We analysed images shared to two UK-based waterbird hunting groups between 2019 and 2024. From each photo we attempted to assign the species, age and sex of harvested waterbirds using plumage and bill characteristics. We used this data to assess the ability to monitor the age and sex ratios of harvested waterbirds, and also to estimate the proportions of waterbird species in the national harvest. These proportions can be used to pro-rata national level estiamates of total waterbird harvest when the harvests of individual species are not reproted in countries such as the UK. Our data includes records on the date of harvest and where possible the species, age and sex of all waterbirds present in the harvest photos. This data attempts to minimise externalities such as post-harvest guilt, prestige bias, cultural barriers – thus being as representative as possible of the structure of the UK waterbird harvest.

Digital photographs of hunting bags from two UK specific Facebook groups focused on duck and goose hunting (“Flight Pond Duck Shooting and Conservation” and “Foreshore wildfowling & flight pond Shooting, Management And Conservation”) were analysed for the 2019/20 to 2023/24 hunting seasons. The research proposal to undertake this work using submission to the groups as consent to use the data in the photos was reviewed and approved by the University of Essex ethics committee (ETH2122-0809; see discussion). For each Facebook group, each post was viewed and analysed between January and December 2024. For each photograph we (ME) recorded the date the photograph was submitted, all ducks and geese were identified to species and we attempted to age each species using plumage and bill characteristics. No attempt was made to determine the sex of geese from photographs, but the sexing of ducks was attempted using plumage characteristics as above. Photographs accompanying adverts for hunting opportunities were excluded from the analysis, and where a user submitted multiple photographs on the same day only the photograph with the most individual birds was included unless photographs were clearly from different hunting trips (for example different hunters, different clothes or different vehicles). Where users reported a specific number of birds harvested but the accompanying photograph showed fewer individual birds the additional unphotographed birds were recorded as unknown. Where species, age or sex identifications were provided along with the photographs we recorded them and assessed whether they were correct. Finally, where provided, we recorded the number of hunters who contributed to the harvest shown in the photographs and recorded the data as missing if not reported.