to those of East Africa and Madagascar and are affiliated to Indian haplogroups,
rats in Cape Town belong to a haplogroup from current-day Myanmar, Thailand,
Cambodia and Vietnam region (Aplin et al. 2011). These two genetic groups suggest
multiple introductions to South Africa, via East Africa and direct from the Middle
East or India, and chromosomal differences suggest that they remain independent
races. House rats were reported to be abundant on Robben Island from 1614
(Crawford and Dyer 2000). The house rat has invaded considerably into
South Africa, becoming firmly established in agricultural and urban settings,
although it has also been found in forested environments, away from human
settlements (Monadjem et al. 2015). However, rats have been found to competitively
exclude native mice from homes in rural subsistence settings (Monadjem et al.
2011), such that they are the dominant rodent in and around rural homesteads
(Taylor et al. 2012; Themb’alilahlwa et al. 2017).
5.3.11.3 Rattus norvegicus (Brown Rat)
Brown Rats were likely introduced to South Africa via ship traffic between Asia and
Europe in the seventeenth century, although there are no records to indicate the
date of introduction (Skead et al. 2011). It is a strongly commensal species and its
distribution is assumed to remain coastal, associated with port and urban areas.
However, this species has also been identified in Gauteng province (Bastos et al.
2011; Mostert 2009) presumably originating from coastal areas. This extension of
their distribution may have occurred through airfreight (Picker and Griffiths 2011).
5.3.11.4 Rattus tanezumi (Asian House Rat)
Asian House Rats, Rattus tanezumi, were previously thought to be absent from
Africa, but were identified by molecular methods in 2005 (Bastos et al. 2005). This
species appears to be widespread throughout both South Africa and Swaziland
(Bastos et al. 2011), despite the fact that ecological niche modelling had suggested
the climate of South Africa to be unsuitable, based upon its current range (Monadjem
et al. 2015). The Asian house rat originates in South-East Asia, and is not considered
to have the same high impact as R. rattus and R. norvegicus, but, considering it is a
more recent invasion, its distribution should be monitored for signs of adaptation and
growing impact.
5.3.11.5 Sciurus carolinensis (Grey squirrel)
Grey Squirrels were deliberately introduced to Cape Town by CJ Rhodes around the
turn of the twentieth century (Smithers 1983). Despite more than 100 years since
their introduction, this species has not spread beyond the south-western Cape.
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rats in Cape Town belong to a haplogroup from current-day Myanmar, Thailand,
Cambodia and Vietnam region (Aplin et al. 2011). These two genetic groups suggest
multiple introductions to South Africa, via East Africa and direct from the Middle
East or India, and chromosomal differences suggest that they remain independent
races. House rats were reported to be abundant on Robben Island from 1614
(Crawford and Dyer 2000). The house rat has invaded considerably into
South Africa, becoming firmly established in agricultural and urban settings,
although it has also been found in forested environments, away from human
settlements (Monadjem et al. 2015). However, rats have been found to competitively
exclude native mice from homes in rural subsistence settings (Monadjem et al.
2011), such that they are the dominant rodent in and around rural homesteads
(Taylor et al. 2012; Themb’alilahlwa et al. 2017).
5.3.11.3 Rattus norvegicus (Brown Rat)
Brown Rats were likely introduced to South Africa via ship traffic between Asia and
Europe in the seventeenth century, although there are no records to indicate the
date of introduction (Skead et al. 2011). It is a strongly commensal species and its
distribution is assumed to remain coastal, associated with port and urban areas.
However, this species has also been identified in Gauteng province (Bastos et al.
2011; Mostert 2009) presumably originating from coastal areas. This extension of
their distribution may have occurred through airfreight (Picker and Griffiths 2011).
5.3.11.4 Rattus tanezumi (Asian House Rat)
Asian House Rats, Rattus tanezumi, were previously thought to be absent from
Africa, but were identified by molecular methods in 2005 (Bastos et al. 2005). This
species appears to be widespread throughout both South Africa and Swaziland
(Bastos et al. 2011), despite the fact that ecological niche modelling had suggested
the climate of South Africa to be unsuitable, based upon its current range (Monadjem
et al. 2015). The Asian house rat originates in South-East Asia, and is not considered
to have the same high impact as R. rattus and R. norvegicus, but, considering it is a
more recent invasion, its distribution should be monitored for signs of adaptation and
growing impact.
5.3.11.5 Sciurus carolinensis (Grey squirrel)
Grey Squirrels were deliberately introduced to Cape Town by CJ Rhodes around the
turn of the twentieth century (Smithers 1983). Despite more than 100 years since
their introduction, this species has not spread beyond the south-western Cape.
128
J. Measey et al.