Territories and movements of African black ducks

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Territorial Black Duck (Anas sparsa) pairs maintain remarkably tight control over their section of river. About 90% of the territory is effectively defended against use by neighbouring pairs, although nonterritorial birds can sometimes hide and temporarily escape detection. Hens with broods trespass overtly although most brood rearing occurs on the parental territory. Spatial ties between mates are exceedingly close and pair bonds in territorial birds may last two or more years. Dams adjacent to the river are used only infrequently by pairs holding territories on the river. Few pairs set up territories on dams, though nonterritorial birds often used dams. Non-territorial birds do not breed, and they make up a sizeable portion of the total Black Duck population. Nonterritorial birds exist in both dense and sparse populations. Characteristics of rivers which may have favoured the evolution of the spacing and pairing system seen in Black Ducks include short- and long-term stability, and the contiguous, open nature of the habitat which makes detection of trespass relatively efficient. Territorial Black Duck pairs in the Eerste River Valley are about twice as dense (territories are about half as large) as the densest population found elsewhere. This may be due to pressure from conspecifics, to abundant resources (particularly food) for the territorial birds, or to a combination of the two.

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Reference Code: A78BAL01IDUS

Full Citation: Ball, I. P., P. G. H. Frost, W. R. Siegfried, and F. McKinney. 1978. Territories and movements of African black ducks. Wildfowl 29(1978): 61-79.

Location: ANIMAL EF: HISTRIONICUS HISTRIONICUS