A study led by BTO, working with the Wetland Bird Survey (WeBS) partners, JNCC, RSPB and in association with WWT, provides detailed information on the importance of Great Britain for waterbirds each winter. The work gives revised population estimates for 98 different species that winter in Great Britain, using data collected by many thousand birdwatchers to calculate either the average peak winter population over a five year window between winters 2012/13 and 2016/17, or the most recent possible estimate. Overall, Britain is estimated to host 12.8 million individual waterbirds each winter. The results suggest that geese are doing well while waders are declining - the estimated total number of geese wintering in Britain increased by approximately 175,000 since the previous assessment eight years ago, but waders were down by approximately 142,000 birds. The upturn in geese was largely driven by an increase in Pink-footed Goose by 150,000 individuals, while the wader downturn encompasses falls in numbers of Knot, Oystercatcher, Redshank and Curlew. The study also produced estimates for Cattle Egret, Sandwich Tern and Glossy Ibis for the first time, as well as January-only estimates for 48 species, which are important because January is the focus of global waterbird monitoring via the International Waterbird Census. Waterbirds are a diverse group, and this work involved a range of methods and novel analytical techniques to generate the best possible estimates for each species. WeBS data were used for species commonly found on WeBS sites, such as Dark-bellied Brent Goose and Gadwall, along with extrapolation factors to compensate for birds on non-WeBS sites. For species that prefer the open coast, such as Turnstone, Purple Sandpiper and Great Northern Diver, observations from the Non-estuarine Waterbird Survey (NEWS III) were used. Importantly, this work developed statistical models to generate estimates for some of the most widespread species, for example Teal, that occur on small waterbodies often not routinely counted in WeBS and other surveys. This work summarises data gathered by thousands of birdwatchers across Great Britain, who spent a huge number of hours in the field. As well counts collected by 2,900 WeBS volunteers on WeBS Core Counts and supplementary visits, data gathered by the WWT/JNCC/SNH Goose & Swan Monitoring Programme (GSMP), 860 participants in the 2015/16 NEWS III survey and 600 participants in the BTO Heronries Census were used. More information extracted from specialist reports, BirdTrack and almost 100 county bird reports relied upon countless additional hours by many thousands of birdwatchers, county recorders and bird club committees to collect, digitise and summarise information on wetland birds. Thank you to everybody who contributed to this study – every record counts!

Since 1986, seabird populations in the UK and Ireland have been monitored through the Seabird Monitoring Programme coordinated on behalf of partnership organisations by JNCC. Sample data on breeding abundance and breeding success of seabirds are collected from a large network of sites, both regionally and nationally, to enable species’ conservation status to be assessed. To examine trends at individual colonies, at country level and across the whole UK, it is essential that individual sites can be monitored consistently for many years. Data on breeding abundance – the number of breeding pairs or individuals – provide a medium to long term measure of how populations are faring. Data on breeding success/productivity – the number of chicks fledged per breeding pair – are regarded as short term or more immediate measure of population status. Studies at four key sites (Isle of May, Canna, Fair Isle and Skomer) provide information on adult survival, diet, phenology used to help to diagnose the changes in abundance. Additional information on survival rates at other sites is collected through the BTO’s Retrapping for Adult Survival (RAS) scheme (Horswill et al. 2016), although there are no current RAS sites in Northern Ireland. The SMP generates annual indices of abundance and breeding success from these data which are expressed as a percentage of the population recorded at sites in 1986 when standardised monitoring began (JNCC 2016). Where possible trends are given at the scale of the UK or country level, but where coverage is only possible at individual sites, the indices are shown at the site level. The SMP is a vital programme for monitoring seabird population trends between the full national censuses.