How long do Red-throated Divers live for?

Dave Okill of Shetland Ringing Group writes:

On  26 April 2018, Mick Mellor was doing a routine Beached Bird Survey for SOTEAG (Shetland Oil Terminal Environmental Advisory Group), when on Urafith beach, North Mainland, Shetland he found a freshly dead Red-throated Diver (RTD) that had a ring on it. He carefully noted the number and emailed me when he got home. 

Not remembering the number, I started to look back through old, almost fading, files and I found that I had ringed it as a large chick on a small remote lochan not far from Nibon, North Mainland, on 27 July 1985. At well over 32 years old, this individual was an old bird. Looking at the BTO longevity records, the oldest-known RTD was a bird ringed in Hoy, Orkney in July 1986 and last caught at the same location in April 2015, 28 years, 9 months and 7 days later; our bird clearly beats that by some margin! Searching through North American and other longevity lists, it seems that our bird is probably the oldest RTD yet recorded anywhere.

Ringed Dead Red-throated Diver, Urafirth Beach, Shetland. Photo by Mick Mellor.

As well as demonstrating essential information on migrations, movements and dispersal, ringing also gives us the ages of different species; both the average age and the maximum age of the oldest individuals. Longevity records usually creep up slowly, so an increase in the maximum age of RTDs by four years is a notable leap. I suspect that divers are long-lived birds and this record will be well beaten in time.

The ringing site and the finding place are only a few kilometers apart and it is likely that this bird was a male returning in spring to nest in its natal area. Male divers return to breed close to the area where they fledged; females disperse widely before they breed and Mainland-ringed females have been found many kilometers from their fledging loch, up to the North Isles and as far as Orkney. Orkney females have also been found breeding in Shetland.

Red-throated Diver. Photo by Manuel Schultz/BTO.

Over the years our bird will have traveled widely but we only know two points in this bird's life. To help us understand divers better, JNCC are promoting a project to discover what divers are doing, especially on their wintering grounds, now especially important with the proliferation of vast off-shore wind farms which displace wintering and moulting birds from their traditional areas. Birds from Orkney, Shetland, Finland and Iceland will be investigated.  

Editor's note: all recoveries of ringed birds help to further our knowledge, so if you find a bird ring, please report the details at www.ring.ac. 

Longevity gets even longer

Dave Okill writes:

"During the summer three ringed birds have turned up in Shetland that have beaten the age records in the BTO files for the longest living individual of that species.

The first was a Storm Petrel. Originally ringed on Fair Isle on 29 July 1974, it was then recaught on Mousa 26 May 2010, making it just short of 36 years between ringing and being found again. As Storm Petrels don't usually come back to the North Atlantic until they are 2 years old, then it's likely this bird was at least 38 years old. The previous oldest recorded Stormie was 31 years and 11 months old so this record has increased the longevity considerably.

The next was a Whimbrel on Fetlar that was posted previously here.


The third was a Red-throated Diver. A bird that I'd ringed as a chick on Unst in 1986 was found breeding a couple of kilometres from the site where it fledged, now 24 years old. Male Red-throated Divers starting to breed usually return to a site close to where they were hatched but females disperse more widely.

As all of these birds are still going, it could be that if we hear of them again they will extend the records further."

Thanks to Dave Okill for letting us know and to Malcolm Smith for the photo.