The increase in the abundance of Pied Crows in the Western Cape and the potential threat they may represent to other indigenous bird species and biodversity in general has been raised at Forum level. Certain websites have been coming to the fore in recent months advertising services to kill Pied Crows and other perceived "problem" predators and there is a concern that some farmers may be using poison.
BirdLife South Africa is not in in favour of this approach and does not support the uncontrolled killing of Pied Crows or other indigenous wildlife. It holds to the principle that sound scientifc research is needed to determine the level of threat before control programmes can be considered. The Pied Crow issue will be taken forward as a student project at the Fitz.
Below is BLSA's position statement on Pied Crows.
Position statement on the potential impact of an increased abundance of Pied Crows Corvus albus on South African biodiversity
BirdLife South Africa (BLSA) recognises the potential threat of an increasing abundance of Pied Crows Corvus albus on other indigenous bird species as well as reptiles, amphibians and mammals.
In acknowledging this threat to biodiversity BirdLife South Africa supports the need for urgent scientific research to better understand and quantify the degree of this threat on our indigenous bird species.
These potential threats could include;
- Impacts on reproductive success of threatened raptor species due to competition for prey, mobbing raptors during hunting and direct mortality of nestlings and fledglings.
- Impacts on smaller passerine species through increased mortality rates and reduced reproductive success due to predation on adult and juvenile birds and eggs.
- Impacts on other components of biodiversity, including increased predation levels on small reptiles such as tortoises and lizards, small mammals and amphibians, at elevated natural predation levels.
These potential threats are based on many anecdotal reports across the country and increased sightings and frequent reports of Pied Crows engaged in the abovementioned behaviours. However, careful investigation of how humans have influenced the expansion of both the crows range and their numbers needs to be conducted to best evaluate the causes of these potential problems and develop solutions.
Other indigenous Corvid species, the White-necked Raven Corvus albicollis and Cape Crow Corvus capensis are also perceived to impact on indigenous biodiversity through natural predation, however anthropogenic land transformation and climate change can rapidly alter ecological communities leading to increased impacts by different Corvid species. There has been documented range expansion in the Cape Crow and this also requires scientific research to document the rate and scale of expansion and potential impacts resulting from expansion.
BirdLife South Africa does not support the control or poisoning of indigenous Corvid species in any manner whatsoever.
BirdLife South Africa reserves action on this issue until adequate scientific evidence demonstrates the need for appropriate action for threatened species and a full and balanced appraisal of this perceived threat has been completed.