The NEMBA Alien and Invasive Species Lists name 8 species of crayfish as potentially invasive in South Africa. The various species hail from North America, Australia and Europe and many are popular in aquaculture. Escapees which form invasive populations can compete against indigenous freshwater species and alter the natural functioning of streams, rivers and dams, potentially displacing or causing the extinction of local species.
Rose-ringed parakeets are highly sought after and valued aviary birds. Unfortunately, escapees have naturalised in parts of Gauteng and KwaZulu-Natal. They can form large flocks which are destructive to agricultural plants such as maize and sunflower. They feed on and damage commercial fruits and nuts. Parakeets nest in tree holes and cavities and therefore compete against indigenous birds which use the same nesting cavities.
These parakeets are listed under NEMBA Category 2, meaning that a permit is required to keep and breed them in South Africa. For further information and advice regarding permits and keeping rose-ringed parakeets, contact the Parrot Breeder’s Association (PASA) at the following emails: firstname.lastname@example.org or email@example.com
Durban / eThekwini is a subtropical port city and is a hotspot for alien animal and plant invasions. Rose-ringed parakeets are prolific across many suburbs and red-eared slider terrapins are frequently discovered lurking in dams, parklands and waterways…discarded as unwanted pets. They feature in the top 100 list of impactful alien invasive species and pose a threat to our indigenous terrapins and endemic wildlife.
The mallard duck (Anas platyrhynchos) is a common sight around city dams and parks. People are inclined to feed these ducks which encourages their population to expand. Mallards compete against indigenous waterfowl for resources and nesting sites. They also frequently hybridise with the indigenous yellow-billed and black ducks. This reduces the genetic integrity of these indigenous birds thereby hampering conservation efforts.
House crows (Corvus splendens) are problematic invasive birds as they associate strongly with informal settlements and industrial areas. They are bold and intelligent and can become aggressive towards children, stealing their food. They also quickly snatch food from street traders. Because they live near people, their droppings may fall onto food items when perched above tuckshops and vendor stands, thereby transmitting enteric diseases to people.
House crows are under management by the City of Cape Town and the population is extremely low due to active intervention. However, there is always a risk of new arrivals coming in by passing ships.
House crows (Corvus splendens) are problematic invasive birds as they associate strongly with informal settlements and industrial areas. They are bold and intelligent and can become aggressive towards children, stealing their food. There are two hotspots for these birds in KwaZulu-Natal – around Durban / eThekwini and around Esikhawini on the outskirts of Richard’s Bay. Authorities have been removing nests, but nests are difficult to access as they are often built high up in trees.
You can report sightings of house crows on the platform: www.inaturalist.org
The Himalayan tahr established on Table Mountain from some zoo escapees in the 1930s. Their population increased exponentially and research into their diet and environmental impacts were undertaken. It was found that an increased population would impact negatively on vegetation and biodiversity in Table Mountain National Park, including soil and rock erosion. They were also competing against indigenous klipspringer. A culling operation was initiated and today there are only a handful of tahr left which are under active management.
Harlequin lady beetle
The harlequin lady beetle is a predatory beetle which outcompetes indigenous ladybeetles and other insects and is known to taint agricultural crops, including grapes. This orange to red beetle has scattered black spots on its wings and a black W or M shape on a white pronotum (neck area). This beetle is found in Asia and was first detected in South Africa around 2001. They have now spread across most parts of South Africa.
European shore crab
The European shore crab is also known as the green crab. It has become a nuisance animal in ports and docks around Cape Town. They are found in Table Bay and Hout Bay.
The Bongo is an attractive antelope related to the kudu and bushbuck genus. There are two recognised subspecies – the Western or lowland bongo (Tragelaphus euryceros euryceros) which occurs widely across lowland forest of West and Central Africa, and the Eastern or mountain bongo (Tragelaphus euryceros isaaci) confined to mountains of central Kenya. This antelope is listed as a Category 1a species under the NEMBA Alien and Invasive Species Regulations.