DISCOVERIES | 06.21.16

March of the Flamingos

In the harsh, hot soda lakes of East Africa, flamingos thrive, and now scientists are beginning to understand how these birds live where other species die.

Story by Rachel Becker

Photographs by Paul McKenzie

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Lake Natron, Tanzania

Lake Natron, Tanzania

Paul McKenzie peered down from 500 meters above the surreal string of soda lakes that punctuate the landscape across Tanzania and Kenya. Only a loose seatbelt around the photographer’s waist kept him tethered inside the tiny plane that seemed to have had its entire right side removed for easier access. With hurricane-force winds rushing past, the sun baking the plane’s interior, and sulfurous fumes rising off the blood-red Lake Natron that stretched beneath him, McKenzie spotted a massive group of flamingos. He let out a whoop and leaned out into the wind with his camera lens trained on the birds below.

“It was like nothing I’ve seen anywhere on our planet,” says McKenzie, who has now been photographing the East African soda lakes and their avian denizens for a decade. “When I’m on my deathbed, I’ll remember those amazing experiences over the soda lakes.”

The otherworldly soda lakes McKenzie returns to year after year span the volcanic Great Rift Valley in East Africa, where the movement of tectonic plates has created shallow basins filled by rain, springs, and streams. Waters in these basins can reach 100 degrees Fahrenheit or more, and evaporation concentrates sodium, carbonate, and chloride compounds that leach from the surrounding volcanic rocks—turning the water so caustic that it will burn a person’s eyes and skin, and even disintegrate clothing in a matter of hours.

The mineral-rich waters and mud that are caustic to most other animals that venture into the soda lakes provide safe haven—and ideal breeding grounds—for the flamingos.
Even with a population that numbers in the millions, the flamingos’ inextricable link to the soda lakes makes them vulnerable to a changing climate and human activity. These factors could upset the delicate balance the birds have struck in this harsh environment.
But alkali-loving microbes thrive in these harsh conditions, staining the water the intense reds and greens that McKenzie saw from above. These same microbes sustain a population of approximately 1.5 million bright pink lesser flamingos (Phoeniconaias minor). The flamingos slurp up the algae (Arthrospira fusiformis) through their crooked beaks adapted for filter feeding. The algae in turn tint the birds’ feathers pink with the pigments they contain.

For lesser flamingos—and to a lesser extent, their larger relatives the greater flamingos (Phoenicopterus roseus)—these harsh, hot, inhospitable lakes are where they find food, mate, raise their young, and where they in turn feed other organisms that manage to live in this ecosystem.

Ken Mwathe, a Nairobi-based policy coordinator for the conservation organization BirdLife International, says the fact that lesser flamingos thrive where so few species can survive makes them special. He calls flamingos his “heartbeat,” a sentiment echoed by others whose paths they’ve crossed.

“They are about as charismatic an avian species as you can get,” McKenzie says. “It’s a triumph of evolution, a triumph of adaptation that they’ve adapted to these hostile environments.”

Lothar Krienitz, a scientist at the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Germany who studies the algae that lesser flamingos feed on, says that to visit the soda lakes and see the flamingos is to have all of one’s senses touched.

“When you are lucky and the lake is filled with hundreds of thousands of flamingos, you see only pink moving. And you hear this interesting sound, and smell natron, and feces, and decomposing algae. And the heat…” Krienitz, who recently retired, sounds wistful at the recollection. “Everybody must see it, once in a life.”

Yet even with a population that numbers in the millions, lesser flamingos’ inextricable link to the soda lakes makes them vulnerable to a changing climate and human activity. These factors could upset the delicate balance the birds have struck to be able to survive in this harsh environment. Considered “near threatened” by the International Union for Conservation of Nature, the lesser flamingo’s situation isn’t yet dire, but it is precarious.

The Mystery of the Flamingos

Despite the ardor they inspire, lesser flamingos remain mysterious. In fact, no one knew how or where this species reproduced until August, 1954, when Scottish zoologist Leslie Brown noticed that an enormous population of lesser flamingos had suddenly gone missing from a soda lake in Kenya called Lake Bogoria. Some had flown to the nearby alkaline lakes Elementeita and Nakuru in Kenya. But Brown knew that the majority of the population must have settled somewhere else.

Like Paul McKenzie more than half a century later, Brown took to the air in a tiny plane, flying south from Nairobi to Lake Natron, which stretches for about 400 square miles across the border between Kenya and Tanzania. Traveling at 100 miles per hour and trying to focus his binoculars through the turbulence, he looked down over Lake Natron and spotted what he thought had to be the missing birds: more than half a million lesser flamingos were there, and it looked like they were breeding.

