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.
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