Red-knobbed Coot

FORAGING & FOOD: Forages either by standing in shallow water, or swimming, picking items from water surface, or by diving⁴⁰. Also walks on shores of water bodies, grazing short grasses³⁶ or green cultivated crops⁴⁰. Commonly grazes on short grass lawns around water features in parks and gardens⁶. Eats mainly plant material, incl filamentous algae (Chlorophyceae), macroscopic alga Chara globularis, aquatic ferns (Marsilia spp), stems, flowers, fruits and aerial roots of knuckle-beans Aeschynomene fluitans, stems, leaves and fruits of Knotweed Persicaria limbata, stems and leaves of Saw-weed Najas pectinata, Ditch Grass Ruppia maritima, Water Hyacinth Eichhornia crassipes and Torpedo Grass Panicum repens³⁶, and stems, leaves and fruits of Fennel-leaved Pondweed Potamogeton pectinatus (principal food at Barberspan, NW Province⁹ and at Swartvlei, Wilderness, W Cape¹¹). At Bot R, W Cape, thought to graze on Cape Eelgrass Zostera capensis¹³. In E Cape, eats leaves of Couch Paspalum Paspalum distichum²⁶. Also eats bivalve molluscs Musculus virgiliae¹¹, other molluscs (incl Gastropoda), crustaceans, insects, campers' scraps and occasionally carrion³⁶, and noted eating cow-dung³¹. Opportunistic, frequently feeding in wake of diving White-backed Ducks⁴. 1 group of 45 birds moved at least 5 km from nearest suitable habitat to feed on Estuarine Mud prawns Upogebia africana flushed from their holes by flooding at Kasouga R mouth, E Cape²⁶. At Bot R, metabolised energy est 691 kJ/d for wild birds and 516 kJ/d for captive birds, with mean mass 720 g³⁰. Daily macrophyte consumption est 82.4 g dry mass/bird, and annual consumption by Bot R population est 759.5 t dry mass, equal to 9.9-12.5% of annual macrophyte production in estuary³⁰. At Swartvlei, Wilderness, W Cape, annual consumption of Fennel-leaved Pondweed (av daily population size 1 851±1 226) est 48.2 t dry matter, equal to 3.01% of total pondweed production¹¹.

Author:WRJ Dean