5.1 Introduction
The emphasis on biological invasions in South Africa (as elsewhere in the world) has
historically been on plants, because of their visibility, their perceived higher impact
and the large areas they have invaded in different biomes of the country (Pyšek et al.
2008; Richardson and van Wilgen 2004). Animal invasions have received notably
less attention, and only following the passing of South Africa’s National Environmental Management: Biodiversity Act (Act No. 10 of 2004) (hereafter NEM:BA)
were legal and financial measures put in place to control or remove them. Vertebrate
invasions in freshwater environments (i.e. all fishes) are covered elsewhere in
this book (Weyl et al. 2020; Chap. 6). In this chapter we provide information on
30 invasions by vertebrate species (mammals, birds, reptiles and amphibians,
Table 5.1).
Many of South Africa’s invasive vertebrates have undergone rapid range expansions, or been transported within the region, beyond their historical ranges. These are
often referred to as extralimital (e.g. Spear and Chown 2009a), or even as domestic
exotics (Guo and Ricklefs 2010), and therefore many have not been historically
included in lists of invasive species, as they are not alien to the geopolitical unit of
South Africa. Our selection of species included here was initially based on terrestrial
vertebrate invasions listed in Picker and Griffiths (2017), but we have augmented
this to include other vertebrate species that fit the definition of “alien” by Richardson
et al. (2011a). We acknowledge that there are many alien vertebrates present in
captivity (stages B1, B2, B3 in Blackburn et al. 2011), and that there are also
individuals that have been released from captivity both intentionally and accidentally, or transported out of their natural range (stages C1, C2). These species may
become important emerging invaders, and we refer to them explicitly in passing. In
this chapter species accounts are provided for those that have formed self-sustaining
populations, including all stages up to full invasions (stages C3, D1, D2, E).
5.2 History of Introductions, Pathways and Vectors
Prior to the arrival of European ships, South Africa was inhabited by peoples already
using domestic animals, such as Sheep, Ovis aries, Cattle, Bos taurus, Goats, Capra
hircus and Dogs Canis familiaris that were all alien to the region (see Faulkner et al.
2020, Sect. 12.2.2.1). Ships sailing around the coast at this time likely brought with
them early invaders, such as rats and mice. Although records are missing for this
period, credence to this scenario comes from the knowledge that rats (and presumably mice, although the two were both referred to as rats historically) were present in
large numbers prior to the arrival of European settlers (Crawford and Dyer 2000),
and genetic studies on rats suggest movements from the Indian subcontinent were
concurrent with those to East Africa (Aplin et al. 2011).
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The emphasis on biological invasions in South Africa (as elsewhere in the world) has
historically been on plants, because of their visibility, their perceived higher impact
and the large areas they have invaded in different biomes of the country (Pyšek et al.
2008; Richardson and van Wilgen 2004). Animal invasions have received notably
less attention, and only following the passing of South Africa’s National Environmental Management: Biodiversity Act (Act No. 10 of 2004) (hereafter NEM:BA)
were legal and financial measures put in place to control or remove them. Vertebrate
invasions in freshwater environments (i.e. all fishes) are covered elsewhere in
this book (Weyl et al. 2020; Chap. 6). In this chapter we provide information on
30 invasions by vertebrate species (mammals, birds, reptiles and amphibians,
Table 5.1).
Many of South Africa’s invasive vertebrates have undergone rapid range expansions, or been transported within the region, beyond their historical ranges. These are
often referred to as extralimital (e.g. Spear and Chown 2009a), or even as domestic
exotics (Guo and Ricklefs 2010), and therefore many have not been historically
included in lists of invasive species, as they are not alien to the geopolitical unit of
South Africa. Our selection of species included here was initially based on terrestrial
vertebrate invasions listed in Picker and Griffiths (2017), but we have augmented
this to include other vertebrate species that fit the definition of “alien” by Richardson
et al. (2011a). We acknowledge that there are many alien vertebrates present in
captivity (stages B1, B2, B3 in Blackburn et al. 2011), and that there are also
individuals that have been released from captivity both intentionally and accidentally, or transported out of their natural range (stages C1, C2). These species may
become important emerging invaders, and we refer to them explicitly in passing. In
this chapter species accounts are provided for those that have formed self-sustaining
populations, including all stages up to full invasions (stages C3, D1, D2, E).
5.2 History of Introductions, Pathways and Vectors
Prior to the arrival of European ships, South Africa was inhabited by peoples already
using domestic animals, such as Sheep, Ovis aries, Cattle, Bos taurus, Goats, Capra
hircus and Dogs Canis familiaris that were all alien to the region (see Faulkner et al.
2020, Sect. 12.2.2.1). Ships sailing around the coast at this time likely brought with
them early invaders, such as rats and mice. Although records are missing for this
period, credence to this scenario comes from the knowledge that rats (and presumably mice, although the two were both referred to as rats historically) were present in
large numbers prior to the arrival of European settlers (Crawford and Dyer 2000),
and genetic studies on rats suggest movements from the Indian subcontinent were
concurrent with those to East Africa (Aplin et al. 2011).
116
J. Measey et al.