Workshop: Consequences of the recent bird flu outbreak among sandwich terns in the Wadden Sea and adjacent areas

The scale of the recent outbreak of the avian influenza virus among sandwich terns in the Wadden Sea and beyond is unprecedented. While definite numbers are hard to get by in this highly mobile species, many breeding colonies of sandwich terns in the Dutch part of the Wadden Sea have been largely deserted. On Texel alone over 3500 Sandwich Terns have been found dead in June (nearly 40% of the birds breeding on the island), with more animals expected to have died at sea or in areas outside the main breeding sites. From colonies in Lower Saxony, losses of at least 20% among adult birds have been reported.

In the last breeding bird trend report (Koffijberg et al. 2020), the numbers of sandwich terns in the Wadden Sea were estimated to be stable at around 15,000 pairs. However, the species is confined to only few specific breeding sites on the Wadden Sea islands, most of which have been affected by the outbreak. As the colonies in the Wadden Sea represent a large part of the NW-European breeding population and neighbouring colonies have been equally affected (or worse), the deaths of such an extensive number of adult birds can have large-scale consequences for the development of the sandwich tern population. As a result of the high adult mortality, fewer chicks were raised to fledging, meaning that this year’s reproductive success will be reduced.

Exchange of information among experts, representing science, nature conservation and management, is key to better understand how the recent outbreak will affect the flyway population of sandwich terns in the long-term, but also to discuss how environmental and population level parameters may have affected the spread of the virus and what implications this has for the implementation of possible management strategies. Many experts are already in contact with each other, sharing data and information on the newest developments. In consultation with the members of the trilateral Expert Groups on birds, group members from the National Park Lower Saxony and the Common Wadden Sea Secretariat developed a first outline for a bird flu workshop to be conducted in October 2022. In this framework, scientists, site managers, and policy makers working on sandwich terns in the Wadden Sea or adjacent colonies, as well as experts on the bird flu virus and its transmission in colony breeding birds are invited to join a first online meeting on 18-19 October 2022 (noon to noon). 

This meeting will specifically focus on the recent outbreak of the birdflu in sandwich terns. The aim is to learn from each other’s experience in the past months, and to develop a way forward. Thus, we will address three main topics:

1. Regional or colony specific difference in the course of the outbreak? Can we identify specific environmental parameters that affected the spread of the virus? Which management measures have been taken and how has this affected the spread of the virus?
2. In preparation for the next breeding season, which steps shall be taken in the affected colonies? How to deal with future outbreaks?
3. Which population consequences can be expected? Which data are available for population modelling and which additional should be collected in the following year (or during similar outbreaks) to improve our understanding on its impact on the flyway population?

We are planning for a number of presentations linked to the recent outbreak, but also plan for time in breakout groups to discuss the main topics in more detail, giving all participants the chance to contribute to the discussion. If you are interested to give a presentation, please contact Kristine Meise (meise@waddensea-secretariat.org)until the end of August. Please also inform us about any experts you would like to invite to the workshop, so that they can be included in any future communication regarding the workshop. An online survey will be shared in summer with interested participants to help us structuring the thematic focus of the breakout groups.

A follow-up in-person workshop is planned for 2023 which shall not only focus on sandwich terns, but also other species affected by this year’s outbreak around the North Sea.