High Tide Roost   High Tide Roosts in the Wadden Sea A Review of Bird Distribution, Protection Regimes and Potential Sources of Anthropogenic Disturbance.  A Report of the Wadden Sea Plan Project 34 (WSP § 9.2.1) Wadden Sea Ecosystem No. 16  - 2003 Koffijberg, K., J. Blew, K. Eskildsen, K. Günther, B. Koks, K. Laursen, L.M. Rasmussen, P. Potel, P. Südbeck.  2003. High Tide Roosts in the Wadden Sea. A Review of Bird Distribution, Protection Regimes and Potential Sources of Anthropogenic Disturbance. A Report of the Wadden Sea Plan Project 34. Wadden Sea Ecosystem No. 16. Common Wadden Sea Secretariat. Wilhelmshaven, Germany. Order copy (Euro 6,- plus mailing costs) Contents   (NOTE: PDF download in preparation - available in February  04) Editorial Foreword Acknowledgements Contents Summaries (English, Dutch, German, Danish) 1. Introduction and Background 2. Data and Methods 3. Functional Aspects of High Tide Roosts 4. A Review of Bird Distribution, Protection Regimes and Potential Sources of Anthropogenic Disturbance 5. Species Accounts 6. Discussion and Conclusions 7. References Complete report (pdf, 16 MB)   Title (700 kb) Report (PDF, 16 MB) order report as PDF (16 MB) on CD-Rom  (3 € plus mailing costs)   Summary The Wadden Sea ranks among the most important wetlands to migratory waterbirds in the world. Its vast area of intertidal mudflats hosts numerous bird species breeding in the tundra from arctic Canada in the west to northern Siberia in the east. They use the Wadden Sea either as a stop-over site between the arctic breeding areas and the wintering areas in Africa, or stay in the area to winter. Besides, some species gather to moult in late summer. Most birds staying in the Wadden Sea, feed during low tide at intertidal mudflats and congregate in large flocks at communal high tide roosts. Often, these roosts are found at the edges of salt marshes, on sand flats and beaches or, when foreland is lacking, also at dikes and breakwaters in harbours. Some species also roost at inland pastures and arable fields or in wetlands behind the seawall. The attendance of high tide roosts is highly dynamic and depends, e.g., on actual water tables, distance to the nearest feeding areas, the degree of human disturbance and species-specific behaviour. The safeguarding of high tide roosts is one of the most important tools for the conservation and protection of birds in the Wadden Sea and can be achieved by the targets set in the Wadden Sea Plan. As part of the Wadden Sea Plan and the Stade Declaration of 1997, a special project was launched to investigate the current status of high tide roosts in the Wadden Sea and to present a review of available knowledge of the distribution of waterbirds at high tide roosts, including knowledge concerning the necessity for undisturbed roosting sites. This report presents a detailed overview of distribution of waterbirds in the Wadden Sea during high tide and an inventory of protection regimes and potential sources of anthropogenic disturbance for each site. For this purpose, data from mainly trilateral co-ordinated waterbird counts from the Joint Monitoring of Migratory Birds (JMMB), which are carried out in the framework of the Trilateral Monitoring and Assessment Program (TMAP), between 1990 - 2000 were analysed for species which show tidal movements and depend on high tide roosts. These counts are mainly carried out in the Wadden Sea Cooperation Area, but additionally also include agricultural sites behind the seawall (mainly in Denmark, Lower Saxony and the Netherlands), which belong to the network of roosting sites as well and are especially important during exceptional high tides or for specific terrestrial species like Brent Goose, Golden Plover and Curlew. Data on site characteristics and potential sources of anthropogenic disturbance were derived from available trilateral data (Quality Status Report) and expert estimates on the level of human activities. Special caution was taken to provide a similar approach in estimating these levels in Denmark, Schleswig-Holstein, Lower Saxony and the Netherlands. Roosting behaviour in migratory waterbirds is a complex phenomenon. Gathering in large and dense flocks is thought to minimise the risk of predation for individuals by e.g. Peregrine Falcons, but also saves energy when staying close together at the roost. In a dynamic area like the Wadden Sea, actual water tables, distance to the nearest favourable feeding areas, preferred roosting habitat, site-tenacity and social status of the birds all contribute to the actual number of birds and species observed at a high tide roost. As a result, species often use a network of roosting sites. For a species like Red Knot this network might cover an area of 800 km2 within a short run of tidal cycles. Apart from these natural factors, the level of anthropogenic disturbance is one of the most important factors determining numbers observed at high tide roosts and puts an extra constraint on the birds’ narrow energetic balance and tight time schedule for migration. Case studies in several parts of the Wadden Sea, point out that recreational activities are the most observed sources of disturbance. This is supported by our inventory, which points out that 80% of all roosting sites in the Wadden Sea is subject to some kind of recreational pressure (36% of the roosting sites when considering only moderate to heavy recreational pressure). Moreover, data on phenology show that the seasonal occurrence of some species is affected by moderate and heavy recreation pressure, i.e. birds tend to avoid roosts visited by many people in the summer holiday season. Hunting is observed at many sites as well (up to 33% of all sites in Denmark, when