The Western Corridor is the hotspot in late June and July as the wildebeest migration rolls into town, but it also retains a sizeable resident population of wildebeest - and good general game viewing - year round. This is a funnel shaped piece of land running from the Central Serengeti west to the park boundary near the shore of Lake Victoria. It's an interesting and beautiful area, particularly when you leave the main road - and the Peugot 504 taxis - behind.
Ranges of hills including the Nyamuma and Simiti Hills run east to west forming a high sided corridor. The Mbalageti River to the south and Grumeti River to the north drain the area towards Lake Victoria. Within the corridor are vast flat plains framed by the ranges of hills, Nyamuma and Musabi on the eastern end of the corridor, Ruana to the north, bordering Ikorongo and Ndabaka to the west running up to the shores of Lake Victoria. These plains are totally different in character to the southern plains, dotted with numerous patches of woodland and river lines, with the Grumeti River forming a backbone around which much of the game activity revolves. The soil is quite different, with black cotton instead of lava ash, so as you'd expect the grasses which grow here are different species - many of them appearing much softer than the grasses which you find further south. In many places where there is poor drainage, the plains are covered in patches of whistling thorn acacia and dotted with solitary balanites and acacia trees.
The western corridor is one of the spots where the migrating animals are forced to cross a river, in this instance The Grumeti River. The time when this happens is after the animals leave the southern plains and begin heading north and west, which is usually July. By the late dry season the Grumeti dries up into a series of pools, but after a good rainy season the river can be still be fast flowing and a serious hazard to the migrating animals. Actually seeing a crossing is largely a matter of luck. However, even if you don't find a crossing there are many opportunities to get into the middle of seriously large herds of animals. They often gather in the mid mornings around waterholes in such densities that they look like ants swarming round a nest.
Throughout the dry season, sporadic thunderstorms near Lake Victoria produce enough rain to keep certain parts of the area green. As a result there is a large herd of resident wildebeest numbering some 50,000 (not always in one cohesive group) which remain in the western corridor rather than joining the rest of the migration in heading north.
Besides the wildebeest there are numerous other resident species and they are drawn regularly to the river and tributaries to drink. Here, as usual, the lion wait in ambush. The Grumeti River is also a good place to find large pods of hippos and some good sized crocodiles. There's good bird life along the river as described in the upper reaches near Lobo in the Northern Serengeti and strangely the only place in northern Tanzania where you stand half a chance of spying Patas Monkeys gamboling in the riverine forest.
In late June and throughout July the game is an excellent reason for being in this part of the Serengeti. It is though becoming increasingly hard to offer a true wilderness experience here and outside of these times our own preference would be to concentrate in the far northern Serengeti, around Kogatende (any time of year but particularly mid July to late October) or during the Green months (Dec to April) on the southern Plains around Ndutu and beyond.
It's also worth noting that there are some bad tsetse areas within this central band of acacia woodland, stretching from north of Seronera to Ndabaka in the west. Concentrations vary a lot according to the prevailing weather, specific vegetation and amount of game around amongst other things. Traditionally this has represented minimal inconvenience to travellers in the western corridor, with any minor irritation being far outweighed by the plus points of the area. Recently however we have received reports of some spots being particularly bad. We're not yet sure whether this is just a particularly bad clash of conditions or something more than that so for now we're simply flagging up the potential for encountering tsetse to minimise any nasty surprises.