The Ecology and Numbers of Aquatic Birds on the Kafue Flats, Zambia R

The Ecology and Numbers of Aquatic Birds on the Kafue Flats, Zambia R

Victorian coast. The Department of National Parks Authority and to the Zoology at Monash University already is Director of Lighthouses, Commonwealth beginning to work in co-operation in a Department of Shipping and Transport, number of ways with the Fisheries and for permission to make plans for such Wildlife Department, and it is envisaged research work in areas under their jurisdic­ that further co-operation will arise in the tion. case of the Cape Barren Goose. Thus, for Research is the basis of any conservation example, research workers making obser­ programme. The research discussed above, vations regularly on the islands could assist together with the protection measures, with poilcing, while their transport diffi­ would constitute such a programme. Since culties might be eased by the Department the Cape Barren Goose, like most water­ vessel. Again, while research workers catch fowl, is a potential game bird, a conserva­ geese for banding and other purposes, X-ray tion programme for it is the same as a game examination of the birds (for determination management programme. Eventually, any of shooting pressure, as already in progress successful game or wildlife management for ducks) could be carried out. Also, at the programme comes to include some con­ Department’s wildfowl study area at Lara trolled cropping. This would no doubt be a breeding programme for geese is planned ; appreciated by sporting interests in the studies complementary to those in the State. In addition, a successful programme islands could be made, and birds reared for would earn world-wide respect in the field release in the islands. of conservation research, a field in which Other ecological studies for the islands present successes are few and when they are in the planning stage: a new Monash occur highly acclaimed and remarkably University Research Scholar will, it is popular (as, for example, the Koala in hoped, undertake work on the ecological Victoria and the return of the Osprey to inter-relations of burrowing sea-birds the Scottish Highlands). The World Wild­ (petrels, penguins) and rabbits. Rabbit and life Fund and the International Union for Citadel Islands are particularly suitable for the Conservation of Nature would un­ this purpose. A study of the regeneration doubtedly lend approval and support to and rehabilitation of seabirds following this project, although their commitments removal of rabbits (a project already dis­ elsewhere are already too great to make cussed with the Vermin and Noxious financial support probable. The State of Weeds Destruction Board) is proposed; Victoria has the reputation of being a the relevance of this to geese is that restora­ leader in Australian conservation matters. tion of the habitat would almost certainly It seems highly desirable that the chance result in re-occupation of these islands by to preserve one of the country’s rarest birds geese. Approach has been made to the should be seized while it yet remains. The ecology and numbers of aquatic birds on the Kafue Flats, Zambia R. J. DOWSETT and A . de VOS Department of Game and Fisheries, Chilanga, Zambia, (R. J. Dowsett) and Kafue Basin Survey, F.A.O. (A. de Vos) Introduction between a few inches and 10 feet. The rise The Kafue Flats in southern Zambia are and fall of the flood water is a gradual located at about i5°3o'S and between 27 process. and 28°E. They are flooded annually by The Kafue Flats area, with its striking the Kafue River, and extend for some 140 concentrations of Lechwe antelope and miles along the river with a width of birds (including wildfowl, shorebirds, between 10 and 30 miles. The total area wading and some fish-eating birds), has of the Flats is some 2,500 square miles. long been considered one of the greatest The area is at an elevation of about 3,100 spectacles in Africa. Many distinguished ft; it has an average rainfall of 32 inches ornithologists have expressed the opinion per annum and a mean annual temperature that the variety and numbers of aquatic of 70-75°F. The flood water rises, after birds on the Flats compare favourably with the rains have begun, in November and the best wetland areas in the world. The December and the flood peak occurs preservation of this area for all time has between April and June. At times of peak long been advocated. Two of the most flood the level of water on the Flats varies important sectors of the Flats remain CAPE BARREN GOOSE 67 under private ownership. Although con­ means of numerous observations on the siderable