Background The aquatic warbler (Acrocephalus paludicola), is by far Europe’s rarest warbler. It breeds in temperate eastern Europe (Poland; Hungary, Germany, the Baltic States, the Ukraine and Belarus) and has an estimated population of 15,000 pairs. This small passerine bird is found in wetlands with sedge and similarly structured marshy habitats. Drainage of such wetlands and destruction of the habitat has meant that this species has declined rapidly. For many years, its wintering grounds were unknown, but recently it was discovered that the bird’s European population spends its winters in Djoudj National Bird Sanctuary in Senegal, with between 5,000 and 10,000 birds present at this single site. Aquatic warblers have been recorded migrating through 13 European countries. Its populations begin the autumn migration to western Africa in July, crossing the Iberian Peninsula, which the species also traverses when returning to the breeding areas in spring. The Nava-Campos SPA, situated in the province of Palencia, in north Spain, is one of the main southerly sites used by the aquatic warbler on this journey, with 187 individuals ringed during the year 2000. It is a wetland (a lagoon of 307 ha, with a total surface area 54,936 ha) recovered at the beginning of the 1990s in an area that was formerly filled with a large interior lagoon which stretched over several thousand hectares. Its charophyte meadows and shallow water provide ideal characteristics to host the populations of aquatic warbler during their stay in Spain en route for western Africa. The site is also host to sizeable populations of other bird species (64 of which can be found in Annex 1 of the Birds Directive) and to valuable stands of vegetation. Objectives The project proposed a series of over 30 actions in order to achieve three main objectives: 1. Enlargement and improvement of the status of the aquatic warbler at the la Nava site. 2. Increase the scientific knowledge of the aquatic warbler and its habitat at La Nova. 3. Increase public awareness of the aquatic warbler and its problems. The surface area of habitat suitable for the species would be extended and general knowledge of the aquatic warbler would be increased; in particular, management of the places where migration occurs that are most favourable to its conservation would be improved. To help achieve these goals, lands would be purchased or rented and restored as an optimum habitat for the species through flooding and various types of management (such as mowing, grazing, removal of vegetation and, if necessary, burning). Measures would also be applied to prevent the contamination of the wetland from effluent and to regulate visitor access to the site. Monitoring would be carried out to assess the evolution of the fauna and flora of the site. In addition, annual campaigns to scientifically ring the aquatic warblers would be carried out, and two meetings of experts on the species and its habitats would be held. Results In order to achieve objective (1) - Enlargement and improvement of the status of the aquatic warbler at the la Nava site - the following actions were successfully undertaken: • 26.38 ha of croplands was purchased in the surrounding of ‘El Hoyo’ area, in order to restore the available habitat • 68.4 ha of land was leased in the areas known as ‘El Hoyo’ and ‘La Güera’. The LIFE works included the flooding of these grasslands and the planting of 22,000 specimens of Tamarix sp. and Salix sp (native species) in order to both establish boundaries and, increasing the available habitat for the species. • The Fuentes de Nava waste pipeline was buried in order to prevent the spillage of effluent into La Nava lagoon, thus improving the water quality • A wastewater pipeline ‘by-pass’ over ‘La Culebra’ stream carrying effluent from the town of Paredes de Nava was improved. • The flooding system in the northern sector of ‘Cantarranas’ was improved in order to extend by 18.6 ha the habitat available for the aquatic warbler. • Different techniques for the vegetation management in the La Nava lagoon were implemented. These included: mowing, mechanical removal, horse gazing, controlled fire (when necessary). In order to achieve objective (2) - Increase of the scientific knowledge on the aquatic warbler and its habitat in La Nava - the following actions were successfully undertaken: • Botanical monitoring was a key action. Data on the evolution of the botanic communities was produced, and an assessment of the effectiveness of the vegetation management actions was carried out in order to produce vegetation management guidelines. • Ringing campaigns were carried out over the course of the project. These helped to identify more precisely the time of presence of the species in the wetland, the number of specimens registered and their sex and age. During the project period, 274 individual birds were captured and ringed, with a main migration period between the first two weeks of August and the last two weeks of September. The first ones to stop-over are the adults. • Radio tracking was carried out to gather information about the species and its La Nava habitat. Specifically, 12 specimens were tracked using radio transmitters over a 69 working-day period (providing over 400 hours of data). This has provided more precise information about their staying period, their home range and habitat needs. • Species monitoring was carried out in order to identify which areas of the wetland are the most favoured by the species. This has also helped to determine population densities and, of great significance, an evaluation of the vegetation management was carried out. • A meeting of experts in helophytic vegetation management was organised by the beneficiary in August 2003. This was the starting point for the production of the project’s management guidelines for wetlands hosting the aquatic warbler. • An international seminar on the conservation strategy for the species was held in August 2005. This enabled an exchange of the latest knowledge about the conservation and biology of the aquatic warbler in Europe, with special attention paid to the new research into migratory routes and stop-over sites studied and the new discoveries of the western African wintering range. In order to achieve objective (3) - Increase of the public awareness on the aquatic warbler and its problems - the following actions were successfully undertaken: - a DVD on the aquatic warbler and the LIFE project was produced - the project website was created and maintained (www.carricerincejudo.org) - various dissemination material was produced e.g. leaflets, T-shirts, stickers and pins and exhibition panels - a manual on the results of the vegetation management and scientific monitoring works undertaken was published - a visitor path was constructed (this was partially completed) to satisfy visitor demand without disturbing fauna. In total, some 32 actions successfully introduced over the project life-time, which together has greatly benefited the conservation of the habitat of the target species, the aquatic warbler, and also the overall ecosystem of La Nava wetland. According to the beneficiary, thanks to LIFE co-funding, knowledge of the species and of its problems has been greatly enhanced, especially at the local and regional scale. Looking to the future, biotope management and monitoring works will continue after-LIFE. The ringing and monitoring actions on the target species will also continue after official closure. Funding will come from the regional administration and, possibly, from private sources.