Abstract
Rose-ringed parakeets (also known as ring-necked parakeets) Psitacula krameri, are native to central Africa and Asia. Following introductions, however, populations are now established in several European countries, as well as Japan and the USA (Lever, 2005). The main UK rose-ringed parakeet populations are currently concentrated in SE England, with five major centres of population, primarily in urban areas, in Surrey, Kent and Berkshire. Transient populations have also been recorded in central, SW and NW England. Rose-ringed parakeets in England are undergoing a period of rapid population growth; the best estimate for the present population is 20,000 birds (National Geographic 2004). The observed growth rate over recent years is amongst the highest observed in current British bird populations, and it is likely this rapid population expansion will continue into the foreseeable future (Butler 2003). Parakeets are now being seen in rural areas rather than the previously typical urban and semi-urban areas, and it has been suggested that it may not be long before they spread into the British countryside (Butler 2003). Rose-ringed parakeets are known, or have the potential, to impose a range of detrimental impacts in their native and introduced range. In its native India, it is considered a major crop pest taking grain and fruit (Ali & Ripley 1969, Dhinsa & Saini 1994). They are potential vectors for a number of diseases, including Newcastle disease, avian chlamydiosis and avian influenza. Rose-ringed parakeets are also potential competitors for breeding sites with other hole-nesting species. In Europe they are included as one of fifteen terrestrial vertebrates on the Daisie (Delivering Alien Invasive Species Inventories Europe) list of one hundred worst non-native invasive species. The continued growth and spread of the rose-ringed parakeet population in England, therefore, has the potential to impose significant economic, ecological and social impacts. There is already some evidence of detrimental impacts in England with increasing reports of crop damage, most notably from fruit growers and vineyards in SE England (e.g. Hamilton 2004). Elsewhere in Europe, a recent study in Belgium revealed a negative correlation between the abundance of rose-ringed parakeets and nuthatches (Strubbe & Matthysen, 2007). The aim of this study is to review the published and unpublished information on the techniques available for managing the detrimental impacts of rose-ringed parakeets, focussing on agricultural damage. This will involve the collation and evaluation of information on those techniques to assess their relative effectiveness, cost and humaneness. In order to conduct such an evaluation it is also necessary to review information on the range and extent of detrimental impacts caused by rose-ringed parakeets. This is because, in addition to the cost of implementation, the cost-effectiveness of any specific control technique will depend on the economic value of the damage and the degree of mitigation achieved by using the technique. The potential impacts of rose-ringed parakeets on native biodiversity (specifically native birds) will be investigated in a separate study. As rose-ringed parakeet populations grow and spread increasing conflicts with agricultural stakeholders; risks to biodiversity and social impacts are likely. It is essential that any future mitigation of such conflicts is carried out in an effective, ecologically sensitive and humane way. This project will focus on the potential impacts to agriculture and on possible management techniques to mitigate those impacts. The study will provide a comprehensive review and evaluation of the currently available control techniques and make recommendations regarding any further research necessary to develop appropriate management strategies. The study will help inform future policy development in respect of the species.
United Kingdom