The Marabou stork is an ugly bird and because of this, people tend to think it must be stupid too! But ongoing research is showing that these remarkable birds are quite capable of navigating their way across Africa, visiting sites that offer productive feeding opportunities at certain times of the year.
The Marabou stork, Leptoptilos crumeniferus, is a vulnerable species in southern Africa due to the very few breeding sites. There is a single colony (of about 30 breeding pairs) in Swaziland, while Botswana has the largest breeding population in southern Africa, of a mere 100 pairs, in the Okavango Delta. The species does not breed in South Africa or Lesotho, and there are a few minor sites in Namibia and Zimbabwe.
Against this background, how does one explain the fact that in Botswana, the Marabou stork often occurs in congregations of 3,000 to 5,000 birds? Could the relatively few breeding birds be maintaining a population of tens of thousands of storks? Or is it more likely that birds are coming to Botswana from elsewhere? Simple arithmetic, based on a clutch of two to three eggs per pair per annum shows that it would take a long, long time to produce this number of birds; it seems more probable that there is a regular influx of storks from further afield.
To find out what is happening, a project is being undertaken whereby some storks are marked with numbered wing tags. However, this will not yield any useful information unless ornithologists, birdwatchers and informed members of the public elsewhere in Africa know about the project.
This article is an appeal to all interested parties to use their networks to spread the word that people should look out for tagged birds - they are actually quite obvious - and should report their sightings to Prof AraMonadjem or Pete Hancock with the following information: date, locality (preferably with GPS co-ordinates), and tag number and colour. A digital photo would be very useful as the numbers can often be clearly seen on the image.
Information on the movements of Marabou storks has important implications for their conservation. It is speculated that the central African population in Uganda and Kenya (where the species has its stronghold) may well be providing most of the storks in southern Africa.
One of the storks tagged in Swaziland was recently seen and photographed at the Victoria Falls Crocodile Farm – a site apparently well-known to avian scavengers from all over southern Africa for the free lunches on offer!
This study is a collaboration between the All Out Africa Research Unit of the University of Swaziland, BirdLife Botswana, Denver Zoological Foundation, Kalahari Research and Conservation and KANABO Conservation Link.
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Zambezi Traveller (Issue 14, Sept 2013)