Periodic surveys of machair and associated habitats on the west coast of North Uist, Benbecula and South Uist have documented marked changes in the composition of an important breeding wader assemblage. Within the study area of there was a 25% decline in the total number of breeding waders recorded between 1983 and 2022.

Breeding waders in Britain are high profile species of conservation concern because of their declining populations and the international significance of some of their populations. Forest expansion is one of the most important, ongoing and large-scale changes in land use that can provide conservation and wider environmental benefits, but also adversely affect populations of breeding waders. We describe models to be used towards the development of tools to guide, inform and minimise conflict between wader conservation and forest expansion. Extensive data on breeding wader occurrence is typically available at spatial scales that are too coarse to best inform waderconservation and forestry stakeholders. Using statistical models (random forest regression trees) we model the predicted relative abundances of 10 species of breeding wader across Britain at 1-km square resolution. Bird data are taken from Bird Atlas 2007–11, which was a joint project between BTO, BirdWatch Ireland and the Scottish Ornithologists’ Club, and modelled with a range of environmental data sets.

Newly published research by BTO has shed light on the differing fortunes of two small wading bird species breeding in the UK. Little Ringed Plover first bred in the UK in Hertfordshire in 1938. Breeding numbers have increased steadily since, accompanied by a range expansion to the north and west. The species is Green-listed in the UK Birds of Conservation Concern. The Ringed Plover, by contrast, is on the UK Birds of Conservation Concern Red list. Both species were surveyed in 1984, and again in 2007. The new study estimated that the number of Little Ringed Plover breeding in the UK had risen by 71% between 1984 and 2007, to 1,239 pairs. The species’ core range remained in England, although breeding pairs have spread further into Wales, northern England and south and east Scotland. Gravel and sand pits were the favoured habitat for Little Ringed Plover, but its relative importance had declined compared to 1984. The species’ use of shingle habitat had grown, following range expansion into northern and western regions. Over the same time period, the breeding population of Ringed Plover in the UK was estimated to have fallen by 37%, to 5,438 pairs. The greatest declines were reported in England and Scotland, with numbers more stable in Wales, Northern Ireland and the Isle of Man. Decreases were marked in both coastal and inland areas, including at sites where Little Ringed Plover numbers had increased. The two species have similar inland habitat preferences, so the reasons underlying the different trends are not clear. Potential factors contributing to the decline in Ringed Plover at coastal sites include disturbance from human recreational activities as well as habitat change elsewhere. Although the UK populations of both species appear have stabilised recently, greater conservation and protection efforts are required at coastal sites to ensure local breeding numbers are prevented from dropping further.

Protected sites for birds are typically designated based on the site’s importance for the species that use it. For example, sites may be selected as Special Protection Areas (under the European Union Directive on the Conservation of Wild Birds) if they support more than 1% of a given national or international population of a species or an assemblage of over 20,000 waterbirds or seabirds. However, through the impacts of changing climates, habitat loss and invasive species, the way species use sites may change. As populations increase, abundance at existing sites may go up or new sites may be colonized. Similarly, as populations decrease, abundance at occupied sites may go down, or some sites may be abandoned. Determining how bird populations are spread across protected sites, and how changes in populations may affect this, is essential to making sure that they remain protected in the future. These findings come from a new study by Verónica Méndez and colleagues from the University of East Anglia working with BTO. Using Wetland Bird Survey (WeBS) data the study looked at changes in the population sizes and distributions of 19 waterbird species across Britain during a period of 26 years and their effect on local abundance and site occupancy. Some of these species saw steady increases in population size (up to 1,600%, Avocet), whereas other saw mild declines (-26%, Purple Sandpiper and Shelduck). The results showed that changes in total population size were predominantly reflected in changes in local abundance, rather than through the addition or loss of sites. This is possibly because waterbirds tend to be long-lived birds, with high site fidelity and new suitable sites may not always be available. Thus colonisation of new sites may typically occur when their existing sites approach their maximum capacity. As changes in populations are largely manifested by changes in local abundance – and as sites are often designated for many species – the numbers of sites qualifying for site designation are unlikely to be affected. Understanding the dynamic between population change and change in local abundance will be key to ensuring the efficiency of protected area management and ensuring that populations are adequately protected. Data from the Wetland Bird Survey and its predecessor schemes, which are celebrating 70 years of continuous monitoring of waterbirds this year, have been integral to both the designation of protected sites and monitoring of their condition. Continuation of this monitoring through future generations will ensure that the impacts to waterbird populations of future environmental changes may be understood.