Beached bird surveys in The Netherlands summer 2022 & winter 2022/23, RWS Centrale Informatievoorziening BM 23.16.
Camphuysen, C.J. (2023). Beached bird surveys in The Netherlands summer 2022 & winter 2022/23, RWS Centrale Informatievoorziening BM 23.16. NIOZ Royal Netherlands Institute for Sea Research: Texel. 1-31 pp. |  |
| Abstract | This is the annual report on beached bird survey (BBS) combining results obtained in The Netherlands during summer 2022 (May-Oct) and the winter 2022/23. Summer 2022 was a particularly turbulent season, with HPAIV H5N1 virus outbreaks affecting seabirds all over the Northern Hemisphere. Within the Netherlands, coastal colonies of Sandwich Terns Thalasseus sandvicensis were severely affected. Elsewhere in Western Europe, Northern Gannets Morus bassanus and Great Skuas Stercorarius skua were among the most severely affected populations. In this report, summer strandings of (most probably) affected birds within the Netherlands are summarised. No major die-offs of waterbirds occurred in coastal areas, affecting mainly wildfowl, waders, and raptors, as a result of a highly pathogenic avian influenza (HPAI) virus, H5N1, even though further mortality was expected given the dramatic summer of 2022, which turned out to be a peak in an epidemic season that began in autumn 2021 in Europe affecting seabirds on a grand scale for the first time. Winter 2022/23 was another mild season overall, without really turbulent weather affecting the entire North Sea Area, and this might explain why only one minor seabird wrecks was witnessed (Blacklegged Kittiwakes in mid-winter, one of which oiled). The significant declines in (winter) oil rates of pelagic seabirds, such as these reported in recent decades, especially since ~2005, continued, and only very few oiled auks found in winter 2022/23. The sample size for Common Guillemots was considerably smaller than one year before, and in fact insufficiently large for the Dutch contributions of OSPAR subregions 8 and 10 covered in this study that are bordering the North Sea, but sufficient for subregion 9 and for the Dutch North Sea beach area as a whole. The oil-rate (percentage of oiled Common Guillemots of all complete Common Guillemots found dead) arrived at a very low value of only 0.8% (n= 122) for Dutch contributions to the OSPAR areas 8-10 combined; the lowest value ever measured within The Netherlands. The most recent data conform the declining trend once more, as a result of which the 5-year running mean of oil rates in Common Guillemots has now arrived at 3.3 ± 2.7% (mean ± S.D.) for all North Sea beaches combined. The OSPAR target of 10% over periods of at least 5 years for 2030 has been surpassed already. |
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