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Gentle giants: Understanding of giraffes just doesn’t measure up

OKAVANGO DELTA, Botswana – For the tallest animals on earth, giraffes can be awfully easy to overlook. Their ochered flagstone fur and arboreal proportions blend in seamlessly with the acacia trees on which they tirelessly forage, and they’re as quiet as trees, too: no whinnies, growls, trumpets or howls. “Giraffes are basically mute,” said Kerryn Carter, a zoologist at the University of Queensland in Australia. “A snort is the only sound I’ve heard.”

Yet watch giraffes make their stately cortege across the open landscape and their grandeur is operatic, every dip and weave and pendulum swing an aria embodied.

To giraffe researchers, the paradox of this keystone African herbivore goes beyond questions of its camouflaging coat. Giraffes may be popular, they said – a staple of zoos, corporate logos and the plush toy industry – but until recently almost nobody studied giraffes in the field.

“When I first became interested in giraffes in 2008 and started looking through the scientific literature, I was really surprised to see how little had been done,” said Megan Strauss, who studies evolution and behavior at the University of Minnesota. “It was amazing that something as well known as the giraffe could be so little studied.”

Giraffes are the “forgotten megafauna,” said Julian Fennessy, a giraffe researcher and executive director of the Giraffe Conservation Foundation. “You hear all about elephants, Jane Goodall and her chimpanzees, Dian Fossey and her mountain gorillas, but there’s been a massive paucity of information about giraffes.”

Now all that is changing fast, as researchers seek to understand the spectacular biology and surprisingly complex behavior of what Fennessy calls a “gentle giant and the world’s most graceful animal.” Scientists have lately discovered that giraffes are not the social dullards or indifferent parents they were reputed to be, but instead have much in common with another charismatic mega-herbivore, the famously gregarious elephant. Female giraffes, for example, have been found to form close friendships with one another that can last for years, while mother giraffes have displayed signs of persistent grief after losing their calves to lions.

“Giraffes have been underestimated, even thought of as a bit stupid,” said Zoe Muller, a wildlife biologist at the University of Warwick in England. But through advances in satellite and aerial tracking technology, improved hormonal tests and DNA fingerprinting methods to extract maximum data from giraffe scat, saliva and hair, and a more statistically rigorous approach to analyzing giraffe interactions, she said, “we’ve been able to map out their social structure and relationships in a much more sophisticated way; there’s a lot more going on than we appreciated.”

Giraffes are found throughout sub-Saharan Africa, currently classified as a single species with up to nine subspecies that differ by features like head shape and whether the fur on their legs is plain or patterned. The species is not listed as endangered, but researchers point with alarm to evidence that in the past 15 years, the giraffe population has plummeted some 40 percent, to less than 80,000 from 140,000.

Researchers also emphasize the ecological importance of giraffes. “As large browsers, they’re habitat changers,” Fennessy said. “They spend a hell of a lot of time feeding, pruning, distributing seeds across the landscape, keeping the habitat open for other wildlife to use.” By going from tree to tree and blossom to blossom, he added, they even serve as pollinators.

Carter and her colleagues followed more than 400 giraffes for six years, identifying their home ranges and who associated with whom. As the researchers reported in the journal Animal Behaviour, the females displayed clear and persistent social preferences. Some giraffes with overlapping home territories would never be found together, while others were sighted associating a good 80 percent of the time.

Female giraffes can live 20 years or more, Carter said, and it makes sense they might rely on each other for clues to the best feeding grounds or help with calf caretaking. Or perhaps to console each other. Giraffe calves are extremely vulnerable to predators, and though mothers will fight valiantly to keep their young alive, half or more of all calves are killed in their first year of life.

Also of interest is the giraffe’s exceptional cardiovascular system. A large giraffe can stand 20 feet tall, with its neck accounting for roughly a third of its span and its long legs the same. The multitiered challenge, then, is how to both pump blood very high and retrieve it from far below while avoiding burst capillaries in the brain or blood pooling around the hooves.

As part of the Danish Cardiovascular Giraffe Research Program, scientists have traveled to South Africa to study giraffe physiology. They have measured blood pressure and found readings that range from high to ridiculous – up to five times human blood pressure. The giraffe has extremely thick blood vessel walls to prevent blood from leaking into surrounding tissue, while rugged, inflexible collagen fibers in its neck and legs help keep the blood traffic moving. A complex mesh of capillaries and valves store and release blood in the neck, allowing the giraffe to bend over for a drink of water and then raise its head again quickly without fainting.