The BirdTrends 2020 report is a one-stop shop for authoritative information about the population status of the common breeding birds of the wider UK countryside. The report is based on data gathered by the many thousands of volunteers who contribute to BTO-led surveys.

New research examining the relationship between the availability of young woodland and two declining species - the Tree Pipit and the Lesser Redpoll - indicates that while important, young woodland availability is not the primary driver of population trends in these species. New research by the BTO, RSPB Science and Natural England has examined the relationship between the availability of young woodland and the breeding population trends of two species on the Birds of Conservation Concern Red List – Tree Pipit and Lesser Redpoll. The availability of young woodland in the UK is largely dictated by national programmes of woodland planting and felling, which peaked after the middle of the twentieth century. Young plantations are considered to provide important breeding habitat for both Lesser Redpoll and Tree Pipit, which underwent sustained and substantial population decline and breeding range contraction, starting in the 1970s. The study used data from the 1988-91 and 2007-11 Bird Atlases, the Breeding Bird Survey and statistics from the Forestry Commission to show that population declines in England were strongly associated with decreases in the availability of young coniferous woodland, and were more weakly associated with an increase in young broadleaved woodland. Abundance was also related to availability of young woodland at the 10-km square scale. However, overall the results suggested that young woodland availability is not the primary driver of population trends for these species. Other factors, such as pressures experienced outside the breeding season, must therefore also be important. More research is needed to better understand the requirements of these species so that they can be conserved and their population declines reversed.

New research by the BTO and the University of East Anglia uses information from the Nest Record Scheme to investigate changes in Willow Warbler breeding between the 1960s and the present day. Despite advances in the timing of egg laying, there has been little change in Willow Warbler productivity over this period. New research by the BTO and the University of East Anglia makes use of the incredible amount of information collected by volunteers taking part in the Nest Record Scheme to investigate the consequences of shifts in timing of breeding for productivity in Willow Warblers. Using information from nearly 7000 nests collected between the 1960s and the present day, this study quantifies changes in the timing of laying dates and seasonal variation in both productivity and timing of breeding (i.e. the proportion of birds nesting at different points in the season), to assess the influence of these factors on changes to overall productivity. In both north-west Britain (where populations are stable) and the south-east (where populations have declined), Willow Warblers are laying their eggs earlier, and such early nesting attempts fledge a higher number of chicks than those laid towards the end of the season. However, these advances have not lead to an increase in overall productivity, as while the proportion of early-season nests has increased, the seasonal decline in productivity in the north-west has reduced and consequently overall productivity is stable. In the south-east, however, the seasonal decline in productivity has increased and, despite the advance in timing of breeding, overall productivity has declined. While shifts in the timing of breeding of migratory species are widespread, this study highlights that the consequences for breeding success at the population-scale will depend on both the seasonal pattern of nesting dates (which will be influenced by the dates that birds arrive from their wintering grounds, environmental conditions for breeding, nest failure and re-nesting) and on seasonal variation in productivity. This means that despite breeding success often being highest at the start of the season, advances in laying dates do not necessarily lead to an increase in productivity. Therefore predicting the population-level consequences of phenological changes requires further research to understand both the mechanisms driving seasonal variation in timing of breeding and its success.