Population estimates of non-native rose-ringed parakeets Psittacula krameri (Scopoli, 1769) in the Durban Metropole, KwaZulu-Natal Province, South Africa Tinyiko C. Shivambu 1 & Ndivhuwo Shivambu 1 & Colleen T. Downs 1 Accepted: 5 October 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract Rose-ringed parakeets Psittacula krameri are one of the most widely distributed urban avian invader species present in ~ 35 countries with population sizes increasing. These parakeets were introduced to South Africa as part of the pet trade, and feral populations have established in several urban areas since and are of concern. We, therefore, conducted monthly surveys between August 2018 – December 2019 in the greater Durban Metropole, KwaZulu-Natal Province, to determine their population size and roosting sites. In addition, we recorded bird species that communally roosted with rose-ringed parakeets, and tree species characteristics that they used for roosting. We identified five main roost site areas with an overall mean (± SD) monthly population size of 1 783.3 ± 505.2 rose-ringed parakeets. There was an increase in rose-ringed parakeet numbers, particularly in August and December after their breeding. Most rose-ringed parakeets were recorded in the north, with fewer in the south of the metropole; and many were located around shopping centres and parks. A total of seven bird species communally shared roost sites with rose-ringed parakeets, with the non-native common myna Acridotheres tristis being the species that frequently shared roosts with parakeets. Three tree species were used as roosts, with the Natal mahogany Trichilia emetica and the giant palm Raphia australis, so being the preferred roost tree species. The results showed variations in the measured tree traits and the number of individual parakeets roosting per tree species. The population size of non-native rose-ringed parakeets showed persistent growth, and it is, therefore, suggested that control measures for this species are introduced before its population expands further. Keywords Biological invasions . Avian species . Management . Urban greenspace . Urban conservation Introduction Urban areas have become a global hotspot where different non-native species are introduced for reasons such as pet trade, ornamentation, research, and food (Symes 2014; Gaertner et al. 2017; Padayachee et al. 2017). Consequently, some of these species establish feral populations and become invasive often with environmental and socioeconomic impacts (Magnino et al. 2009; Hernández-Brito et al. 2018; Shiels et al. 2018; Shivambu et al. 2020). For example, parrot species such as monk parakeet Myiopsitta monachus , Alexandrine parakeet Psittacula alexandri, and rose-ringed parakeet Psittacula krameri have established in several cities around the world and are reported to cause agricultural, infra- structural, and ecological damage (Strubbe and Matthysen 2007; Neo 2012; Rodríguez-Pastor et al. 2012; Surender et al. 2016; Shiels et al. 2018). The rose-ringed parakeet often occurs around human hab- itation (Grandi et al. 2018; Mentil et al. 2018). It is a social species and is native to parts of eastern and southern Asia and from eastern to central Africa (Parr and Juniper 2010). Humans have been responsible for translocating this species across the globe as part of the pet trade, and many are pur- chased for companionship (Menchetti et al. 2016; Vall-llosera et al. 2017 ). The rose-ringed parakeet has generally established in its invasive distribution range because of inten- tional release or unintentional escapes of captive populations * Colleen T. Downs downs@ukzn.ac.za Tinyiko C. Shivambu shivambucavin@gmail.com Ndivhuwo Shivambu ndivhuwomaligana@gmail.com 1 Centre for Excellence in Invasion Biology, Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa Urban Ecosystems https://doi.org/10.1007/s11252-020-01066-3