Man, it was cold! Dense fog had formed during the night to wrap my little house on the rim of Ngorongoro Crater in a silent, gauzy blindfold. Peering through the window, I shivered, something I hadn’t expected to do so close to the equator. But then I also hadn’t expected to be living at 7,000 ft elevation ( 2,134 m). On the other hand, a fire in the fireplace was beginning to making its presence felt. Pulling up a chair to huddle near its warmth, I reviewed what I had learned from my first staff meeting as the Ngorongoro Conservation Area’s new assistant conservator (forests).
Ngorongoro’s forests and crater rim are often cold and foggy during the wet and early dry seasons. Photo by David Bygott.
Wearing a sweater to ward off the cool morning air, Henry Fosbrooke, conservator of the Ngorongoro Conservation Area, addressed the assembled officers from behind his sturdy African olive-wood desk. He confirmed that I was to oversee a large forest reserve, ten forest guards, a tree nursery, and a small fuelwood plantation of eucalyptus trees. He emphasized the need to stop livestock trespassing in the forest reserve, but he also wanted me to locate game-viewing tracks for tourists in and around Ngorongoro Crater. Then, he said something I hadn’t expected. Pausing to wipe his glasses, Henry admitted that neither activity would be possible until he obtained more vehicle fuel and a bulldozer. In the meantime I was to take over the conservation area’s rain gauge system and set up a meteorological station near the office. Also, I was informed, Richard Leakey had ordered a lorry load of bamboo for the archeological site at Oldupai Gorge; buffaloes had broken the fence around the tree plantation again; and I needed to familiarize myself with the files in my office. After the meeting, John Goddard, a Canadian wildlife biologist, and my neighbor, invited me to accompany him into the crater while he studied rhinos. Checking the fog again through the window, I decided I was in little danger of being bored. I also decided to borrow a heavy sweater from John.
In fact, I was never to be bored for long at Ngorongoro, especially when my official duties expanded to take me throughout the entire Ngorongoro Conservation Area. And, what a place it was, too!
A relief map of the Ngorongoro Conservation Area. Yellow (grassland), gray (bushland and woodland), green (forest), and brown (agriculture). Courtesy of David Bygott and Jeannette Hanby (more about them later).
Bracketed by three rift valley lakes, Manyara, Eyasi, and Natron, the Ngorongoro Conservation Area, at 3,200 sq. miles (8,300 sq. k), is nearly as large as Yellowstone National Park, which it rivals in scenic appeal and biological diversity (both are UNESCO World Heritage Sites). And how could it not what with the high peaks, plateau, and volcanic calderas of the Crater Highlands in the east, the vast sweep of the world-famous Serengeti Plains in the west, and, in the southwest, Lake Eyasi and the rugged Eyasi Escarpment (not to mention extensive areas of thorn tree bushland and woodland).
Empakaai Crater dramatically backdropped by Oldoinyo Lengai, an active volcano rising from the rift valley floor. At 10,700 ft (3,200 m) elevation and 980 ft (300 m) deep, Empakaai is highly scenic. Views from the crater rim often include Mt. Kilimanjaro 90 miles (145 km) to the east.
The Melinda grasslands, a high plateau (including the Embulbul Depression) in the rain shadow of >11,000 ft (3353 m) Loolmalison and Olosirwa mtns. The trails reflect many millennia of use by wildlife and, for at the least the last 2,000 years, livestock of a succession of pastoral peoples. The area is now grazed by Maasai livestock. The distant peak is Oldeani Mountain.
Composed of numerous species, including bamboo on Oldeani Mtn., montane evergreen forest is sustained by high rainfall, primarily on the southern and eastern flanks of the Crater Highlands. It is a major habitat for rhino, buffalo, and elephant. The pictured tree is a species of Dracaena.
Thorn tree woodland on the drier, west slope of the Crater Highlands. The dominant tree here is a species of Commiphora. This is giraffe and impala country. The eastern Serengeti Plains are visible in the distance.
Migratory wildebeest on the eastern Serengeti Plains. During my time at Ngorongoro (1964-67), approximately 400,000 wildebeest moved onto the eastern plains every wet season to graze and calve, only returning to the Serengeti National Park when the grass and water dried up. (In 1980 they numbered around 1,400,000.)
The Eyasi Escarpment rising 1300 ft (400 m) above Lake Eyasi (barely visible at far left). Shallow Lake Eyasi fluctuates widely in area both seasonally and annually. Flamingoes and waterbirds visit the lake. Agriculturalists, Hadza hunter-gatherers, and Datoga pastoralists use the adjacent semi-arid thorn bush flats.
Pretty cool, eh?
