Changing soundscapes. The spread of parakeets in Europe

This is going to be another “noisy spring”. The melodious notes of native black birds, wrens and robins are being progressively replaced in many European towns by the frequent loud screeching calls of monk parakeets and rose ringed parakeets. The genuine “soundscape” of European towns is indeed rapidly changing, replaced by the exotic calls of parakeets, which are becoming a familiar sound in many European cities, particularly in urban areas and parklands. Roosting sites are sometimes spectacular, as they may often contain several hundred birds attracted from a wide area to just a few trees. Nevertheless the screeching calls of parakeets in Europe, rather than being considered a mere novel fascinating thing, should remind us of the actual and potential threats they represent. In the old continent parakeets are not native species, as they have created breeding colonies only recently, further to intentional releases or accidental escapes of animals traded at least since the 60's as cage birds. Like many other invasive alien species, their presence can be detrimental to the environment and human welfare.

Monk parakeet (Myiopsitta monachus) in a cage
© Photo: Riccardo Scalera

Take for example the rose-ringed parakeets. This native to the African continent south of the Sahara and to south Asia, is now the most widely introduced parrot in the world (including at least 12 countries in Europe). In Europe, besides being a clear noise nuisance as already considered in some residential areas, can have a major impact on biodiversity, agriculture and even health. In fact rose-ringed parakeets may have detrimental effects on native birds with which they may compete, particularly in those habitats where the number of cavities as breeding sites is a limiting factor regulating population densities of cavity-nesters (e.g. for species like Eurasian nuthatch,  kestrel, stock dove, western jackdaw and common starling). 

In Europe most rose-ringed parakeet populations were initially introduced in urban environments, thus the impact on agriculture has been historically limited. However, they are now extending their range into rural environments, thus increasing the potential to become agricultural pests. Although the reports of parakeet damage to agriculture are still few, there is clear evidence of significant damage to crops as well. For example, in the United Kingdom rose-ringed parakeets damage buds and blossoms of various trees and shrubs. For this reason conflicts are known with fruit growers that experienced damage to apple, pear, cherries and plums. In addition, this parakeet has been reported to have damaged vineyards by reducing the expected wine production. Also in Australia, where the species is not native, rose-ringed parakeets are known to cause severe damage to plantations by stripping the bark from young stems and killing the affected trees, thus locally changing the arboreal composition. On the other hand, in at least part of its native range this species is considered one of the most destructive bird pests for agriculture. In India and Pakistan, for example, there are extensive reports of crop damage. 

Rose-ringed parakeet eating plums in Versailles
(Psittacula krameri)  © Photo: Riccardo Scalera

Rose-ringed parakeets are also possible vectors for diseases, like Newcastle's disease and cryptosporidium, which could be harmful to poultry and might also have an impact on that industry. Moreover, they could affect humans in the case of psittacosis. In any case, the potential for the parakeets to become serious pests in the future has been highlighted, in fact there is concern that farming practices that adapt to global climate change and a warmer Europe will facilitate the continued expansion of parakeet populations. As a consequence, given the detrimental impacts of parakeets occurring outside their natural range, it would be useful to monitor existing wild and captive populations, and to improve legislation to prevent deliberate introductions and escapes. Moreover, depending on the risks posed, population control or eradication may be considered necessary to limit the spread of the species and the potential for further damage. But this might be not very popular. The experience with the monk parakeet control in London (described here) is a good example of the challenges and opportunities of this option in Europe, with a special focus on the social dimension of the problem represented by this South American parakeet.

A dedicated EU project – ParrotNet - is just being launched with the aim to create a European network focusing on the impacts, drivers and monitoring of invasive parrots in Europe, and promoting the understanding of relevant invasion dynamics and risks to agriculture and society. ParrotNet is a COST Action, led by the University of Kent, UK, and will provide funding for a 4-year research network (for further information see here). The project, comprising currently 14 European countries, will help to (i) better understand why some species such as parakeets are highly successful invaders, (ii) harmonise methodologies to predict agricultural, economic, societal and ecological impacts across Europe, and the means to mitigate them, (iii) create a virtual European Monitoring Centre for all invasive parrot species, and (iv) transfer results to policy and society.  This is a key attempt to prevent that Carson's prophesy of a “silent spring” will be replaced in the near future by a more and more insidious “noisy spring”.

"Union gives strength” against biological invasions

The European Union has just approved an ambitious COST project addressing the threat of biological invasion in the region. The project, which is aimed at the development of a European information system for alien species, is basically built on DAISIE, a previous EU funded project that so far delivered the most comprehensive inventory of alien species in Europe. Aesop’s famous quotation "Union gives strength” is definitely the motto which does better express the great success achieved by DAISIE: in fact this FP6 project could count on the fruitful collaboration of a large number of experts in the field of biological invasions. Similarly, the new COST initiative gathers together an international team of nearly 100 leading experts from over 30 countries, led by NERC Centre for Ecology & Hydrology in the UK.

DAISIE (Delivering Alien Invasive Species Inventories for Europe) was indeed the first attempt to assess the extent of the problem of biological invasions at the European level. The collection and analysis of data relative to over 10.000 alien species recorded in the region allowed to fill in the main knowledge gaps on the issue, including the identification of key patterns. The results showed that the rate of invasion of alien species has been increasing in recent years, and so are the associated costs to society, the economy and biological diversity (including the many impacts on the goods and services provided by ecosystems). They also showed that a unitary regional approach is required to design and implement innovative and cost effective solutions to combat IAS and the problems they cause.

DAISIE portal (www.europe-aliens.org)

Nevertheless the information on alien species across Europe is still scattered in a multitude of databases, plus a number of peer-reviewed articles and grey literature, unpublished research projects or institutional datasets. In fact many other initiatives exist that have contributed to consolidate information into centralised regional or local databases (examples are NOBANIS, REABIC, ESENIAS, MAMIAS, the Baltic Sea alien species database). The problem is that the available databases are severely affected by many constraints that limit their effective use, e.g. data obsolescence, lack of interoperability and uncertainties for long-term sustainability, etc. Besides, there are major differences in their geographic, taxonomic and ecological coverage.

In this context, and in continuity to DAISIE, the new project aims at facilitating enhanced knowledge gathering and sharing. In fact a key task of the new COST project will be the exploration of the existing data gaps to ensure a better harmonisation and validation of information distributed in the available resources, to be efficiently used in early warning system decision tools (through standards developed in DAISIE). The ultimate aim is to support the development of a European information system for effective and informed decision-making in relation to IAS and the relevant EU legislation that is being developed. COST, which is an intergovernmental framework for European Cooperation in Science and Technology, will ensure the project partners to work in close contact with all national and regional alien species networks to ensure a fair exchange of high quality and reliable data and information. The objectives also focus on the need to analyse data and information to assess the impact of invasive alien species and the relevant pathways – thus fully supporting the implementation of the EU 2020 Biodiversity Strategy.

The web-page of the Action can be found at http://www.cost.eu/TD1209