protection has been afforded by ground, a number of sample transects and the owners of Lochinvar Ranch (on the an aerial flight. The numbers obtained are south side of the Kafue River) and of Blue necessarily approximate due to limited Lagoon Ranch (on the north side) - pri­ time available, but these figures provide a marily to conserve Lechwe - anything basis for future research. short of the creation of a National Park Numerous observations were made dur­ must be considered unsatisfactory if this ing the period August to November on unique spectacle is to survive. Lochinvar and Blue Lagoon Ranches, Little is known about the ecology and mainly by the senior author. A good deal movements of aquatic birds in Central of ground was covered. Sixty-three days Africa. The Kafue Flats provide perfect were spent in the field in 1964 and about conditions for the study of wildfowl one quarter of this time was spent on breeding, habitat and movements. Scien­ ornithological work (the remainder being tific names of all species mentioned in the devoted to Lechwe studies). The approxi­ text will be found in Appendix 2. The mate area in which aquatic birds were nomenclature used is that of C. W. Benson censused was 50 square miles on Lochinvar, and C. M. N. White Check List of the Birds and 8 square miles on Blue Lagoon. Within of Northern Rhodesia, Lusaka, 1957. these areas most aquatic birds were con­ centrated in a few places where the habitat Numbers was suitable. Each of the concentrations Between August and November 1964 the was counted at least once. The figures in authors made preliminary attempts to Table I, which are totals of birds counted obtain an estimate of the numbers of in the concentrations, may be taken as the aquatic birds (i.e. cormorants, pelicans, totals for the whole census area of 58 herons, egrets, storks, ibises, ducks and square miles. geese) on the Flats. This was done by Table I. Numbers of aquatic birds found in censuses of 58 sq. miles within the Kafue Flats, August-November, 1964 counts av. no. per range mean sq. mile Reed Cormorant 301-348 325 5 6 Darter 74-106 90 1-6 White Pelican 1719-1999 1859 321 Grey Heron 32-46 39 0-7 Goliath Heron 32-37 35 06 Purple Heron 32-38 35 0-6 Great White Heron 124-141 133 2'3 Little Egret 42-55 49 0-8 Yellow-billed Egret 102-260 181 3 1 Cattle Egret 73-129 101 1-7 Squacco Heron 129-164 147 2'5 Rufous-bellied Heron 32-39 36 06 Openbill 1019-1247 1133 195 Saddlebill 26-28 27 0 5 Marabou 41-57 49 0-8 Wood Ibis 104-116 n o 1-9 Sacred Ibis 107-129 118 2-0 Glossy Ibis I 19-229 174 3-0 African Spoonbill 25-33 29 0-5 Hottentot Teal 52-72 62 I I Red-billed Teal 3114-5660 4387 756 White-faced Tree Duck 2227-3031 2630 45 3 Fulvous Tree Duck 1227-6327 3777 651 Knob-billed Goose 539-668 604 10-4 Spur-winged Goose 3770-4362 4066 70-1 Fish Eagle 30-36 33 0-6 African Jacana 261-597 429 7'4 Crowned Crane 106-196 151 2-6 Wattled Crane 260-264 262 4-5 Blacksmith Plover 262-574 423 7'3 Long-toed Plover 125-143 134 2'3 Stilt 97-130 114 20 Grey-headed Gull 437-1062 750 12-9 68 THE WILDFOWL TRUST Several of the species listed are known to density per square mile of 75.6 given for wander quite extensively on the Flats, but the most numerous local duck, the Red­ it has been assumed that movements on and billed Teal, would give a total o f 189,000 off the two ranches are likely to be equal. individuals in the 2,500 square miles of the It is necessary to point out that some Flats. species appeared more prone to wandering A number of sample transects were than others, and this explains the fluctua­ taken. Water levels dropped so rapidly tions in numbers of such species as Red­ during this period that in most areas billed Teal, Fulvous Tree Duck and Grey­ aquatic birds frequently had to move from headed Gull. Some species might have one suitable locality to another. These escaped notice on occasions, especially transects therefore scarcely reflect a true skulking Squacco Heron, African Jacana pattern of movements. Nevertheless, it and nesting Blacksmith Plover. Counts of seems worthwhile discussing a few general the more conspicuous species, such as aspects that arise from the data. Between Goliath Heron, Saddlebill, Spur-winged August and November 1964 there were far Goose, Fish Eagle and Wattled Crane more aquatic birds per acre of suitable show reasonable agreement between the habitat on Lochinvar than on Blue Lagoon. several counts made, and hence their range This is especially true for ducks, and less as shown in the table is limited. Fluctua­ so for egrets, herons and Spur-winged tions in some other species cannot be Geese.

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