Atop a crust of crystalized minerals about three miles away from the nearest shoreline, Brown saw thousands of conical mud nests that were about a foot tall by a foot wide. Each had a dimple at its peak Brown thought might be large enough to hold a single egg. Thousands of downy chicks that Brown guessed had aged past the point of needing parental care trekked by themselves or in groups across the mineral crust to drink and bathe in the freshwater springs at the base of a volcano on Natron’s southeastern shore. Frightened by the low-flying plane, one group of peripatetic chicks dove into a pile that Brown later described as looking like a rugby scrum.

Lake Natron—the breeding ground for about three quarters of the world’s population of lesser flamingos—has been threatened several times in the past decade by proposals to mine the lake for soda ash.
Brown wanted a closer look, so two weeks later he tried to cross on foot to the mineral crust island in the center of the lake. But he became trapped in the mud and sustained such bad burns on his feet from the caustic chemicals that after he crawled his way back to shore, he was restricted to bed rest for weeks.

The same caustic mud that thwarted Brown also keeps terrestrial predators, like feral dogs, hyenas, and jackals at bay, which is precisely why the flamingos nest where they do. Eggs and young flamingos don’t fare quite as well, though, against avian predators, like marabou storks, whose dour faces and habitus have inspired the nickname “undertaker birds.” The mineral-rich waters themselves also pose a threat to chicks, sometimes calcifying into shackles around their legs and slowing the little birds until they simply can’t move.

In spite of the flamingos’ relative safety from predators, they remain highly vulnerable to climate and hydrological fluctuations. Too little water, and a bridge for predators might form between the flamingos’ protective breeding island and the shore. Too much, and their island might remain submerged and the water might become too dilute to support the algae they rely upon as their primary food source. We now know that ideal breeding conditions can take a decade or more to coincide, a sizeable chunk of the lesser flamingo’s 20–40 year lifespan.

Nomads in Pink

Even though we now have a clearer picture of lesser flamingo breeding habits, we still don’t know just how many of them there are. That’s because lesser flamingos are nomadic, chasing high-density soups of their favorite algae from one soda lake to another.

In 2002 University of Leicester professor David Harper and his colleagues outfitted four adult males with satellite transmitters so they could watch the birds travel over the span of three months. This very small sample revealed a surprising degree of diversity in the population: One individual made seven visits to four different lakes, another made five visits to three lakes. The third flamingo made 44 individual trips to nine different lakes, and the fourth seems to have been eaten at the end of the first month of its journey.

This itinerant way of life makes the species exceedingly difficult to count. Current estimates suggest that some 800,000–2,000,000 lesser flamingos live in East Africa, a separate population of 15,000 to nearly 90,000 live in South Africa, fewer than 20,000 live in West Africa, and 17,000–400,000 in India.

Still, while these nomadic birds fly from lake to lake to feed, nearly all East African flamingos—which is about three quarters of the world’s population—congregate on Lake Natron to breed. This breeding ground has been threatened several times in the last decade by proposals to mine the lake for soda ash in Tanzania and to establish a hydroelectric plant upstream of Lake Natron in Kenya. Although about 32% of Tanzania’s land is preserved, Lake Natron has no specific protections beyond being considered a Wetland of International Importance by the Ramsar Convention, and an Important Bird Area by the conservation organization BirdLife International.

“Somehow, these flamingos have not only managed to survive in these conditions, they positively thrive…. It’s a triumph of evolution, a triumph of adaptation that they’ve adapted to these hostile environments.” – Paul McKenzie
“The extraction of soda ash from Lake Natron is an ongoing threat that is quiet at the moment,” explains Harper, the scientist who radio-tracked the movements of flamingos in the area. “But if it was resurrected again, that would be a serious threat.”

But Marc Baker, a Tanzanian conservationist with the organization Ecological Initiatives and the son of two ornithologists, notes that economic insecurity can also pose a threat to conservation. To protect Tanzania’s natural resources and preserve biodiversity, “We are going to have to pay for it,” Baker says. “It is just as simple as that. There is no other way.”

And Mwathe is ready to fight for the birds he loves. He says he has a “fire in my belly” about flamingos. And for anything that comes at them, “We still have our fighting gloves on.”

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ABOUT THE Author

Rachel Becker is a freelance science journalist who writes about science, the environment, health, and technology. Her work appears in

NOVA Next

,

National Geographic News

and

The Plate

,

Slate

,

Nature

,

Hakai

, and others.

ABOUT THE Photographer

In 1997, Paul McKenzie experienced his first safari in East Africa and was instantly hooked—on wildlife and wildlife photography. He is a two-time Wildlife Photographer of the Year recipient and five-time honoree of Nature’s Best. His images have been published in

The New York Times, Time magazine,

and

BBC Wildlife magazine

, among others.

Rachel Becker
Paul McKenzie

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