The lost migrations of the Liuwa
The lost migrations of the Liuwa
BY : DR. MATTHEW BECKER - Zambian Carnivore Programme
Few sights in nature are as stirring as the thundering herds, the noise, dust and dung of the large African mammal migrations - and the attendant predators in tow. Sadly, however, future generations may not be as fortunate to witness the sights, sounds and spectacle of these events, nor enjoy the myriad ecological and economic benefits they provide.
A recent paper in the journal Science chronicled the collapse of the world’s large herbivore populations, and nowhere was it more rapid and widespread than in Africa, where burgeoning human populations and demands on land and wildlife continue to stretch the continent’s resources.
Of all the large herbivores, the wildebeest perhaps best embodies the plight of the continent’s great herd animals. Heavily poached for bushmeat and impacted into migration corridors by human encroachment, wildebeest have suffered steep declines throughout Africa. While the Serengeti migrations are the best known, there are a number of other places less dramatic but still key strongholds for this fascinating but sensitive species.
Very little is known about Zambia’s wildebeest. From the small, isolated populations of Cookson’s wildebeest in the Luangwa Valley (the largest and lightest of the blue wildebeest subspecies), across to the great Busanga Plains of Kafue, and finally to the endless expanses of Liuwa Plain, wildebeest are an important presence throughout Zambia’s ecosystems.
The seasonally flooded grasslands of Western Zambia’s Liuwa Plain host what is thought to be Africa’s second-largest wildebeest migration, and supported rich concentrations of game before the decades-long Angolan civil war decimated them. Believed to historically migrate between Angola and Zambia, the wildebeest range helped delineate the boundaries for the Liuwa-MussumaTransfrontier Conservation Area spanning the two countries.
With an array of ecological impacts through their grazing and movements, and as the primary food source for all of Liuwa’s carnivores, the wildebeest is undoubtedly the keystone species for the ecosystem. But unlike the Serengeti, where studies have occurred for decades, very little is known about Liuwa’s wildebeest, other than that their populations grew dramatically under the increased protection of the public-private management partnership between the African Parks Network, Zambia Wildlife Authority, and the Barotse Royal Establishment.
And like every protected area network, Liuwa is experiencing rapid human and ecological change, particularly as the ecosystem is restored, necessitating accurate and current information to guide conservation efforts. In 2012 the Zambian Carnivore Programme, APN, ZAWA and World Wide Fund for Nature embarked on an intensive long-term study of Liuwa’s wildebeest in an effort to determine factors limiting their recovery.
The study maintains 40-50 radio-collared adult cows which are closely studied year-round in Greater Liuwa by a full-time team of researchers logging hundreds of days in the field. These animals form the basis for investigations aimed at determining survival, reproduction, mortality and movements. These data, combined with ongoing large carnivore studies and studies of human encroachment and poaching impacts, help to address threats and assist management of this critical species.
While the first years of data are currently being analysed, preliminary findings indicate several key factors affecting wildebeest recovery, most notably predation and human impacts. Not surprisingly, the wildebeest increase has been tracked by the abundant spotted hyaena population in Liuwa, which has thrived in the absence of a significant lion population.
Concurrent studies of Liuwa’s predators indicate a high survival rate of Liuwa’s hyaena (based on 245 individuals from 6 clans), and a strong impact of predation on wildebeest, particularly in the wet season when herds reside among the dense hyaena populations of southern Liuwa Plain.
While such dynamics are natural and to be expected as the ecosytem recovers, on the human side rapid land conversion in the corridor areas outside the Park, coupled with a burgeoning bushmeat trade in the region, are likely to severely impact wildebeest recovery through poaching, disturbance, and habitat loss.
The results are sobering as currently no wildebeest have been documented migrating into Angola as originally thought, and conversion of dry season range outside the Park into rice fields means that urgent attention is needed to protect areas outside the park in the rest of the Greater Liuwa to retain some hope of restoring one of Africa’s great migrations to its former splendour.
There is a lot of work to be done to ensure recovery of the wildebeest, in Liuwa in particular and Zambia in general. One of the best things we can do as individuals is to support wildlife-based tourism in any of the ecosystems where wildebeest can still be found, and thus support increased protection of their range, for now and for future generations to enjoy.