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Naivasha Virtual Fieldcourse

Lakeshore birds

 

Lake Naivasha's extensive riparian fringe hosts a great variety of birds. Many forage on fish and insects living within the lake shallow littoral waters and among the papyrus. Others, such as the majestic African fish eagle (Haliaeetus vocifer) build their nests on the tall Acacia trees (Vachellia xanthophloea) at the lake edge. The call of the fish eagle has a distinctive charm that accompanies Naivasha's sunrise each early morning. The bird calls typically swinging its head back and forth. Eagles prey on fish by swooping down to the water surface and stabbing a surface-swimming individual with formidable claws. An adult eagle is capable of snatching a 1 kg catfish or carp, but they may attack other water birds (ducks, flamingos) too, or steal prey from large waders like Goliath heron (Ardea goliath) or Saddle-billed stork (Ephippiorhynchus senegalensis).

Endangered species include tall and elegant Grey Crowned Crane (Balearica regulorum), present only in parts of eastern and southern Africa, who reproduce at the lake shore but whose chicks are highly vulnerable to attacks by a variety of predators. During the reproductive season, male cranes jump on both legs around the female trying to perform their famous mating dance (not always as elegant a performance as you may imagine!).

A less well-known endangered species, rarely seen on the lake shore at Naivasha, is the secretive Basra Reed Warbler (Acrocephalus griseldis), originating from the central and southern marshlands of Iraq, which migrates regularly to East Africa during the northern hemisphere winter season. The drainage of the Euphrates/Tigri marshes deprived this species of 80% of its homerange, with a 20% consequent reduction per decade in species counts done in Kenya. After 2003 and the return of planned inundations, the Basra warbler became considered the flagship species indicating the recovery of the mesopotamian marshes. It feeds on a variety of insects and tends to build nests 1.6 m above water, tied onto Typha or in Phragmitis stems. Despite beneficial reflooding, pollution due to oil mining and energy production are still threatening the warbler survival.

As illustrated by this last case, Naivasha serves as refuge for a multitude of over-wintering bird populations; this is why it has been designated under the Ramsar Convention for the protection of wetlands of international importance.

Basra Reed Warbler on display on reed in the Iraqi marshes; a: male, b: female.

[Source: Omar F. Al-Sheikhly, Iyad Nader & Filippo Barbanera (2013) Breeding ecology of the Basra Reed Warbler, Acrocephalus griseldis, in Iraq (Aves: Passeriformes: Acrocephalidae). Zoology in the Middle East 59 (2):107-117.]