Page 61 - State of Biodiversity 2023-2024

House Crow (Corvus splendens) population in the eThekwini Municipality
Article by: Mmatjie Mashao
Email: Mmatjie.Mashao@durban.gov.za
Biological invasion is recognized as one of the most significant threats to modern biodiversity after habitat loss. It is also recognised as one of the leading causes of extinction of indigenous species, mainly birds. As these exotic species arrive in a new ecosystem either naturally or through introduction by human, they can expand their distribution rapidly. This expansion can cause damage to the local environment. One example of alien invasive bird species causing damage to the environment is House Crow Corvus splendens, which has successfully colonised some coastal cities in South Africa, including Durban. Another example of invasive bird species in South Africa includes Common Myna, Rose-ringed Parakeet, Feral Pigeon and Common Starling.
In this report we will focus on the invasive House Crow population within the eThekwini Munucipality. House Crows were first positively recorded in 1972 in Durban and the numbers grew slowly until eradication methods were introduced in 1989. Since then, population size, distribution and damage to the environment by House Crows have been monitored while eradication methods to control the number within the city were explored within the years. A drop in population size was noticed every time an eradication method was introduced, which later increased due to lack of control. Currently, with one eradication method reintroduced by eThekwini Municipality’s Biodiversity Management Department, the number of House Crows within eThekwini Municipality is estimated to be about 700 to 800 birds.
Although the current distribution has not changed much since the reintroduction of the eradication method in 2022. Spread to new locations has been recorded which to some extent shows a connection in movement between the different feeding grounds. When the surveillance of House Crow was reinitiated in August 2019, feeding grounds appeared to be isolated and two populations were evident. One population was in the Durban central area while the other population was in the South of Durban (Merewent and Isipingo area). About 2 birds were recorded in the Pinetown area which later disappeared. When the 2019/2020 observations were compared with 2023/2024, the link between the two populations and
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