Every ring carries a unique number and a national scheme holds the record of who fitted it and when. This one goes back to a chick ringed at this observatory fifty one years ago, and the bird in the net is not fifty one.
I am the warden of a bird observatory on a headland. Ringing is the core of what we do and I hold an A permit, which takes about five years to get.
The system is worth setting out because everything here depends on it being exact.
A ring is a numbered metal band. The numbers are issued in series to the scheme, the scheme issues them to ringers, and every ring fitted is reported: the number, the species, the age, the sex, the date and the place.
A retrap is when a ringed bird is caught again. You read the number, you record the biometrics, and you send it in, and the scheme matches it to the original record and tells you where and when that bird was ringed.
That is the whole point. It is how anybody knows anything about how long birds live or where they go.
Ring number, in a series issued to this observatory in 1973.
It was fitted here on the fourteenth of July 1974, to a nestling. The record is in our own log book in a hand I do not recognise and it is in the national scheme's database, and the two agree.
We have retrapped it four times: in 2016, 2019, 2022 and last May.
The species is one that lives about eleven years and whose longevity record for this country is a little under seventeen.
Fifty one is not a slightly surprising number. It is three times the record.
The obvious answer is a ring reused, and I want to deal with it properly because it is what every ringer will say.
Rings are not reused. It is not merely discouraged, it is a fundamental of the scheme, because a duplicated number destroys the value of every record connected to it.
A ring that comes off a dead bird is reported as such and the number is retired.
But rings do get muddled. A number can be misread in the hand, and a five and a six on a worn ring in poor light is a real error, and it happens.
So on the second retrap, in 2019, we did it properly. Two of us read it independently, in daylight, with a hand lens, without conferring, and wrote it on separate slips.
Same number. And I photographed it, and the photograph is legible.
The ring itself.
A ring wears. It thins, the numbering wears shallow, and after fifteen or twenty years on a bird that is in and out of salt water there is often not much left to read.
This one is worn. That is the detail that stopped me sleeping for a week after the 2019 retrap.
It is worn in exactly the way a fifty year old ring is worn: the edges rounded, the metal thinned, the number still readable because the stamping was deep and because that alloy is what it is, and the ring turning freely on the tarsus in a way a well fitted new ring does not.
I have handled rings of every age this observatory has fitted. That ring is old.
The bird.
It is an adult in good condition. It has been an adult in good condition on all four occasions.
Wing length, weight, fat score, muscle score: all within the normal range for the species, all four times, and the numbers from 2016 and last May are close enough to be the same healthy bird.
There is a way of aging some birds by plumage and by the state of the skull, and neither method has a category for what this would be. Both say adult, which for this species means over one year old and means nothing beyond that.
The scheme.
I have reported all four retraps, because reporting is not optional and because I am not going to be a ringer who edits his data.
The scheme's response the first time was the automatic one: date and place of ringing, and the elapsed time, which their system printed as a number of days that runs to five figures.
After the second I got a letter, a real one, from somebody senior. It says the record is being treated as a probable ring number transcription error at ringing in 1974 and has been flagged as such.
That is a completely reasonable conclusion from where they sit. A number written down wrong in 1974 by somebody who is dead would produce exactly this.
It does not explain the wear on the ring.
What I have not done.
I have not taken the ring off. I could: you can remove a ring and fit a new one if the old one is damaged, and a ring that turns that freely could be argued into that category.
I have thought about it every time I have had that bird in my hand, which is four times, and each time I have closed the pliers and put them down and let it go.
The reason I give myself is that removing a ring destroys the record, and this record is either the most extraordinary longevity data in the scheme's history or it is a mistake from 1974, and either way it is not mine to end.
The reason I do not give myself is the other one.
What I do is keep the nets up.
We ring about four thousand birds a year here and I have never once tried to catch that individual on purpose, and I would not know how.
It comes into the same net, which is the third one along the wall on the seaward side, and it has come in the second week of May three times out of four.
I will be on that net this May, with the pliers in my bag where they always are, and the log book, and the hand lens.
And I have started doing one thing that is not ringing and that I would not write in the observatory log, which is that when I let it go I stand and watch it out, all the way, until I cannot see it, instead of turning straight back to the net the way you do when there are forty birds in the bags and daylight is short.