Abstract
This report documents the status of 111 species and subspecies of rare or scarce native birds that bred, or showed signs of breeding, in the UK in 2021. This is by far the highest number of taxa reported on in a single year by the Rare Breeding Birds Panel, and includes the first occurrence in these reports of Marsh Sandpiper Tringa stagnatilis,Elegant Tern Thalasseus elegans and Dusky Warbler Phylloscopus fuscatus. More significantly, it was a good year for many species of heron and their allies, with continued increases by colonisers such as Great White Egret Ardea alba and Cattle Egret Bubulcus ibis. There were new record totals for four raptors and three northern wader species. Furthermore, Temminck’s Stint Calidris temminckii very likely attempted to breed in the UK for the first time since 1997. However, both Montagu’s Harrier Circus pygargus and Yellow-legged Gull Larus michahellis failed to breed for the second year in succession.This is the 48th report published by the Rare Breeding Birds Panel (RBBP) and includes records of the 111 rare or scarce native taxa that bred, or showed signs of breeding, in the UK in 2021. In addition, Appendix 2 summarises the records received for 12 rare, non-native breeding species. Although reporting by the RBBP to date covers 48 years, the Panel is celebrating its 50th anniversary as an independent body in 2023; so, in addition to summarising rare breeding bird activity in 2021, this report looks back over the last half century at changes in both how the RBBP works and the bird populations on which the Panel reports.