WATERFOWL & WESTERN LEOPARD TOADS
Summary of literature review identifying waterfowl suited to WLT breeding sites
Introduction
This list has been compiled for the Western Leopard Toad Conservation Committee with specific reference to the breeding sites of the Western Leopard Toad (Sclerrophrys pantherina).
In an effort to maximize the breeding success of the Toads, certain management actions and or preventative measures could be important. This is especially important where humans impact directly on the breeding sites and foraging ranges of toads. One of these impacts is the management of domestic and alien ducks, and the option of using suitable indigenous species. This list therefore identifies the indigenous waterfowl species most suitable for introduction into wetlands that are important breeding areas for WLT. Waterfowl seldom threaten adult toads, and their impacts are largely to the eggs and tadpoles of the WLT in their breeding ponds. It is also important to mention that the use of locally indigenous species is recommended and therefore details on the distribution of each species has been included.
The purpose of this document is to identify species for introduction to dams and ponds. Please note that indigenous waterfowl that have become established on private property on their own accord must under no circumstance be shot, hunted, removed by whatever means or have their nests pillaged, etc. Waterfowl are highly mobile and suitable areas may be colonized and deserted by birds at any time. Birds may be present only sporadically, or only at certain times of day, or they may take up residence for breeding or moulting. Predation of tadpoles is natural and part of selection process acting on WLT. Any attempt to remove wild populations or individuals - where they are suspected of severely impacting WLT - must be done with the consent of and in collaboration and consultation with the City’s Biodiversity Management Branch and/or CapeNature.
Please note that this list is based on literature only. It is subject to revision following studies resulting from future introductions as well as interviews with existing breeders.
To this purpose, waterfowl have been divided into 3 categories:
“Toad friendly”: Species that do not feed on tadpoles, and are thus compatible with WLT breeding ponds;
“Questionable”: Species that are less suitable, but would probably only impact in WLT under unusual conditions. Supplementary feeding could prevent predation on tadpoles, but this must still be confirmed. Until more information is available these species are not recommended for introduction into WLT breeding ponds; &
“Species not suitable”, as they are known to feed on tadpoles and should never intentionally be introduced into WLT breeding sites.
Note that the Mallard and White Quackers are illegal and may not be allowed into the wild. Please report any birds seen to your conservation officer for immediate eradication.
Click on the links below to skip to a section:
Toad-friendly Options | Questionable Options | Species not suitable | Exotic species to be removed
TOAD-FRIENDLY OPTIONS:
White-backed Duck (Thalassornis leuconotus)
Distribution: Scattered in E. Cape. Uncommon and localized in W. Cape with the majority of the population confined to a few water bodies, mostly on the northern fringes of Cape Peninsula and southern coastal lowlands.
Diet: A forager in bottom muds among aquatic herbs. Some 97% of their diet consists of aquatic herbs, in particular Nymphaea & Nymphoides, as well as seeds. Chironomid larvae have been found in the stomachs of ducklings.
Southern Pochard (Netta erythrophthalma)
Distribution: Widespread but patchy, most abundant (but with large annual fluctuations) in W. Cape and on the highveld.
Diet: Little is known about their diet, but the majority of the stomach contents studied(almost 99%) consist of plant material, mainly seeds and fruit, but also Nymphaea & Nymphiodes, rhizomes, grass and leaves. Animal material never exceeds 3%, and includes fluke snails.
South African Shelduck (Tadorna cana)
Distribution: Particularly abundant in W. Cape, E. Cape and N. Cape and southern Free State.
Diet: Young feed largely on submerged aquatic vegetation, including algae. Adults mainly feed on plant material (96%) such as maize seeds, sorghum seeds and submerged aquatic plants (e.g. algae). Animal food is ingested during the pre-breeding period and includes mainly crustacean and tendipedid larvae and pupae, in addition to plant material.
Egyptian Goose (Alpochen aegyptiaca)
Distribution: Extensive range in SA. Most abundant in W. Cape, KZN interior and Mpumalanga. Absent only from regions of extreme aridity or high altitude.
Diet: Primarily a grazer and grass seed-stripper. They feed on grasses, grain, shoots, leaves, aquatic plants, young crops, wheat, oats, lucerne, barley, groundnut and sunflowers. When moulting they rely solely on aquatic algae, pondweed & Kwick Cynodon dactylon. Invertebrates are mostly ingested by accident, but they will occasionally eat termite alates.
Fulvous Duck (Dendrocygna bicolor)
Distribution: Recorded widely but sparsely in NE South Africa, but a fairly common summer visitor to Witwatersrand. Uncommon in Free-State. Mainly in coastal lowlands of KwaZulu-Natal, especially north and less frequent inland. Extends southwards through E. Cape to W. Cape, but a rare visitor with few breeding records.
Diet: Mainly plant material (98.8%) including grass seeds, filaments of algae, Nymphaea & Nymphoides. Aquatic insects form 1.2% of diet.
White-faced Duck (Dendrocygna viduata)
Distribution: Widespread and common in lowveld and bushveld. Widespread in KwaZulu-Natal. Fairly widespread in northern and central Free-State. Scattered and irregular occurrence through E. Cape and W. Cape.
Diet: Dominated by plant material (99 – 100%) with possible slight increase in small invertebrates during breeding and moult. They are exceptionally efficient at assimilating protein from plant matter. Animal material ingested includes molluscs and insects.
Comb Duck / Knob-billed Duck (Sarkidiornis melanotos)
Distribution: Widespread in lowveld and bushveld of north-east. Common in floodplains of north-east KZN. Irregular visitor or vagrant to Free State, E., W. and N. Cape.
