Slow-breeding seabirds face an uphill battle to recover from significant losses, scientists express deep concern
Photo for representation: iStock The deadly H5N1 bird flu has wiped out a significant bird population in the United Kingdom, according to a new report.
The Royal Society for the Protection of Birds (RSPB) and other conservation bodies collaborated on the highly pathogenic avian influenza (HPAI) Seabird Survey Report, which highlights the devastating impact on high-, medium-, and low-priority bird species.
The latest data reveals a grim scenario, comparing estimated bird numbers and colony counts to the pre-HPAI baseline figures from 2023. The study accounts for the loss of bird species and colonies between 2021 and 2023, following the initial outbreak of H5N1 in the UK.
Great skuas, in particular, suffered a staggering 76 per cent decline, the authors of the report stated. “As many as 21 of our 25 regularly breeding seabird species have tested positive for the virus, and tens of thousands of seabirds have died,” noted RSPB.
Among other alarming statistics, the report disclosed a 25 per cent reduction in the northern gannet population in surveyed UK sites, which is home for more than half of the species population.
The decline extends to breeding numbers, with a 25 per cent decrease in the breeding numbers of gannets across UK sites in 2023, accompanied by 11,000 deaths in Scotland alone during the 2022 breeding season.
The report emphasised the alarming nature of these declines, either exacerbating previous trends or reversing positive population increases seen before the HPAI outbreak. Nine species experienced declines of more than 10 per cent in overall numbers. This including the common tern (42 per cent decline) and sandwich tern (35 per cent decline), experienced declines of more than 10 per cent in overall numbers.
Widespread declines were observed across UK sites, with great skua decreasing in 88 per cent of occupied sites, common tern in 71 per cent, lesser black-backed gull in 62 per cent and sandwich tern in 57 per cent of sites.
However, the report cautioned against interpreting population changes without considering species' pre-existing trends. Some, like guillemot, Arctic skua and Leach’s storm-petrel, were already on a declining trajectory two decades before the HPAI outbreak.
Despite the complexity, the report attributed the specific declines in great skua, roseate tern and gannet solely to the HPAI outbreak, as these species were reportedly experiencing population growth before significant declines between two to nine years post-2000 seabird census.
Apart from HPAI, the report highlights other threats to UK seabirds, including invasive species, habitat loss, forage scarcity, bycatch and infrastructure development from offshore energy generation.
The scientists expressed deep concern over the slow breeding rate of seabird species, coupled with the extended time required for maturation and reaching breeding age. With these species producing only one or two chicks per year, the recovery of lost populations poses a formidable challenge.
On a positive note, the report mentioned evidence of some seabirds developing immunity to bird flu, including gannets, european shags and sandwich terns. However, the duration of this immunity remains uncertain.
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