Way back in 1985, my diary for 30th June records that I was monitoring golden eagles in the north Inverness glens with my daughter Rona, home from Uni. We climbed to an eyrie near Cannich, which I had monitored for many years, and ringed a single eaglet – ZZ0005. I also attached two small yellow wing tags but the eagle was never identified alive. In fact like most ringed eagles nothing more was heard of it – until out-of-the-blue, I received two emails yesterday. One was from the BTO ringing scheme and the other from Gabriela Peniche, a PhD researcher on golden eagle health at the Dick Vet at Edinburgh University.
The remains of this eagle had been found near Loch Assynt in Sutherland on the 10th August and sent to the lab. It was thought it may have been dead for about 6 weeks and a male. The cause of death was unknown, but there was bruising in the skull and a suggestion of starvation. This is a ‘safe’ area for eagles, free from illegal persecution. My view is that a likely end to a very old breeding adult, of either sex, is to be defeated or killed during a challenge by a young adult to take over a nesting site. That’s how nature works for long-lived raptors.
The BTO Ringing Scheme longevity data gives the present longest recorded life of a ringed golden eagle as just over 16 years – a Kielder Forest chick 29th June 1991 found dead in the Scottish Borders 7th August 2007. In some ways this bird’s death stimulated the South of Scotland Golden Eagle recovery project started this year. In Europe, the Euring database records longevity records for two Swedish ringed golden eagles at 31 years and 32 years, while 23 years is the oldest record in the United States. So ZZ0005 at 33 years appears to be the oldest recorded ringed golden eagle in the wild in the world. There is a record of a captive one reaching 46 years, while very expert fieldwork on breeding pairs of golden eagles on the Isle of Skye by my old friends Kate Nellist and Ken Crane gave an annual adult survival rate of 97.5% suggesting that some adults could reach 40 years of age.
From its recovery location, it may have been the local breeding adult male living in a home-range some 90 kilometres north of its natal site. I know those local eyries from my eagle fieldwork in the 1970s and 1980s. By 2010 Doug Mainland had ringed 18 young at this location since 1990 (when ZZ0005 was five years old). On 17th June 2010 I visited the eyrie with Doug, Derek Spencer and Lorcan O’Toole, who collected one young for the Irish Reintroduction Project. The other eaglet, a male, was satellite tagged and named Suilven: to read more click here. There’s just a chance that ZZ0005 may have been its male parent. This eaglet ranged widely when young, even briefly visiting Skye but when sub-adult returned to an area just east of its natal nest. In the spring of 2015, when Suilven was 5 years old the transmitter fell off (as they are meant to do) and we guess he may still live and breed in that area of Sutherland. It’s lovely to think what a couple of emails can do and how worthwhile was that hike up the mountain in 1985. Bird ringing at its best.
