A. tristis is lacking, but as A. tristis are fruit and nectar feeders and are known to
damage fruit crops (Gumede and Downs 2019) it is likely that impacts do occur.
Columba livia is controversial because it exists as feral populations which interact
with captive populations used as pets and for pigeon racing. Currently there are no
systematic control programmes for this species (Measey et al. 2020, Chap. 5).
Corvus splendens and A. platyrhynchos are under ongoing control in Durban and
Cape Town, in operations funded by DEA: NRM and supported by a range of
institutions, principally local authorities. The two avian control projects are covered
in more detail below.
Rose-ringed Parakeets Psittacula krameri are established as breeding colonies in
metropolitan areas of Gauteng, Durban and Cape Town and smaller towns and cities
Steytlerville and Pietermaritzburg (Hart and Downs 2014). The Rose-ringed Parakeet is listed in Category 2 of NEM:BA, but has only been controlled on a small
scale in Somerset west, where birds were caught and removed from a single dwelling
resulting in local extirpation (L. Stafford, pers. comm.).
22.8.1 Corvus splendens (House Crow)
The Cape Town population has been under continuous management since 2009 and
has been reduced from a peak population of 10,000 in 2010 to about 300 individuals.
The eThekwini (Durban) population was at very low levels (thought to be <10
individuals), but recovered following a suspension of management due to cessation
of funding from the government in 2017. In early 2018 a new monitoring and control
programme was funded by DEA: NRM and eThekwini Municipality, and is ongoing. Other populations of C. splendens occur in Richards Bay and East London. The
Cape Town and eThekwini programmes aim to extirpate the species from these
locations. Over ZAR 8 million has been spent on the programme over 8 years of
active control using poison baits and trapping at House Crow roosting and feeding
sites.
As is common in eradication projects, the last few animals are difficult to detect
and remove, especially given the high intelligence of these birds which learn to avoid
people and baiting areas (Suliman et al. 2011). It is thought that novel approaches
will need to be employed to finally achieve extirpation in the four coastal cities that
are currently invaded and funding for continued monitoring is likely to be required in
perpetuity due to the high risk of reintroduction at these ports.
22.8.2 Anas platyrhynchos (Mallard)
Anas platyrhynchos hybridise with native Anas undulata (Yellow-Billed Ducks). It
was thought that genetic introgression and A. platyrhynchos aggressive competitive
behaviour may lead to suppression of native duck populations in urban and peri648
S. J. Davies et al.
damage fruit crops (Gumede and Downs 2019) it is likely that impacts do occur.
Columba livia is controversial because it exists as feral populations which interact
with captive populations used as pets and for pigeon racing. Currently there are no
systematic control programmes for this species (Measey et al. 2020, Chap. 5).
Corvus splendens and A. platyrhynchos are under ongoing control in Durban and
Cape Town, in operations funded by DEA: NRM and supported by a range of
institutions, principally local authorities. The two avian control projects are covered
in more detail below.
Rose-ringed Parakeets Psittacula krameri are established as breeding colonies in
metropolitan areas of Gauteng, Durban and Cape Town and smaller towns and cities
Steytlerville and Pietermaritzburg (Hart and Downs 2014). The Rose-ringed Parakeet is listed in Category 2 of NEM:BA, but has only been controlled on a small
scale in Somerset west, where birds were caught and removed from a single dwelling
resulting in local extirpation (L. Stafford, pers. comm.).
22.8.1 Corvus splendens (House Crow)
The Cape Town population has been under continuous management since 2009 and
has been reduced from a peak population of 10,000 in 2010 to about 300 individuals.
The eThekwini (Durban) population was at very low levels (thought to be <10
individuals), but recovered following a suspension of management due to cessation
of funding from the government in 2017. In early 2018 a new monitoring and control
programme was funded by DEA: NRM and eThekwini Municipality, and is ongoing. Other populations of C. splendens occur in Richards Bay and East London. The
Cape Town and eThekwini programmes aim to extirpate the species from these
locations. Over ZAR 8 million has been spent on the programme over 8 years of
active control using poison baits and trapping at House Crow roosting and feeding
sites.
As is common in eradication projects, the last few animals are difficult to detect
and remove, especially given the high intelligence of these birds which learn to avoid
people and baiting areas (Suliman et al. 2011). It is thought that novel approaches
will need to be employed to finally achieve extirpation in the four coastal cities that
are currently invaded and funding for continued monitoring is likely to be required in
perpetuity due to the high risk of reintroduction at these ports.
22.8.2 Anas platyrhynchos (Mallard)
Anas platyrhynchos hybridise with native Anas undulata (Yellow-Billed Ducks). It
was thought that genetic introgression and A. platyrhynchos aggressive competitive
behaviour may lead to suppression of native duck populations in urban and peri648
S. J. Davies et al.