Toxic weed choking flamingos to death in Rift Valley's lakes

Flamingos at Lake Bogoria National Reserve in Baringo County. [Joseph Kipsang, Standard]

From afar, the sight of thousands of flamingos spread across Lake Bogoria is magical. But on taking a closer look, you notice a big problem.

Tens of flamingo carcasses dangle from branches and thorns of Prosopis juliflora, also known as Mathenge. The scene looks like mass suicide of flamingos.

“It is worrying. Tens of flamingos died after they were trapped by Prosopis while trying to either land on the shores or take off,” Lake Bogoria senior warden James Kimaru said.

Sharp thorns

Currently, estimates from the latest water bird count in Lake Bogoria projects flamingos at 800,000, meaning the lake hosts almost half of the world's 3.5 million flamingos.

The situation being experienced in the lakes is as a result of the increasing water levels that has seen the waters rise and spill over to areas that have been ravaged by the invasive Mathenge plant.

According to Mr Kimaru, even though some of the plants have been submerged and dried up, they still pose a threat to the birds.

Mathenge is an aggressive invader that replaces native vegetation in rangelands. It is ranked among top 100 invasive species, ravaging arid and semi-arid areas of Ethiopia, Sudan Egypt, West Africa, Australia and South America among other countries. It was introduced in the 1970s to rehabilitate Arid and Semi-Arid Areas (Asals), due to its resilience and fast growth rate.

Dead Flamingos hanging on trees at Lake Bogoria National Reserve in Baringo County. [Joseph Kipsang, Standard]

However, coupled up with the increasing water levels, wetlands of international importance like Lake Bogoria are experiencing challenges.

“With the current developments, we have asked the Kenya Wildlife Service to ascertain the water quality to determine the health of these flamingos. In the long run, we will also resort to clearing part of the bushes which are killing these birds,” Kimaru said.

According to Richard Kipng’eno, a bird expert at Nature Kenya, flamingos inhabit shallow ends of the lake, a reason they crowd within the areas chocking with Mathenge plant. 

“Unlike other larger birds, their bodies are weaker and end up getting trapped because they cannot easily free themselves when trapped. Flamingos cannot inhabit deep waters and prefer the shallow end which unfortunately has been taken up by Prosopis,” Kipngeno said.

Lake Bogoria has since expanded by seven kilometre square from its original size. The swelling has resulted in submerged administration offices and the gate.

In Lake Baringo, the weed has continued to create navigation challenges along the shores, forming extensive impenetrable thickets.

“During the recent water bird counts in Lake Bogoria, there were challenges manoeuvring through some counting transects,” Kipngeno said.

Largest concentrations of the plant is in Tana River, Turkana and Baringo counties. The plant has also colonised parts of Taita Taveta, Malindi, Samburu, Isiolo, Mandera, Marsabit, Wajir, Kajiado and Migori counties.

The plant is reported to have invaded some of the important wetlands, including River Tana Delta in (Tana River County) Lorian Swamp (Isiolo/Garissa counties) and Lengurruahanga swamp (Kajiado).

Ecological disaster

The emerging ecological disaster caused by invasion of the plant on wetlands is aggravated by the increasing water levels, especially in the lakes within Rift Valley. The situation, experts say, requires urgent attention.    

The weed has also been blamed for being a cause of tooth decay in livestock. This is as a result of the animals feeding on the pods. Some locals who have been pricked by Mathenge thorns have had their limbs amputated or left nursing serious injuries.

Meanwhile, experts from Kenya Forestry Research Institute (Kefri) have been working to find solutions to the problem.

Baringo County Kefri official Simon Choge said the plant has been spreading fast and the current control methods are thinning, grinding the pods to make livestock feeds and charcoal burning from the plant.