Earlier this year, it was predicted that the Okavango floodwaters would reach Lake Xau at the end of the Boteti River. By September, the water had already flowed under the bridge near Mopipi, and it finally reached Lake Xau on 16th October. Pete Hancock was there to witness this momentous occasion.
The Boteti River near Mopipi during September 2009 (top) and 2010 (bottom) (Photos: P Hancock)
In an area where ambient temperatures soar above 40 degrees, and the grass is so desiccated and dry that it seems ready to spontaneously burst into flames, the arrival of fresh, flowing water is nothing short of miraculous. Shimmering mirages turn to real water as I advance into the long dry lake-bed of Lake Xau, to witness the return of the Okavango floodwaters to this distal terminus for the first time in 40 years.
A huge twister lifts the fine dust from the dry part of the lake-bed (Photo: P Hancock)
A towering dust-devil sweeping across the dry plain suddenly collapses as it reaches the water’s edge. As the flood waters slowly advance, they fill small holes and burrows and flush insects and rodents and other small creatures, but as yet there are no waterbirds present to capitalize on this bounty. Only a few wily Pied Crows wade in the shallows enjoying this unexpected bounty.
A Pied Crow catches a spider flushed by the water (Photo: P Hancock)
This is quite different from the first recent flooding of Lake Ngami in 2004, where Marabou Storks, Blacksmith Lapwings and other waterbirds followed the advancing floodwaters to the lake, making an ‘instant’ birding spectacle.
However, it is expected that there will be some similarities between the rebirth of the two lakes. Currently, Lake Xau is heavily overgrazed, so there are extensive, open, shallowly inundated mudflats which will soon attract the incoming summer migrant waders. Lake Xau, like Lake Ngami, is a nutrient sink, and all the accumulated cattle dung, once dissolved, will fuel food chains for aquatic invertebrates, fish, amphibians and ultimately birds. BirdLife Botswana is committed to monitoring these changes in the hope that Lake Xau will substantially boost local and migrant bird populations.