The discovery of a noxious alien invasive weed along parts of Mara River and the Maasai Mara Game Reserve poses serious threats to the annual migration of more than a million animals in the Serengeti ecosystem. Parthenium (Parthenium hysterophorus) commonly known as Feverfew or Whitetop is considered one of the world’s most dangerous plants. It produces chemicals that prevent other plant growth and is toxic to animals. It can choke all grazing land as well as food crops such as sorghum and millet and is toxic to humans.

This alien affront to the Mara/Serengeti wilderness comes at time when this fabled ecosystem is already under attack from poaching, land conversion, fencing, disease and fires, not to mention the now thorny issue of building a major highway right through the Serengeti National Reserve effectively cutting off the annual wildebeest migration.

Earlier this month, The East African Wild Life Society issued a distressed press release seeking the intervention of the governments of Tanzania and Kenya to nip this invasion at the bud.

“We are seriously concerned about these alarming reports and urge the authorities in Tanzania and Kenya to investigate and take whatever action is necessary before it is too late,” said EAWLS Executive Director, Nigel Hunter.

The weed was detected during a recent survey along the banks of the Mara River, sparking concern among scientific and conservation bodies because of its ability to choke other plants on which animals graze. Wildlife will only eat the plant if all other grazing disappears, ignoring a fatal risk of poisoning.

The plant originated in the Americas but spread to Australia and Asia before reaching Ethiopia and Uganda. It is now threatening one of the most important savannah ecosystems in Africa – and the world.

Anne Witt, Invasive Species Co-ordinator at the Centre for Agricultural Bioscience International (Cabi), has published a comprehensive look into this unwanted alien in the second issue of SWARA 2011 (SWARA 2011:2) coming out next month.