numerous reports of encounters with escaped or released pet reptiles. To date, pet
reptiles are not known to have become established in the country, but there has been
an exponential increase in imports from an increasing number of originating countries (van Wilgen et al. 2010). However, nearly 300 species of alien herpetofauna are
known to have been imported into South Africa and are in captivity (van Wilgen
et al. 2008). South Africans have a preference for pet reptiles that are large, easy to
breed and colourful (van Wilgen et al. 2010).
Like reptiles, amphibian invasions in South Africa are currently minimal, but
there is concern that increases in trade may bring about new invasions (Measey et al.
2017; van Wilgen et al. 2008; Measey et al. 2019; Mohanty and Measey 2019).
Incidents of jump dispersal as contaminants of horticulture, with wood and even
adhered to vehicles are apparently common, likely underreported, and include
international as well as local movements (Measey et al. 2017). Suggestions have
been made that certain taxonomic groups of southern African amphibians are
predisposed to being moved large distances, such that they pose a threat to countries
outside the region. Of particular note in this respect are the ongoing invasions of
Sclerophrys gutturalis (Guttural Toad) and Hyperolius marmoratus (Painted Reed
Frog). A common feature of South African invasive amphibians is the use of novel
permanent man-made water bodies, in the form of farm impoundments or garden
ponds, as a resource that facilitates reproduction and dispersal through steppingstone movement across the landscape (Davies et al. 2013; Measey et al. 2017).
Xenopus laevis (the African Clawed Frog) is endemic to South Africa, but
invasive on four other continents (Measey et al. 2012). Genetic investigations of
many of the invasions show the source population to be the extreme south-east of the
country (e.g. De Busschere et al. 2016; Wang et al. 2019), following the evangelical
breeding and distribution of species by nature conservation authorities (see van
Wilgen 2020, Sect. 2.1, and Weyl et al. Chap. 6). African clawed frogs were
exported for pregnancy testing of people, and later for scientific investigations, but
most recently as pets (Gurdon and Hopwood 2003; van Sittert and Measey 2016),
but most animals imported into the USA were bred in China, with no ongoing trade
from South Africa (Measey 2017). In South Africa, the African clawed frog has
undoubtedly extended its range by utilising artificial impoundments, as well as being
seeded by fishermen for later use as bait (Measey et al. 2017).
5.3 Mammalia
5.3.1 Sus scrofa (Domestic Pig)
Domestic Pigs were originally introduced to South Africa by Neolithc farmers
around 9000 years ago (Picker and Griffiths 2011). Since this time, S. scrofa is
likely to have formed part of the manifest of many shipping vessels, and additional
stocks arrived to populate farms. Deliberate attempts to establish self-sustaining feral
populations were also made by the Department of Forestry as a form of biological
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reptiles are not known to have become established in the country, but there has been
an exponential increase in imports from an increasing number of originating countries (van Wilgen et al. 2010). However, nearly 300 species of alien herpetofauna are
known to have been imported into South Africa and are in captivity (van Wilgen
et al. 2008). South Africans have a preference for pet reptiles that are large, easy to
breed and colourful (van Wilgen et al. 2010).
Like reptiles, amphibian invasions in South Africa are currently minimal, but
there is concern that increases in trade may bring about new invasions (Measey et al.
2017; van Wilgen et al. 2008; Measey et al. 2019; Mohanty and Measey 2019).
Incidents of jump dispersal as contaminants of horticulture, with wood and even
adhered to vehicles are apparently common, likely underreported, and include
international as well as local movements (Measey et al. 2017). Suggestions have
been made that certain taxonomic groups of southern African amphibians are
predisposed to being moved large distances, such that they pose a threat to countries
outside the region. Of particular note in this respect are the ongoing invasions of
Sclerophrys gutturalis (Guttural Toad) and Hyperolius marmoratus (Painted Reed
Frog). A common feature of South African invasive amphibians is the use of novel
permanent man-made water bodies, in the form of farm impoundments or garden
ponds, as a resource that facilitates reproduction and dispersal through steppingstone movement across the landscape (Davies et al. 2013; Measey et al. 2017).
Xenopus laevis (the African Clawed Frog) is endemic to South Africa, but
invasive on four other continents (Measey et al. 2012). Genetic investigations of
many of the invasions show the source population to be the extreme south-east of the
country (e.g. De Busschere et al. 2016; Wang et al. 2019), following the evangelical
breeding and distribution of species by nature conservation authorities (see van
Wilgen 2020, Sect. 2.1, and Weyl et al. Chap. 6). African clawed frogs were
exported for pregnancy testing of people, and later for scientific investigations, but
most recently as pets (Gurdon and Hopwood 2003; van Sittert and Measey 2016),
but most animals imported into the USA were bred in China, with no ongoing trade
from South Africa (Measey 2017). In South Africa, the African clawed frog has
undoubtedly extended its range by utilising artificial impoundments, as well as being
seeded by fishermen for later use as bait (Measey et al. 2017).
5.3 Mammalia
5.3.1 Sus scrofa (Domestic Pig)
Domestic Pigs were originally introduced to South Africa by Neolithc farmers
around 9000 years ago (Picker and Griffiths 2011). Since this time, S. scrofa is
likely to have formed part of the manifest of many shipping vessels, and additional
stocks arrived to populate farms. Deliberate attempts to establish self-sustaining feral
populations were also made by the Department of Forestry as a form of biological
120
J. Measey et al.