regarding moderate to heavy hunting pressure). Although hunting on migratory waterbirds has been gradually phased out in the Wadden Sea during the 1990s, hunting on small mammals like Hare is still common practise and also occurs at salt marshes, close to high tide roosts. Other sources of potential anthropogenic disturbance, like civil air traffic, military training activities and wind farms occur at a much smaller scale, although sometimes close to important high tide roosts (e.g. Vliehors at Vlieland, the Netherlands, which is situated in a military shooting range). In general, it turns out that the largest roosting sites are a result of large intertidal mudflats at close range and low levels (or absence) of human disturbance. This combination is especially found at remote and uninhabited islands, like Süderoogsand, Trischen (both Schleswig-Holstein), Scharhörn (Hamburg), Memmert (Lower Saxony), Griend and Richel (both Netherlands). The outstanding importance of the Wadden Sea has been acknowledged in several international conventions and directives, such as the Ramsar Convention, the Bonn Convention on Migratory Species and the EC Bird and Habitat Directives. These all have been implemented in the national legislation and the respective protection regimes. When regarding Special Protection Sites of the EC Bird Directive and Ramsar sites, which overlap with most of the national protection regimes, most countries have more than 80% of their high tide roosts located within designated areas (for most species also supporting more than 90% of the birds observed). In the Netherlands and Lower Saxony, this figure is somewhat lower since both countries have a large proportion of inland agricultural areas among their roosting sites, which are subject to limited special protection measures. Only in Lower Saxony, important inland sites outside the trilateral cooperation area have been included in SPA boundaries, whereas in the Netherlands these areas were not taken into account in the last update of SPAs in 2000. Especially species like Brent Goose, Golden Plover and Curlew are known to frequent inland roosts in large numbers. Moreover, inland roosting sites become important for all species during very high water tables, when regular high tide roosts become flooded. In Lower Saxony, Hamburg and Schleswig-Holstein, national protection regimes have been set up by establishing national parks, which include zoning for different human activities. In Denmark and the Netherlands, a similar approach was followed with the introduction of the Nature and Wildlife Reserve and the Key Planning Decision Wadden Sea respectively. However, the actual size of the highest protection zone in these countries is smaller than in Germany. Besides, zoning of recreational activities has not been developed here in detail. The guiding principle of the trilateral Wadden Sea policy is to ”achieve, as far as possible, a natural and sustainable ecosystem in which natural processes proceed in an undisturbed way” (Ministrial Declaration Esbjerg 1991). Three of the four targets on birds, which were agreed upon at the Leeuwarden Conference in 1994, are related to the impact of human disturbance. This report shows that, despite extensive protection regimes, disturbance of roosting birds occurs in all parts of the Wadden Sea. Especially outdoor recreation occurs around many roosting sites and its volume, along with conflicts between tourism and nature conservation, is expected to increase in future (Quality Status Report, 1999). Moreover, recreational activities more and more expand to spring and autumn (although still peak during summer holidays in July and August). As a result, potential conflicts between waterbirds attending high tide roosts and recreational activities around these roosts are especially to be expected in May and in July-October. Both are critical periods to birds as they involve pre-migration and pre-breeding fattening and moulting in late summer. In order to reduce this conflict, a spatial and temporal zoning of recreational activities as well as a convincing visitor information system should be further developed. Besides, more information is needed concerning natural flight distances, which can give feedback in planning public access to areas in the vicinity of roosting sites. For this purpose, also carefully designed experiments should be set up in order to assess the complex relationships between bird numbers and the level of recreational activities. Also it is important to include management of non-waterbird hunting in trilateral protection measures, especially to reduce impact from hunting in salt marshes or inland roosting sites during high tide. Furthermore, the impact of civil air traffic (including ultra-light aircraft), military training activities and wind farms should be assessed in more detail. Civil air traffic has been largely regulated by trilateral standards now, but severe disturbance is still reported from a number of roosting sites. Military training activities occur only at a few sites, but one of these (Vliehors at Vlieland) is one of the most important high tide roosts in the entire Wadden Sea. Establishing wind farms in the Wadden Sea Conservation Area is forbidden now, but conflicts for roosting birds might arise when planning wind farms in inland areas close to the seawall or in offshore areas close to the Wadden Sea. A more careful selection of sites as well as more detailed studies concerning the impact of wind farms for other species than geese is necessary to reduce possible conflicts here. This can also be achieved by a better formal protection of inland roosting sites, which is lacking especially in the Dutch part of the Wadden Sea.