Best Time for a Tanzania Safari: The River Crossings vs Calving Season of the Great Migration in Tanzania

Tanzania is famous for its endless savannah, beautiful landscapes, and diverse wildlife. With 22 national parks, each offering a unique safari experience, Tanzania attracts visitors from around the globe throughout the year.

The Serengeti National Park is one of the most famous and popular safari destinations among visitors. In addition to the landscapes and abundant wildlife, one notable feature tops every visitor's bucket list. The chance to witness the fascinating spectacle of The Great Migration, as over two million wildebeest and hundreds of thousands of other animals, such as zebras and gazelles, move in a never-ending cycle, seeking fresh grass and water.

Have you always wanted to witness the wonder of the calving season in the vastness of the southern plains, packed and vibrantly alive, as millions of wildebeest come together to give birth almost simultaneously? Or have you always dreamed of witnessing life and death at its most elemental level; the daunting, super-charged, and perilous river crossings, where prey and predator inevitably collide? The Serengeti offers diversity on a fantastic scale, so the best time to visit will depend entirely on what you're looking to find.

The Great Migration

The Great Migration is a natural wonder of the world. Approximately two million wildebeest (also known as gnu) migrate throughout the Serengeti ecosystem of Tanzania, their route following the seasonal rainfall. Hundreds of thousands of zebras and gazelles join in the largest mammal migration on earth. Read our previous article to learn more interesting facts about the Great Wildebeest Migration.

The new year starts with the calving season in the south. Then, the herd moves north, nearing and sometimes crossing the border to Kenya, before eventually circling back to the south. The Serengeti-Mara ecosystem has sustained this cyclic migration event for millions of years. The calving season in the south and the river crossings to the north capture the attention of every visitor in the region.

The Calving Season

After a 250-day gestation on the move, almost all female wildebeest will give birth from January to March each year, when millions of them gather in the south during the calving season, primarily in the Ndutu and Ngorongoro Conservation areas. The soil in this area is rich in nutrients because of the volcanic ash left behind by eruptions. The grass that grows here is ideal for young wildebeest to build up their strength in their initial weeks of development. Each day during the calving season, thousands of wildebeest are born, giving a much-needed boost to the herd population.

The sheer numbers, peaking at around 8000 births per day, make this a splendid sight to behold. Calving usually occurs between dawn and midday, as this enables calves to have more time to gain strength and coordination before the first night, which has high predation risks. Tourists love to watch the newborn gnus wobble to their feet in just a few minutes, keeping close to their mothers for suckling and protection. But of course, there is great danger ahead, as the herd inevitably moves forward for more food and water.

More easy prey means more predators. Lions and other big cats, such as lions, leopards and cheetahs, along with spotted hyenas, black-backed jackals, and sometimes even African wild dogs are attracted to this irresistible promise of easy prey. Spectators watch as nature's stark reality plays out. Big cats group together to hunt helpless calves as their mothers try to protect their newborns. The hunt, chase, and lucky escapes of the calves guarantee a suspenseful, terrifying, and thrilling roller-coaster of emotions as you witness one of nature's greatest struggles unfold across the vast landscape. 

When and Where Can You See the Calving?

The southern Serengeti experiences short rains during the shoulder season (November and December). Thanks to the rains, the vegetation sprouts, giving way to lush pastures. The area near the Ngorongoro crater provides nutrient-rich vegetation for the young calves making it an ideal food source for the herd.

Due to the southern Serengeti's ideal environment for calving, wildebeest herds start congregating in late December on the Ndutu plains in the Southern Serengeti (officially part of the Ngorongoro Conservation Area).

The best time to witness the calving in its fullness is between late January and early March, before the wildebeest begin to move out.

The months of April and May bring the rains, providing ample grazing for the herd as they begin to make their way north. By this time, the calves become strong enough to move on, and as the grasses dry out, the wildebeest herd must embark on their migration towards the north, following the rainfall through the vast grasslands of the Serengeti.

Most of the herd will head west towards the Grumeti area first, before they arrive north, where yet another life and death struggle awaits them - the crossing of the mighty Mara River.

The River Crossings

Wildebeests have no natural leader and randomly split into small groups as they move along, some to the west and some continuing north, eventually coming together at either the Grumeti River or the Mara River.

The herd moving towards the western corridor of the Serengeti will cross the Grumeti river, and the wildebeests moving north will cross the Mara river. Many of them face both obstacles on their journey.  

As the wildebeest arrive at the riverbanks, they pile up along the river's edge. Tension ebbs and flows as their numbers mount. They are surrounded by dangerous predators, reluctant to go forward, unable to go back, with a growing urgency to take action. The actual crossing begins when a single wildebeest kick-starts the frenzy by leaping into the water. At that point, the rest of the herd blindly follows in an adrenaline-filled river crossing.

Observers will feel the rush of the stampede and hear the chaotic braying as hundreds of thousands of wildebeests attempt to cross the river in a desperate attempt to reach the other shoreline.  

This chaotic movement is a perfect hunting ground for a broad range of predators. With the big cats scouting the river banks, crocodiles lurking in the water, and vultures and marabou storks patiently waiting to scavenge the dead, the river crossing is a life-and-death struggle for the wildebeest. 

While both river crossings are fraught with peril, the crossings of the Mara River is the most dangerous of the two. In addition to the predators, which pose a significant threat, suffocation, dehydration, and the swift current add to the difficulty of the river crossing. 

Many wildebeest do not survive the Mara River crossing, but those that do make their way onwards to the border of Tanzania and into Kenya's Maasai Mara National Park, where they are rewarded with an Eden of lush green vegetation.

When and Where to See the River Crossings?

The Mara River crossings are one of the most popular attractions in Tanzania. The best time to witness the Mara River crossings is at the Kogatende area in northern Tanzania, close to the Kenyan border, during the dry season, from July through October, with the higher concentration of animals crossing in August. Take note that this time has the greatest numbers of tourists, too. The Grumeti River crossings happen in the Western Corridor of the Serengeti around late May and June. These smaller river crossings are less popular and therefore offer a less crowded view of the spectacle.

Conclusion

Every year thousands of people visit the Serengeti just to experience the natural wonder of the Great Migration, with its breathtakingly epic displays of upheaval and rebirth. The Great Migration is proof that nature is both beautiful and cruel as it inexorably strives for balance. The calving season greatly expands the herd, only to see its numbers culled during the river crossings. These two momentous events make the Great Migration in Tanzania one of the most awe-inspiring and unique spectacles on earth, and definitely deserving to be part of your bucket list.

At Sababu Safaris, we help you create your own safari itinerary based entirely on your preferences. Whether you want to go on a family safari or a solo trip, an amazing journey awaits you. Take a look at our sample itineraries to get a better idea, and feel free to contact us to learn more about Tanzania and how we can help you customize the best-possible safari experience.