The Great Wildebeest Migration is a remarkable natural phenomenon involving the year-round, cyclical movement of over 1.5 million wildebeest, accompanied by hundreds of thousands of zebras and gazelles, across the vast Serengeti-Mara ecosystem of Tanzania and Kenya.
Driven by instinct and survival, these herds follow the rains searching for fresh grazing and water, moving from one region to another as seasons shift. This nomadic journey spans hundreds of kilometers and touches various iconic areas including the Serengeti National Park, Ngorongoro Conservation Area, and the Maasai Mara.
Within this broader migration, one of the most dramatic and visually striking events is the wildebeest river crossings. These crossings are not constant throughout the year but occur at specific times when the herds must cross major rivers like the Grumeti and the Mara. It is during these moments that the migration becomes particularly perilous.
Wildebeest plunge into muddy, fast-flowing waters teeming with crocodiles, while predators such as lions and hyenas wait on the other side turning the crossings into life-and-death trials. These river crossings are brief, intense spectacles of nature’s raw drama, offering a thrilling contrast to the otherwise steady rhythm of the great migration. Together, they define the epic story of survival in the African savannah.
Northward wildebeest migration versus Southward wildebeest migration
The wildebeest migration in the Serengeti-Maasai Mara ecosystem follows a cyclical pattern, divided into two key phases: the northward migration and the southward migration. The northward migration takes place from March to August, with large herds traveling from the southern Serengeti to the Maasai Mara in search of fresh grazing.
During this time, dramatic river crossings, particularly at the Mara and Grumeti Rivers, attract much attention. The perilous crossings, teeming with crocodiles and predators, create thrilling spectacles that captivate wildlife enthusiasts.
In contrast, the southward migration, from September to February, is a quieter phase. Wildebeests return to the Serengeti for calving, and although river crossings do occur, they are less intense, making the spectacle less visually captivating but equally important for the survival of the species.
Major Wildebeest River Crossings versus Minor Wildebeest River Crossings
In the Maasai Mara–Serengeti ecosystem, wildebeest river crossings are categorized into major and minor based on scale and intensity. Major crossings involve the Mara River—on both the Maasai Mara (Kenya) and Serengeti (Tanzania) sides—and the Grumeti River in Western Serengeti. These are dramatic, large-scale events where thousands of wildebeests plunge into crocodile-infested waters, attracting predators and tourists alike.
In contrast, minor crossings occur at less intense points such as the Sand River, Seronera River, parts of Lake Ndutu, and the Mbalageti River. While still risky and essential to the migration route, these crossings are smaller in scale and may involve smaller herds at a given, offering subtler but equally fascinating moments in the great migration journey.
Major River Crossings
Grumeti River crossing (Serengeti, Tanzania) – May to June
The Grumeti River, located in the western corridor of Serengeti National Park, flows westward before joining the Mara River system heading to Lake Victoria. Wildebeests encounter this river for the first time during their northward migration between May and June, depending on the rainfall patterns.
While the crossing can be dangerous, it is generally considered less dramatic compared to the other major river crossings in the migration. This is due to several factors: the smaller scale of the crossings, lower danger level, and the river’s narrower width compared to others like the Mara River.
While large Nile crocodiles lurk in the water, their presence is less intimidating here, and the river’s gentler banks make escape easier for the wildebeests. Although the wildebeests do face challenges such as steep, muddy banks and potential drowning, the overall danger is less extreme than at other crossing points. During their southward migration from October to early November, wildebeests cross the river again as they return to the southern Serengeti plains.
Mara River crossing (Serengeti side, Tanzania) – June to July
The Mara River crossing on the Serengeti side is considered the second-best river crossing, with the more dramatic crossing on the Maasai Mara side taking the top spot. Wildebeests typically make their first crossing of the Mara River on the Serengeti side between late June and early July during their northward migration. They cross the river again during their southward movement from October to early November as they return to the Serengeti.
Though the Mara River crossing on the Serengeti side is less dramatic than the Maasai Mara side, it remains an attractive experience due to its more intimate setting, fewer crowds, and stunning views of the rolling plains. The Serengeti side offers the unique opportunity to witness the early stages of the crossing, providing close-up views of wildebeests as they navigate the river, avoiding crocodile attacks and strong currents.
The crossing here is considered less dangerous compared to the Maasai Mara side, making it a memorable and peaceful alternative for travellers seeking a more serene perspective of the migration river crossing. Its good accessibility and lower tourist numbers add to the appeal.
Mara River crossing (Maasai Mara side, Kenya) – July to August
The Mara River flows through the Maasai Mara National Reserve in southwestern Kenya, forming the border between Kenya and Tanzania. It runs from the western edge of the Maasai Mara and winds through northern Serengeti, carving dramatic valleys and providing water for wildlife throughout the year. The Mara River originates from the Mau Escarpment in Kenya flows southwards, then turns west and north into the Mara-Serengeti ecosystem.