(The authors/artists Jeannette Hanby and David Bygott lived for nineteen years in Mangola Village near Lake Eyasi’s eastern shore just a few miles east of the area pictured above. Their books, Spirited Oasis: Tales from a Tanzanian Village, and Beyond the Oasis: Safaris of Song and Stone, relate their experiences during this time. Check them out at https://www.youtube.com/watch?v=MU1L-sZJs8Q; David and Jeannette tell a good story.)
(For more information on the present-day Ngorongoro Conservation Area see https://www.ncaa.go.tz/
Henry and I were enjoying the view from the veranda of the Lake Manyara Hotel. Perched atop the escarpment above Lake Manyara National Park, the hotel commanded sweeping views to the east, south, and north. The Park began almost at our feet, a jumble of trees, shrubs and rocks tumbling down a steep 1800 ft (545 m) escarpment to a narrow, irregular plain of forest, woodland, and grassland bordering the shallow muddy waters of Lake Manyara. Beyond stretched the dry, withered vastness of the Maasai Steppe, its occasional hills and dry stream beds obscured by a haze of smoke from dry-season grass fires.
Figure 1. Lake Manyara National Park begins at the top of the escarpment, extends across Lake Manyara and halfway toits distant southern tip. The building on the right is the Lake Manyara Hotel.
It was 1964. I was a newly arrived U.S. Peace Corps volunteer and Henry was Henry Fosbrooke, old Tanganyika hand and conservator, Ngorongoro Conservation Area. He was driving me to Ngorongoro where I was to take up my duties as assistant conservator (forests). While Henry finished drinking his tea, I gazed over the park. Twenty-five miles long, it was only a few miles wide, and much of this was steep, rugged escarpment. This made me wonder what was important about the park besides a striking view. “Tree-climbing lions,” Henry stated, setting down his tea cup with a forceful clink. “Unique to this park; the only place in Africa where lions climb trees.” (Note: since then, populations of tree-climbing lions have been found elsewhere, including Ngorongoro, Tarangire, and the Serengeti in Tanzania as well as Queen Elizabeth National Park in Uganda.) Beckoning for a waiter to bring the bill, he added, “There also are rather a lot of elephants.” That did it: I would visit the park the first chance I got.
Figure 2. A tree-climbing lioness in Lake Manyara National Park. (Photo by David Bygott, co-author with Jeanette Hanby of the book, Spirited Oasis:Tales from a Tanzanian village.)
Lake Manyara National Park is a good example of how the escarpments, lakes, and volcanic highlands of East Africa’s eastern rift valley have influenced the region’s biological diversity, not to mention its scenery.
At 123 sq. miles (318 sq.km), 70% of them water, the park was small. In comparison, the Serengeti National Park, 55 miles to the west, could contain 46 Lake Manyara National Parks.
Figure 3. Lake Manyara National Park includes the northern half of Lake Manyara. The Tarangire Game Reserve (now a national park) lies to the southeast, across the Great North Road.
Nonetheless, it was ecologically diverse. The combination of rocky escarpment composed of ancient basement system and younger volcanic rocks, large shallow lake, and narrow plain watered by perennial streams and springs has created habitats ranging from closed canopy forest through deciduous woodland and thicket, to open grassland and swamp. Examples of three of the most important habitats follow:
Figure 4. Elephant dreaming in a forest glade. (Photo by David Bygott.)
Forest: Fed by springs flowing from volcanic rock at the base of the escarpment, groundwater forest consists of plants that could not grow under the existing rainfall. It also contains grassy glades and swamps. The spring water originates outside the park, from rainfall falling on the forested outer slopes of the Crater Highlands thirty miles away.
Figure 5. Acacia woodland. (Photo by David Bygott.)
Acacia woodlands: haunt of tree-climbing lions. No one knows for sure why they spend so much time resting in trees. The more plausible theories include keeping away from herds of buffaloes and elephants and/or from biting flies. (Another, possibly tongue-in-cheek, suggestion is that the trees are simply easy to climb.)
This raises a question: buffaloes are the principal prey of the park’s lions, so why should lions avoid them? Buffaloes are big, mean, and hard to kill. They can put up a real fight when attacked. Consequently, Manyara lions lead harder lives than their Serengeti cousins, who frequently feast off hyena kills. This probably accounts for their desire to keep clear of buffalo herds until hunger drives them to hunt again.
Figure 6. Open grassland. (License:: Attribution-Share Alike 4.0 International [CCBY-SA 4.0]) OLYMPUS DIGITAL CAMERA
Grasslands support a large proportion of the park’s animal biomass. One of the more important types is strongly influenced by Lake Manyara in that it occurs on alkaline soils of periodically flooded mud flats. Alkali grassland fluctuates widely in area depending on the level of the lake, but is, nonetheless, heavily grazed by buffaloes, gnus, and zebras.
