Aspects of the ecology of invasive rose-ringed parakeets (Psittacula krameri) in eThekwini Metropolitan, KwaZulu-Natal Province, South Africa.

Abstract

Globally, the rose-ringed parakeet Psittacula krameri (Scopoli, 1769) has been cited as one of the world’s worst gregarious invasive parrot species, having established breeding colonies successfully outside its native distribution range. The rapid expansion of its breeding population has been considered a major threat to the economy, agricultural production, biodiversity, human health and social life. To date, the rose-ringed parakeet’s population has been reported in ca. 35 countries and the pet trade is the main introduction pathway of this species across the globe. In South Africa, rose-ringed parakeets were introduced as pets in the 1900s. Their breeding population has successfully established in several cities, particularly in Johannesburg and eThekwini Metropole. Although their population seems to be expanding at an alarming rate, little is currently known about their population size, breeding status, and feeding biology. This includes public knowledge and perception towards them as invasive species. Moreover, impacts (environmental and socio-economic) and areas that are at risk of becoming invaded by rose-ringed parakeets and other selected invasive bird species are unknown. This study conducted monthly surveys in the greater Durban (eThekwini) Metropole, KwaZulu-Natal Province, South Africa, from August 2018 to December 2019, to determine the rose-ringed parakeet’s population size, feeding biology and breeding status. A questionnaire survey was developed to determine the public knowledge and perception of parakeets. The species distribution modelling and Generic Impact Scoring Scheme were also used to investigate areas that are likely to be invaded and potential impacts (environmental and socio-economic) associated with rose-ringed parakeets, and other selected introduced bird species. A total of five major roost sites with an overall mean monthly population size of 1,783 rose-ringed parakeets were located. Most of these roost sites were found around urban (public) parks and shopping centres. Seven bird species were found sharing communal roosting sites with rose-ringed parakeets, with the common myna Acridotheres tristis recorded the most. We identified 72 nests within 39 breeding sites, with the first breeding season accounting for 53 active nests and the second breeding season with 59 active nests. Rose-ringed parakeets used four tree species for nesting, with white milkwood Sideroxylon inerme being the most preferred tree species (71%). The recorded rose-ringed parakeet fledglings ranged between 1 – 3 per nest, and their numbers differed significantly between the seasons. A total of 63 feeding sites were identified, with most of them in the urban built land-use cover type. Rose-ringed parakeets were observed feeding on 31 fruiting/flowering trees and one insect species, with fleshy fruits (58%) and flowers (19%) primarily relied on. For our survey questionnaire, a total of 312 participants responded to the survey, with 92.5% being familiar with parakeets. A large population of rose-ringed parakeets were seen in shopping centres (38.5%), suburbia (26.3%), and golf courses (19.6%). Most survey respondents (58.3%) indicated that they provide feeding stations for these parakeets, and 57.7% did not consider them pests. In terms of invasion risk, the rose-ringed parakeets were found to have large areas in South Africa with high climatic suitability, and their impacts were both socio-economic and environmental. Agricultural production was the main impact through socio-economic, while competition and impact on other animals were the main environmental impacts. In general, this study showed continuous growth in the rose-ringed parakeets’ numbers in eThekwini Metropole, indicating that their population is breeding at an average rate. Our study also showed that rose-ringed parakeets feed on various food items, suggesting that they are generalist-opportunistic feeders. As a result, this plasticity in feeding behaviour may likely enhance competitive interactions with other species, contribute to seed dispersal, and increase damage to crops. Parakeets are not perceived as pests by most of the respondents in the eThekwini Municipality. This positive perception may have been exacerbated by the public’s poor knowledge regarding their impacts on biodiversity, economy, human social life, and health. Therefore, we recommend introducing environmental education, which involves the engagement with the community members and eThekwini Municipality. This may assist in making an informed decision regarding the control of this species in the area. Monitoring of rose-ringed parakeet’s population size, breeding status, feeding biology, and movement patterns should continue so that adequate information can be acquired on their biology. In conclusion, our results highlight the importance of studying rose-ringed parakeet’s ecology, which provides reliable data that can be considered in decision-making, management and eradication plans for parakeets in South Africa.