22.6.2 Xenopus laevis (African Clawed Frog)
Xenopus laevis is widespread throughout southern Africa (Furman et al. 2015), and in
the Western Cape it is sympatric with X. gilli, the endemic, range restricted Cape
Platanna (Endangered—IUCN 2017). However, the original range of X. laevis remains
unclear (Measey et al. 2017). Furthermore, research strongly suggests that the presence
of X. laevis in the same water bodies reduces recruitment of X. gilli through competition
and predation (De Villiers et al. 2016; Vogt et al. 2017; Thorp et al. 2019). Early
research suggested that introgression was a threat to X. gilli (Picker et al. 1996), and this
formed the basis of NEM:BA listing hybrids of X. gilli and X. laevis for removal.
However, more recent genetic studies suggest that while F1 hybrids form between the
species, there is no introgression (Furman et al. 2017).
From 1985 to 2000, several thousand X. laevis were removed from the Cape of
Good Hope section of Table Mountain National Park (TMNP) with the aim of
protecting the population of X. gilli from genetic introgression in the National Park
(Picker and De Villiers 1989; De Villiers 2004). After a hiatus of 10 years in
X. laevis population control and as part of a research project conducted in collaboration with SANParks protected area management staff between 2010 and 2014, a
total of 2126 X. laevis were removed from the Cape of Good Hope section of TMNP
(Measey et al. 2014; De Villiers et al. 2016; Measey et al. 2017). Annual operations
are still underway to date (March 2019) in a collaboration between the Organisation
for Tropical Studies, SANParks and the C·I·B. Extirpation is not considered possible
as X. laevis regularly enter the park via streams from dams on adjacent private land.
22.7 Reptiles
No introduced reptile species are currently being controlled in South Africa.
22.8 Birds
Five invasive bird species have been considered for control or eradication in
South Africa to date: Acridotheres tristis (Common Myna), Columba livia (Common Pigeon), Corvus splendens (House Crow), Anas platyrhynchos (Mallard) and
Psittacula krameri (Rose-ringed Parakeet). Common Mynas are ubiquitous in many
cities and towns around South Africa (see Measey et al. 2020, Chap. 5; Potgieter
et al. 2020, Chap. 11), but no large-scale or systematic control has been attempted.
However, in parts of KwaZulu-Natal province, A. tristis trapping trials have been
conducted with the result that birds have been removed from local areas. Evidence
for strong negative impacts on avian and other species (Hart and Downs 2015) by
22 Alien and Invasive Animal Control Projects
647
Xenopus laevis is widespread throughout southern Africa (Furman et al. 2015), and in
the Western Cape it is sympatric with X. gilli, the endemic, range restricted Cape
Platanna (Endangered—IUCN 2017). However, the original range of X. laevis remains
unclear (Measey et al. 2017). Furthermore, research strongly suggests that the presence
of X. laevis in the same water bodies reduces recruitment of X. gilli through competition
and predation (De Villiers et al. 2016; Vogt et al. 2017; Thorp et al. 2019). Early
research suggested that introgression was a threat to X. gilli (Picker et al. 1996), and this
formed the basis of NEM:BA listing hybrids of X. gilli and X. laevis for removal.
However, more recent genetic studies suggest that while F1 hybrids form between the
species, there is no introgression (Furman et al. 2017).
From 1985 to 2000, several thousand X. laevis were removed from the Cape of
Good Hope section of Table Mountain National Park (TMNP) with the aim of
protecting the population of X. gilli from genetic introgression in the National Park
(Picker and De Villiers 1989; De Villiers 2004). After a hiatus of 10 years in
X. laevis population control and as part of a research project conducted in collaboration with SANParks protected area management staff between 2010 and 2014, a
total of 2126 X. laevis were removed from the Cape of Good Hope section of TMNP
(Measey et al. 2014; De Villiers et al. 2016; Measey et al. 2017). Annual operations
are still underway to date (March 2019) in a collaboration between the Organisation
for Tropical Studies, SANParks and the C·I·B. Extirpation is not considered possible
as X. laevis regularly enter the park via streams from dams on adjacent private land.
22.7 Reptiles
No introduced reptile species are currently being controlled in South Africa.
22.8 Birds
Five invasive bird species have been considered for control or eradication in
South Africa to date: Acridotheres tristis (Common Myna), Columba livia (Common Pigeon), Corvus splendens (House Crow), Anas platyrhynchos (Mallard) and
Psittacula krameri (Rose-ringed Parakeet). Common Mynas are ubiquitous in many
cities and towns around South Africa (see Measey et al. 2020, Chap. 5; Potgieter
et al. 2020, Chap. 11), but no large-scale or systematic control has been attempted.
However, in parts of KwaZulu-Natal province, A. tristis trapping trials have been
conducted with the result that birds have been removed from local areas. Evidence
for strong negative impacts on avian and other species (Hart and Downs 2015) by
22 Alien and Invasive Animal Control Projects
647