Workshop report:Development and consequences of the recent bird flu outbreak among Sandwich terns in the Wadden Sea and adjacent areas

The breeding season of 2022 was characterised by a massive outbreak ofhighly pathogenic avian influenza (HPAI), which affected many waterbirdpopulations in NW Europe. In particular, Sandwich terns (Thalasseussandvicensis) suffered major losses in the Wadden Sea as well as in the UnitedKingdom, Belgium and parts of France, Denmark and Sweden. Consequently,the Common Wadden Sea Secretariat (CWSS), as the coordinating unit forTrilateral expert groups on breeding and migratory birds, together with theWadden Sea Flyway Initiative (WSFI) organized an online workshop on 18-19October 2022 to discuss the possible drivers of the outbreak, its consequenceson Sandwich tern populations and future management options. The primarypurpose of the workshop was to bring together a wide variety of multinationalstakeholders, including biologists, virologists, site managers, and decisionmakers to share their knowledge and to better prepare for future outbreaks.Over two days, more than 70 participants addressed three main topics:(1) status of knowledge on the recent HPAI outbreak in Sandwich terns; (2)future management measures, and (3) the effect of the outbreak on Sandwichtern populations. The agenda of the first day of the workshop includedupdating the participants on the current knowledge and status of the recentHPAI outbreak and the measures taken in different colonies and countries,followed by knowledge exchange on the general effect of bird flu on wild birdsand transmission mechanisms. Participants from Germany, The Netherlands,Belgium, France, the United Kingdom, Sweden, Poland and Denmark sharedinformation on their data, experiences, and management measures takenduring the HPAI outbreak in Sandwich tern colonies. On the second day,participants distributed themselves across three groups to address in detailand summarize the following themes: (i) state of knowledge; (ii) managementoptions; and (iii) population modelling