BTO Cymru

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Monday, 11 July 2016

30 Not Out

Not cricket, but Ospreys.

May 2004 was memorable, for that was when Ospreys were found to be nesting in the Glaslyn valley, in Snowdonia. As I was the local police wildlife crime officer, and the coordinator of the local raptor workers, there followed for me an initial period of elation, followed by exhaustion, and ultimately depression, when the nest collapsed following an unseasonably heavy hour of rain. At this point, we found that there had been two chicks in the nest, but 10 day old birds could not survive an 80 foot fall through a pine tree.

The male “Ochre 11/98” was a part of the Rutland reintroduction programme; the female was un-ringed, but quite distinctively marked, and has since been christened “Mrs G” .

In 2005, both birds came back and three eggs were laid. Two of these hatched and were subsequently ringed before fledging. So began a dynasty. 

The un-ringed female has returned every year since. To date, 28 chicks have fledged from this nest, the latest being ringed on July 3rd. When they fledge they will bring the total up to 30.

Currently two of her siblings – “YA” and “37” - are nesting in the Kielder Forest, with “Black 80” nesting at Threave in south west Scotland.. At the time of writing, these offspring have produced 41 fledged young, with 11 of this year’s chicks waiting to fledge.

“Black 80” is currently rearing four chicks - a very unusual occurrence.

None of this information would have been available were it not for the efforts of the ringers, and all the dedicated Osprey followers and supporters who have spent so much time watching, and reading the colour rings on these wonderful birds.

Modern technology has told us so much about bird migration, but, for population dynamics like this, colour ringing is still producing the goods, allowing a legion of people to be involved and to contribute to this project. As I say to all our volunteers, you may not think your little bit of data is important, but when we pool it all together we can make meaningful science out of it.

Thanks to Heather Corfield for diligently recording all the ring sightings across Wales and those of the siblings of the original Welsh birds.

For more information about the Glaslyn Ospreys, see

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