Lake Xau comes up to expectations

Thousands of Ruffs have now discovered Lake Xau.

Lake Xau has been a dry dustbowl for the past three decades. However the exceptional 2011 floods from the Okavango coursed down the Boteti River for over 250 kilometres beyond Maun to reach Lake Xau late last year. Birds have been rather slower than expected in finding this huge, shallow waterbody, but waterbird counts conducted by BirdLife Botswana member, Chris Brewster, over the Christmas period, show that it is well on its way to achieving recognition as an Important Bird Area (IBA).

One of the criteria for an area to achieve IBA status is that it should harbour significant numbers of globally threatened birds. In this regard, the key dryland bird species such as Bateleur and Martial Eagle, and Lappet-faced and White-backed Vultures (long resident in the area) are now being joined by globally threatened waterbirds such as Wattled Crane and Black-winged Pratincole. Congregatory waterbirds have not yet built up to numbers which exceed the critical threshold (0,5% of the global or regional population) but numbers of Ruffs and Great White Pelicans are already notable.

At present, it is the number of Black-winged Pratincoles at the lake (2,000) which is of special interest. In a recent article in Africa Birds and Birding magazine, Phil Hockey (Director of the Percy Fitzpatrick Institute of African Ornithology) suggested that this species might be in serious trouble. Very few pratincoles relative to 20 years ago are now being seen (cf the sighting of 10,000 by Penry and Tarboton at Lake Ngami during the 1980s). Phil Hockey suggested that the pratincoles may have shifted their non-breeding range northwards into northern Botswana but this is unlikely to be the case given the few sightings we have. Chris Brewster's count of 2,000 at Lake Xau is the best news we have had for this species in recent years, and highlights the importance of this 'new' wetland.

Apart from the pratincoles, there is much of interest to be seen at Lake Xau - it is certainly a spot worth watching!

Waterbirds arrive at Lake Xau

The arrival of waterbirds at Lake Xau since it started filling has been less than spectacular! However, there is no doubt that the lake is Botswana 13th Important Bird Area (IBA) in the making.

The extent of flooding of the lake in 2010 (Photo: P Hancock)

By mid-November, the Boteti floodwaters, over 250 kilometres south of Maun and still moving, trickled out onto the long dry bed of Lake Xau. They extended about eight kilometres into the huge sump – the river’s natural terminus – and then spread out laterally and formed a shallow, open mudflat before stopping flowing. This waterbody has been colonized by a few dozen Red-billed Teal and Southern Pochard, and lesser numbers of Little and Cattle egrets and Grey Herons.

A Grey Heron drops in for a bit of fishing (Photo: P Hancock)

Wader numbers and diversity are still low, with a few Ruffs, Common Greenshanks, Wood Sandpipers and a single Black-winged Stilt being present. Other species seen at this time include Blacksmith Lapwing, Glossy Ibis and two Yellow-billed Storks.

The shallow mudflats are suitable for waders, including the Common Greenshank (Photo: P Hancock)

There have been quite good rains in the general area of Lake Xau, so that there is standing water on small pans and mudflats between Rakops and Mopipi, and this may have diluted the number of birds. However, the area is still worth a visit as it is likely to attract large numbers of waders still. The habitat is ideal for the incoming Palaearctic migrants and species such as Black-winged (and Collared) Pratincole and Caspian Plovers could reach good numbers. Birders visiting the area are requested to keep good records, and to send this information to Pete Hancock at birdlifemaun@gmail.com.