The wildebeests usually make their first major river crossing around July as they move northward from the Serengeti into the Maasai Mara. This crossing is famous for its dramatic scenes, where thousands of wildebeests risk their lives to reach the lush grazing grounds of the Mara.
The wildebeests face significant dangers during the crossing, including the threat of crocodiles lurking in the river, as well as strong currents and fast-moving waters. Additionally, lions and other predators often wait on the riverbanks, making it even more perilous.
For many travelers, watching the wildebeest crossing is the highlight of a safari. The sheer number of animals, combined with the suspense of their journey, creates an unforgettable spectacle. Watching the crossing is an intense, heart-pounding spectacle as thousands gather at the river’s edge, hesitating for hours before one finally leaps, triggering a thunderous, chaotic charge.
Wildebeests often mill around nervously before suddenly surging forward; dust clouds, splashing water, thundering hooves, and hesitant herds crowding the banks make the experience intense and emotional.
The Kenyan side of the Mara River is favoured by most travelers for several reasons. First, it offers better accessibility, with well-maintained roads leading directly to key crossing points. The dramatic landscape surrounding the river enhances the viewing experience, with wide, open plains and natural viewing platforms. Close proximity of viewing points allows guests to witness the wildebeest crossings from spectacular vantage points, ensuring incredible photo opportunities.
Additionally, the Kenyan side tends to have more frequent crossings due to the wildebeests’ migration patterns. Its easier accessibility and variety of accommodations make it the most convenient and popular choice for safari-goers.
Wildebeests cross the Mara River again during their southward return to the Serengeti, usually around October to November. To many, this crossing epitomizes the Great Migration, symbolizing nature’s most dramatic and awe-inspiring event.
Minor River Crossings
Sand River (Maasai Mara, Kenya) – June to July
The Sand River runs along the southern edge of the Masai Mara National Reserve in southwest Kenya, near the border with Serengeti National Park in Tanzania. As a tributary of the Mara River, it plays a role in the migration journey of wildebeests.
While less dramatic than the Mara River—due to gentler banks and fewer crocodiles—the Sand River offers spectacular sightings, especially when large herds cross during the northward migration around June to July.
Some wildebeests also cross back during the southward migration between October and early November, but the main and most impressive movement occurs during their entry into Kenya.
Seronera River (Serengeti, Tanzania) – April to June
The Seronera River is located in the central Serengeti region of Tanzania, an area known as the Seronera Valley. This river plays a crucial role during the northward migration of wildebeests, providing essential water and grazing along their journey.
Wildebeests typically cross or pass near the Seronera River between April and June, depending on rainfall patterns. During the southward migration, wildebeests cross the Seronera River between October and November as they return from the Maasai Mara to the southern Serengeti for calving.
Though not as dramatic as larger crossings, Seronera offers excellent game viewing during this movement due to its high predator and wildlife concentration.
Lake Ndutu and the southern Serengeti plains - calving grounds
Lake Ndutu is located in the southern Serengeti, near the Ndutu plains in Tanzania. It plays a critical role in the wildebeest migration, particularly during the southward movement.
Wildebeests typically cross the lake as they head back to the southern Serengeti from the Maasai Mara between October and November. This crossing marks one of the final obstacles in their migration cycle before reaching the calving grounds in the southern plains.
Giving birth brings an end to the migration cycle, after which the wildebeests begin their northward migration, renewing the cycle once again. Therefore, Lake Ndutu is vital for both the conclusion and renewal of the migration.
Mbalageti River (Western Serengeti, Tanzania) – April to May
The Mbalageti River flows through the western corridor of Serengeti National Park, running toward Lake Victoria. It plays a significant role during the northward migration, as wildebeests and their newborn calves begin their long journey from the southern plains.
The crossing typically occurs between April and May, following the calving season in January and February. The Mbalageti River is often the first river that newborn calves encounter, making it a crucial test of endurance and survival.
While not as dramatic as other crossings, it marks the beginning of the calves’ migration journey which is a key transition point in the migration cycle.
Wildebeest’s mating season - the rut and wildebeest’s calving season
The wildebeests’ mating season, also known as the rut, takes place from mid-May to early July, shortly after the rainy season when the animals are in peak physical condition. This timing ensures strong, healthy offspring for the next generation.
The mating occurs while the herds are moving through the western and central Serengeti. In contrast, the calving season happens between January and February in the Southern Serengeti, particularly around the Ndutu plains.
During this time, hundreds of thousands of calves are born almost simultaneously, attracting predators and offering one of the most dramatic wildlife spectacles of the migration cycle.
The best time to witness wildebeest migration and calving
Grumeti River crossing – 15th of May to 16th of June
Mara River crossing (Maasai Mara) – 20th of July to 15th of August
Wildebeest’s calving season – 15th January to 15th February
Going on an African safari is an adventure of a lifetime. If you’re after the great migration safari, we have detailed information on this, making it easy to plan around. However, if you require more details, need an itinerary or plan with us, you can contact us or request a callback.
Happy safari!