Large and shallow (max. depth 12 ft or 3.6 m), Manyara, like other rift valley lakes, has no outlet, losing its water only through evaporation. Therefore, its area and depth can vary significantly over time. For instance, in 1961, the lake was so dry it could be crossed in a Land Rover, whereas in 1962 rising waters killed many trees along the shore and forced zebras and wildebeests, the latter then the principal grazers on alkali grasslands, into the woodlands where they were easy prey for lions. This destroyed the wildebeest population, which took several years to return. The lake gives, but can also take away.
The varied habitats of Lake Manyara National Park provide optimal conditions for many species of wildlife: klipspringer and Kirk’s dik dik on the rocky escarpment, impala and giraffe in the woodlands, various waterbirds (at times an estimated two million) on the lake . . . However, none benefit more from this habitat diversity than elephants, which can use them all (except perhaps the lake). They can pull up tussocks of grass, forage branches up to 20 ft (6 m) high, wade into swamps to eat aquatic plants, and even carefully negotiate parts of the escarpment. Therefore, it wasn’t surprising that there were a lot of them in the park.
Figure 7. Elephant browsing an umbrella acacia (Acacia tortillis). (Photo by David Bygott.)
However, there was another, more ominous, explanation for their high numbers: hunting and loss of habitat to agriculture might be driving elephants into the park. If so, they could become so numerous as to outgrow their food supply. In such cases it’s the trees and shrubs that are most affected. If short on forage, elephants will strip bark and eat the cambium, push trees over to get at out-of-reach foliage , dig up tree roots, and gouge holes into baobab trees to access water stored in their trunks. Thus, the most visible impact of elephant overpopulation is the destruction of forests and woodlands.
Furthermore, this already was happening elsewhere. For instance, in Uganda’s Murchison Falls National Park some 1000 sq miles (2290 sq km) of woodlands would be destroyed by 1969. Worse yet, there were signs of damage to trees in Lake Manyara National Park where many Acacia tortilis (umbrella acacia) trees had been knocked down and/or stripped of their bark.
Figure 8. Elephants in the Serengeti browsing the upper branches of a fever tree (Acacia xanthophloea) they have pushed over.
This led Tanganyika National Parks to ask a young British zoologist, Iain Douglas-Hamilton, to study the situation. Iain spent the next few years identifying individual elephants and studying their behavior. He recorded what they ate and their impact on the vegetation. He learned how to age them and monitor their growth. He recorded births and when one died tried to find out why. He counted them and followed their movements. Large as they were, elephants still were hard to spot in areas of dense vegetation, so Iain immobilized a few of the big animals, fitted them with radio collars and tracked them from an airplane, which he also used to census their numbers.
Figure 9. Iain Douglas-Hamilton’s camp on the Ndala River
And, along the way, he had some exciting experiences. A partial list includes being hospitalized by an encounter with a rhino while on foot in dense bush, being swept downstream from a causeway while trying to cross a river in flood, and, on three occasions having his vehicle bashed up by elephants. As described in Among the Elephants, these incidents were scary enough to make a prospective wildlife biologist choose another career. That said, except for the rhino encounter, it was Iain’s Land Rover that sustained the most damage. Holed, ripped, bent, and lifted by angry elephants, its fenders were crumpled, roof squashed, and windows broken; the big animals sometimes pushed it around like a baby carriage. It’s a wonder the vehicle lasted through Iain’s study. Nonetheless, it did and here are some of Iain’s findings:
(a) Manyara had the densest elephant population of any park in Africa, well over 10 / sq. mile (3.0 / sq km). Elephants dominated the park’s large-mammal biomass (with buffaloes coming in a close second);
(b) Fortunately, the park’s elephants were not completely confined to the park but had access to the Marang Forest Reserve above the escarpment to the southwest. This reduced the chances, at least for the time being, of their numbers overwhelming the food supply;
(c) Nonetheless, Manyara’s elephant population still might someday outgrow their food supply, destroy their habitat, and starve.
Therefore, Iain proposed the acquisition of land owned by European farmers (many of whom were already leaving the country) at the south of the park. This would provide more room for the park’s elephants but also allow them access, across lightly settled land south of the lake, to the Tarangire Game Reserve (now national park) ten miles to the east (Fig. 3).
Over thirty years later, in 2009, Tanzania National Parks finalized this acquisition, providing hope for the future of Manyara’s elephants.
