations apart long enough for new species to evolve, Fennessy says.
All giraffes are quintessential African savanna animals. That savanna, however, is vanishing. It once covered an area one and one-half times as large as the lower 48 U.S. states. Along with the grasslands, giraffes are disappearing.
Northern giraffes, for example, number fewer than 5,000 in the wild. “That makes them some of the most endangered large mammals in the world,” says Fennessy. “Giraffes have become islands in an ever-shrinking savanna.”
On the good news side, according to biologist Sam Ferreira of South African National Parks, southern giraffes are holding their own in South Africa’s national parks. Over the past five years, southern giraffe population increases have ranged from 0.1 percent in Marakele National Park to 17.9 percent in Mapungubwe National Park.
Epicenter of giraffe species
Twiga, kanyiet, tiga. Lenywa, ndwiya, iment. In the dialects of Kenya, all are words for giraffe.
“Kenya is likely the epicenter of giraffe speciation [the formation of new species],” says Fennessy. “No other country has such a diversity of giraffes.”
The animals meander through open grasslands, woodlands and scrublands. There they chew on acacias and other trees. The browsing promotes new growth, according to GCF researchers, ultimately making leaves easier to find.
Giraffes once ranged far afield in their search for food and mates. Now fragmented habitat is hampering their walkabouts. “The lack of long-distance movement limits access to suitable forage and to natural gene flow between populations,” Fennessy says.
Two giraffe species and one subspecies live in Kenya: the reticulated giraffe, which roams northern and eastern Kenya; the Masai giraffe, which inhabits the savanna and woodlands of southern Kenya; and the Nubian giraffe (formerly Rothschild’s giraffe), a subspecies of northern giraffe that’s reduced to small, scattered populations in western and central Kenya.
The Masai is Kenya’s most abundant giraffe, with some 12,000 animals, followed by the reticulated giraffe, with no more than 8,700 individuals. The Nubian giraffe numbers a paltry 400.
In the last two decades, Masai giraffes have declined by 50 percent and reticulated giraffes by some 70 percent. Nubian giraffe numbers have been going down for at least 50 years, mostly due to civil unrest in countries such as Uganda and Ethiopia, Fennessy says. “The turmoil has led to loss of giraffe habitat as people are displaced, then move into areas formerly occupied by giraffes.”
Nubian giraffes are being reintroduced in their native range, however. From east to west in Kenya, for example, small numbers are now found in Mwea National Reserve, Giraffe Centre, Kigio Wildlife Conservancy, Soysambu Conservancy and Lake Nakuru National Park, Nasolot National Reserve, Mt. Elgon National Park, Ruma National Park and Lake Baringo National Park.
Safari-goers visiting these and other protected areas can help, says Fennessy. “They can search for giraffes across the continent and let us know what they’re seeing. Many people, including guides, don’t realize that giraffes aren’t the same animals throughout Africa. When you look at the four species of giraffes alongside each other, they do in fact have different features, such as color, pattern and size.” The GCF website, https://giraffeconservation.org/, has detailed information.
It’s high time, Fennessy says, “to stick our necks out for giraffes.”