White-tailed Eagle and Common Chiffchaff longevity records smashed


An adult White-tailed Eagle, identified in the field in 2020 by its ring, has been confirmed as the oldest known individual of this species ever recorded in Britain and Ireland.

The eagle had been ringed as a nestling in Highland Scotland in 1996, ageing it as 23 years and 11 months old.

Furthermore, the oldest known British Common Chiffchaff was caught 10 years, 10 months and 27 days after it had initially been ringed at Rutland Water in July 2009. The typical lifespan of this species is around two years.

A White-tailed Eagle observed in 2020 was found to have been ringed as a nestling in 1996, making it almost 24 years old (Dawid B).

Lee Barber, Ringing & Nest Recording Surveys Organiser at BTO, said: "930,088 birds were ringed by our 3,000 highly trained, licensed volunteers in 2020, a slightly lower total than normal due to the restrictions imposed as a result of Covid 19.

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"The most commonly encountered species was Blue Tit, with 118,771 individuals ringed, Blackcap (66,799), Goldfinch (56,742), Great Tit (54,405) and Common Chiffchaff (46,001). The large numbers of these species ringed allow us to compare how they are faring in different regions of Britain and Ireland, and in different habitats."

BTO Researcher Rob Robinson is one of the scientists who analyses the huge dataset generated by the efforts of these volunteers. He said: "By re-encountering these birds, either through reading of rings in the field or through recapture, researchers can determine whether survival rates are increasing or decreasing.

"These re-encounters of individual birds help improve our understanding of their movements, identifying where young birds settle to breed for the first time and how  pressures such as climate and land-use change, drive population declines. For example, recent BTO analyses based on the 15,000 Eurasian Curlew that have been ringed have shown that survival of adult birds is high, and that action to improve conditions for raising chicks is required."

More information can be found on the Online Ringing Report.