Entries in migrations (3)


Extreme Animal Migrations

We humans are not the only ones that enjoy a trip abroad. Some animal species migrate to find food, breed, or escape the cold. There are a few species, however, that take this journey to the extreme.

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Great Migrations of the Animal Kingdom: Part Three

In the third and final part of this week’s look at incredible animal journeys, it is today the turn of those down to earth creatures with their feet firmly on the ground, as Frontier considers terrestrial migrations of the animal world.

Wildebeest - Southern Serengei (Tanzania) to Masai Mara (Kenya)

No feature on great animal migrations could be complete without looking at this amazing spectacle made famous by countless natural history documentaries and wildlife photographers. Everyone is familiar with images of this mass movement, which often focus on the various predators gorging themselves as the millions of wildebeest make their annual voyage.

The migration begins in the lush, short grasses of the southern Serengeti, where the herds gather in November. It is here that the animals calve, giving birth to their young at the beginning of February. The heard remain in this location until around April, leaving only when the calves have gained enough strength for the journey ahead. This period sees many predators taking advantage of the vulnerable calves. As the long rains move westwards through the central Serengeti, the wildebeest head north-west in search of the fresh pastures these rains bring. This brings them into the Western corridor and towards the Grumeti River, the crossing of which in June brings about the herd's first contact with the well-documented crocodiles lying in wait for their arrival. July sees the drying of the grasslands, forcing the herds to move north in search of food. The wildebeest will face another croc-infested river crossing as they head for the grasses of the Masai Mara throughout August and September. After grazing in the lush Mara grasslands, the herds eventually begin to move south again during late October and November. A final crossing of the perilous Mara River is made en route to the southern short-grass plains of the southern-Serengeti where the cycle begins once more.        

Christmas Island Red Crabs – Forest to Coast

Despite their association with the sea, the annual migration of red crabs on Christmas Island is very much a terrestrial affair. Like all of the migrations covered in this feature, this must be an incredible thing to witness. At some point during October and November, approximately 120 million adult red crabs begin an amazing journey from the forests in which they normally reside. Streams of crabs must climb down steep inland cliffs to reach their destination. Having reached the coast, these adult crabs mate and release eggs into the sea. Each female lays approximately 120,000 fertilized eggs. After about a month in the sea, the eggs develop through various larval stages, before eventually forming into tiny crabs. The surviving individuals then move onto land and begin their journey back to the island’s inland forest.

By Alex Prior


Great Migrations of the Animal Kingdom

This week we’re looking at some of the most incredible mass migrations in the natural world. With so many amazing journeys to choose from, deciding which ones to explore was far from easy.

Kicking things off today with the marine world, be sure to stay tuned this week to learn more about some of the most iconic and awe-inspiring voyages undertaken by land and air.

Pacific Salmon Run – North America and Canada
All five species of Pacific salmon migrate between freshwater and saltwater during their life cycle. Having made the journey from the freshwater streams in which they are born to the sea, they then return to these freshwater sites to lay their own eggs. Different ‘runs’ exist within the different species of Pacific salmon, with the Adams River sockeye run being one of the most famous. During their strenuous and lengthy spawning mission, the salmon face many different dangers, such as starvation (they do not feed once they leave their saltwater habitat) and hunting by humans, bears, otters and eagles. Man-made dams are increasingly posing a problem to the salmon. As if this was not enough to contend with, the salmon then fight one-another once they arrive at the breeding grounds.

Sardine Run – Southern Africa
This annual extravaganza is one of nature’s most impressive spectacles. The ‘run’ begins in the cool waters south of the African continent, where large shoals of sardines form before moving north into the warmer waters of the Indian Ocean. This mass migration of hundreds of millions of sardines is brought about by the movement of their main food source, plankton. As a cold-water current moves to the north, the sardines have no choice but to follow. This in turn attracts a vast array of predators to the area such as dolphins, sharks, sea birds and the immense Bryde’s whale, creating what has been dubbed ‘the greatest shoal on Earth’. The BBC’s incredible footage of the phenomenon is a truly amazing watch.

By Alex Prior