Assessing the vulnerability of wild bird populations to high pathogenicity avian influenza

Vulnerability assessment to high pathogenicity avian influenza predicted mortality at the avian family, but not the species, level. To assess the vulnerability of UK birds to high pathogenicity avian influenza pre-2021/2022 and during the exceptional 2021/2022 season. Two trait-based approaches to vulnerability assessment were tested using surveillance data for the number of reported positive avian influenza detections in the UK. Species-level positive detections varied with population size, body size and colour. Although overall vulnerability assessment was not correlated with positive detections at the species level, components of vulnerability most likely to reflect mortality rates were positively correlated with positive detections pre-2021/2022, but not in 2021/2022. Vulnerability assessment scores were strongly correlated with mean positive detections at the family level (but not species level) in both time periods. Consistency in successfully identifying the most vulnerable avian families suggests predictability in vulnerability, even if species mortality rates vary among outbreaks. Waterfowl, seabirds, other waterbirds and raptors were ranked as most vulnerable. Components of vulnerability most linked to mortality may not be associated with aspects of vulnerability most linked to conservation impact.