Diet: Almost exclusively plant material which includes crop residue, seeds, fruits of grasses and herbs, rhizomes, leaves (including Nymphaea & Nymphoides) and negligible amounts of animal matter such as termite alates.
QUESTIONABLE OPTIONS:
Maccoa Duck (Oxyura maccoa)
Distribution: South African strongholds in W. Cape and Highveld. Scattered records throughout uplands of KZN, also in N. Cape, E. Cape and Free-State.
Diet: Forages almost exclusively by diving, feeding in bottom muds. Feeds mainly on small invertebrates such as midge larvae and pupae (45%), ostracods (32%), gastropods (19%) and other organisms (4%). They also feed on snails, water fleas and some seeds and roots.
Yellow-billed Duck (Anas undulata)
Distribution: Common throughout South Africa, although largely absent from arid areas.
Diet: Some 83% plant material (such as new growth of aquatic plants) and 17% animal material (mainly chironomid larvae). Females eat less plant matter (71%) than Males but the animal component remains similar with the inclusion of mayflies. Pre-fledging juveniles eat substantially less plant material (29%) and a wider range of animal species (including larvae, grasshoppers and snails).
Notes: Yellow-billed Ducks hybridize with Mallard and White Quackers. The main reason why Mallards & White Quackers must be removed is that our native Yellow-billed Duck populations are being replaced by undesirable hybrid swarms. These hybrid individuals must also be removed.
Spur-winged Goose (Plectropterus gambensis)
Distribution: Common in W. and E. Cape, but sparse in N. Cape. Has spread into the Nama Karoo. Western Cape birds are possibly derived from introductions in early 1940’s.
Diet: The bulk of the diet consists of plant material including rhizomes, stolons, leaves, seeds and filaments of algae. Some animal matter is included in the diet such as termite alates, bugs, beetles and larvae. Young also catch small fish by diving.
African Black Duck (Anas sparsa)
Distribution: Most common below escarpment in Limpopo, Mpumalanga, KwaZulu-Natal, E. Cape and W. Cape, but also widespread over much of eastern and southern central plateau. Extends into Karoo along rivers.
Diet: Little is known, but it is presumed to feed mainly on benthic invertebrates and vegetable matter such as seeds and fruit. Animal material eaten includes insect larvae, crustaceans, molluscs, crabs and fish fry.
African Pygmy-Goose (Nettapus auritus)
Distribution: Widespread in KwaZulu-Natal, but with more scattered southwards along coastal plain, with some records further inland including Kruger NP. Few records, mostly pre-1920, from E. Cape.
Diet: Reported as essentially surface feeders, but mostly dives to obtain Nymphaea pods. Some 98 – 100% of the diet consists of ripe seeds and flower parts of water lilies. Other food includes grasses, pondweeds, seeds, fish fry, insects and moth larvae and pupae.
SPECIES NOT SUITABLE:
Red-billed Teal (Anas erythrorhyncha)
Distribution: Recorded over most of South Africa, but most common on the Highveld and in W. Cape, less uniformly distributed elsewhere and only scattered over much of N. Cape.
Diet: Consists of plant (24%) and animal material (76%), but proportions vary. They will feed on maize, wheat and sunflower seeds, lucerne, grass seeds as well as worms, aquatic crustaceans, tadpoles and fish.
Cape Shoveller (Anas smithii)
Distribution: Most abundant in lowlands of W. Cape, and Highveld of Free-State, Mpumalanga, Gauteng and NW Province. Scattered from west coast through to Nama Karoo, E. Cape and KwaZulu-Natal. Patchy or absent elsewhere.
Diet: Some 70% animal matter such as snails, insects, crustaceans and tadpoles and 30% plant material such as leaves and stems.
Hottentot Teal (Anas hottentota)
Distribution: Most common in northern Highveld of NW Province, Gauteng and Mpumalanga, extending to uplands and coastal lowlands of KwaZulu-Natal. Scattered elsewhere in South Africa, Free-State N. Cape and E. Cape. A rare visitor to W. Cape.
Diet: Some 35 – 55% of the diet is animal material, which specifically includes small frogs. During Jun – Nov the percentage animal material ingested increases to over 90%.
Cape Teal (Anas capensis)
Distribution: Widespread in southern Africa. Most common in western coastal lowlands of W. Cape and on western Highveld of inland plateau.
Diet: Forages mostly by filtering on surface and below, but will also pick animals off submerged vegetation. The diet consists of 80 - 99% animal material which includes insects, larvae, crustaceans and platanna tadpoles. The 17% plant material in their diet consists mainly of water plants (stems & leaves).
EXOTIC SPECIES TO BE REMOVED:
Mallard (Anas platyrhynchos)
Distribution: There are two main localized, feral populations: in W. Cape and Gauteng. These probably originating from escapees from wildfowl collections.
Diet: Omnivorous, but food varies with season and locality. Eats seeds, cereals, aquatic vegetation and roots, also insects, molluscs, crustaceans, annelids, amphibians and fish.
Note: The White Quacker is a Mallard and also breeds with Yellow-billed Ducks. Mallards and White Quackers must be reported and eliminated wherever they are found in the wild. Permits are required to keep Mallards or White Quackers, and they must be in enclosures.
Compiled by: Suretha Dorse, February 2009.
Source: Hockey, PAR, Dean WRJ, Ryan PG (eds), 2005, Roberts – Birds of Southern Africa, VIIth ed. The Trustees of the John Voelcker Bird Book Fund, Cape Town.
Acknowledgements: We thank the following for comments on this list: Clifford Dorse, Dr. Tony Rebelo & Dr. John Measey.
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