Overview

The Grumeti River flows in a westerly movement across the top half of the Serengeti National Park before emptying into Lake Victoria. The Upper Grumeti refers to the section of the river that cuts across the Northern Serengeti, as opposed to the Lower Grumeti, which flows through the Western Serengeti. Two distinct types of woodlands are found in the Upper Grumeti area; a lush gallery forest shades the river banks while acacia woodlands flourish throughout the valleys and hills. Both of these two distinct habitats play host to unique flora and fauna that will be discussed in more detail below.

Ecosystem

As mentioned above, a distinctive gallery forest lines the banks of the Grumeti River. This lush habitat includes unique species such as fig, mahogany, date palm, and tamarind trees. Large groups of hippos can be seen bobbing and splashing in the dark river waters. The neighboring forest is also home to playful vervet monkeys and large groups of inquisitive baboons. The occasional colobus monkey has also been noted, although this species of primate is more commonly seen along the Lower Grumeti.

The Grumeti River is a seasonal river and only flows during certain times of year, though deep pools of water remain year round supporting the resident hippos and crocodiles. In the treetops of the gallery forest live brightly colored birds of the turaco family, especially Hartlaub's and Ross's, which are vivid green and blue with crimson wings. In addition to their distinctive markings, the turaco family is also noted by their harsh call and quirky habits of running and hopping along the branches and trees. Along the riverbank several species of kingfisher are likely to be seen flitting about, showing off their shiny feathers and vibrant colors. Also commonly seen is the majestic fish eagle which resembles a bald eagle, and whose lonely cry will often be heard echoing above the riverine forest.

The surrounding area (approximately 10 miles on either side of the river) is covered in verdant woodlands consisting mainly of acacia tree species such as whistling thorn, paper-bark, green thorn and flood-plain acacia. These acacia woodlands support a myriad of herbivores including elephant, Thomson's gazelle, topi and buffalo. Of particular note worthy interest are the large groups of impala and giraffe that can be seen in this region. Africa's great predators also lurk in the shadows of these shady woodlands. All three majestic species of big cats are present here including leopard, lion and cheetah. Although common in other areas of the Serengeti, the spotted hyena is relatively rare in these woodlands.

Wildlife

Giraffe in particular seem to dominate Upper Grumeti Woodlands as they feed exclusively on the tender leaves of acacia trees, which happen to flourish here. The species occurring in the Serengeti is the Maasai giraffe. Since giraffe do not compete for food with grazing animals, and barely overlap browsing zones with other browsers because of the height at which they feed, they are able to share their habitat with a wide range of animals.

Although normally elegant in stature and graceful in movement, Giraffe have difficulty in bringing their heads down to ground level, so when drinking they have to splay their forelegs out sideways in a rather awkward looking position. A mature male giraffe weighs about 2,200 pounds and stands approximately 11 feet at the shoulders. For all its great length the giraffe's neck has only seven vertebrae, as in man. Twiga, as the giraffe is known in Swahili, is the national emblem of Tanzania.

Woodlands

It is interesting to note the various self defense mechanisms exemplified throughout the Upper Grumeti Woodlands. From the tree's point of view, all vegetarians are enemies that the trees try to repel in order to minimize their own destruction. For example, acacia trees have evolved long prickly thorns to help defend themselves against browsers. Some species of acacia have poisonous sap, which is triggered when the leaves are being consumed. This is evident in watching giraffe as they rarely browse a single acacia tree very long before moving on.

The whistling thorn tree has an ingenious defense against browsers. This scrawny acacia produces hollow back swellings or 'galls' at the base of its thorns. They provide ideal apartments for a certain kind of ant, which only has to gnaw entry holes. The name 'whistling thorn' comes from the sound made by the wind blowing across the holes. The tree even secrets droplets of sweet fluid for the ants. In return, the ants defend the tree by attacking anything that tries to eat its leaves.

Grumeti Game Loop

One of the best game drives in the Northern Serengeti is called the Grumeti Game Loop. This is a 'U' shaped game loop that diverges from the main road at Lobo and heads northwest to Grumeti River and Migration Tented Lodge. The game loop track then parallels the Grumeti River for several miles before heading back southeast to the main road at Lobo. The game drive takes about 2-hours to complete and can be very rewarding. If staying at Migration Tented Lodge, this game loop also functions as the entrance road so you will undoubtedly game drive this loop on several occasions. Animals regularly encountered on this game loop include giraffe, impala, Thomson's gazelle and buffalo. Lions are frequently sighted here and also the occasional cheetah.

There is a large lion pride that seems to use the road here to hunt and travel. On several occasions we have seen lion kills just feet from the road. During the dry season, a constant stream of migratory wildebeest and zebra can be seen flooding through the woodlands as they continue their epic journey in search of food and water.

Great Migration

The legendary wildebeest migration thunders through the Upper Grumeti River Woodlands twice a year including July and August (during the northward migration) and September through November (during the southward migration.) The southward wildebeest migration is much more pronounced than the northward migration in this area since the animals seem to linger for longer periods of time on their southern journey. Throughout the dry season one can usually see a few scattered herds of migratory wildebeest even when the main masses have moved on.