“What a view!” I yelped before snapping another photo. “Mmm, yes,” murmured Henry who had seen it many times before. While driving from Arusha to Ngorongoro we had topped the escarpment overlooking Lake Manyara (Fig. 1) and been confronted by an eye-grabbing view—steep, two to three thousand ft slopes fronting Lake Manyara and the Maasai Steppe like the ramparts of an immense fortress (Fig. 2). Wow!
Figure 1. Map of the Crater Highlands area. The Great Rift Escarpment passes west of Lake Manyara, east of the Crater Highlands (Loolmalassin Mts., Olmoti Crater etc.) and west of Lake Natron.
Figure 2. View south over Lake Manyara and along the Great Rift Escarpment. The Lake Manyara Hotel swimming pool is in the foreground.
However, I would have been even more impressed had I known this was only a small part of one of the geologic wonders of the world, a system of separate but related rift basins, composed of escarpments, and troughs some 30-40 miles wide, stretching 3,700 miles all the way from Turkey to Mozambique (Fig. 3).
Figure 3. The Great Rift Valley includes the Dead Sea and the Sea of Galilee. In Africa, it cuts through the highlands of Ethiopia before dividing into the Albertine Rift and the Eastern or Gregory Rift. Lake Manyara is in the latter. (Author: Redogeographica. Creative Commons Attribution-Share Alike 4.0 International license.)
And, it’s all caused by the earth’s crust pulling apart. In Eastern Africa, the Somali Tectonic Plate, which lies east of the Eastern or Gregory Rift (Fig. 3) is splitting away from the larger African or Nubian Plate causing huge chunks of land to sink between parallel faults (Fig. 4).
Figure 4. Parts of the rift system are not distinct valleys (Graben) but, as at lake Manyara, a single escarpment (Footwall) rising above a shallow depression (Half-Graben). (Author: Aymaith 2. Creative Common Attribution-Share Alike 3.0 Unoported License)
Geologists postulate that elevated heat flow from the earth’s mantle is causing “thermal bulges,” creating the highlands of Kenya and Ethiopia. As they form, these “bulges” stretch and fracture into a series of faults forming rift valleys. Huge chunks of land sinking between parallel fault lines force up molten rock in volcanic eruptions. Consequently, the East African Rift System (EARS), especially the Eastern or Gregory Rift, tends to be geologically active with numerous volcanoes, hot springs, geysers and earthquakes (Figs. 5 & 6).
Figure 5. Geyser at Lake Bogoria, Kenya.
The geological processes driving the formation of the East African Rift System have greatly benefited the region. For instance, rift basins with steep 2000-3,000 ft (600-900 m) escarpments, solitary volcanoes, including Kilimanjaro and Meru, and 7,000-12,000 ft (2,134-3,658 m) volcanic highlands, provide a scenic and biological diversity that otherwise would not exist (Figs. 6&7). A rough measure of this diversity is the number of Kenyan and Tanzanian national parks (16) found in areas affected by rifting and volcanism.
Figure 6. Empakaai Crater (Embargi Crater in Fig. 1), an extinct, 10,569 ft. volcano in the Crater Highlands. Beyond, Kerimasi, another inactive volcano, rises from the arid rift floor where dry season dust devils swirl among leafless thorn trees. In contrast, temperatures at Empakaai Crater are lower, rainfall higher, and morning fogs drench evergreen forests and perennial grasslands.
Figure 7. Shallow lakes typical of the Eastern Rift are well known for their flamingoes. Lake Makat, Ngorongoro Crater.
In addition, highly fertile volcanic soils support dense populations of agriculturists, as on the well-watered slopes of Mt. Kenya and Mt. Kilimanjaro (see Mt. Kilimanjaro post). Livestock productivity of rangelands occurring on volcanic soils is up to twice (or sometime more) of that on soils derived from other geological materials.
Yet another benefit is that steam from hot springs and geysers can be harnessed to create geothermal energy. In 2015, geothermal energy generated nearly half of Kenya’s electricity (Fig. 8). And, it’s green energy, too!
Figure 8. Geothermal power station at Olkaria, near Lake Naivasha, Kenya.
Then, there’s this: The East African Rift System may even have influenced human evolution. Discovery of so many remains of early hominids within the rift (Fig. 9) has led to the idea that the processes of formation of the East African Rift System (uplifts of land thousands of feet in elevation, volcanoes spewing ash into the atmosphere, extensive lava flows . . . ) may have caused frequent alternations between wet and dry periods, thereby influencing the evolution of the human species by forcing our ancestors to adapt by becoming smarter and bipedal.
And, here I’d thought it was all about the scenery.
Figure 9. Oldupai Gorge, Ngorongoro Conservation Area, Tanzania. The concrete block marks the site where the remains of an early hominid species, Zinjanthropus boisei (since renamed Paranthropus boisei) were discovered in 1959.
