Welsh Chick Info

The key facts about Welsh ospreys from 2004 to 2017:

Number of known Welsh nests to date : 6

Number (cumulative) of individual breeding birds at those nests: 13

Number of those 13 that are/were ringed: 4 (31%)

Number of chicks hatched: 83

Number of chicks fledged: 74 (38 female and 36 male)

Number of chicks re-spotted as returned to the UK as adults: 11

Number of those Welsh offspring breeding as adults: 6



Detail of all Welsh Osprey chicks tha have fledged since 2004


Here are a few things to bear in mind:

  1. All except one of the chicks have been ringed and weighed - there are 74 in all. The ring colours are represented by the actual colours used in the table.
  2. Not all the nests are monitored 24hrs a day so therefore it's not possible to know the exact dates for some key events like age at ringing and fledging.
  3. In all, there have been five active nests in Wales, we've numbered them ON1, ON2 etc, ON meaning osprey nest. They are numbered in chronological order, so the higher the number, the more recent the nest is. ON4 and ON5, the most recent, are not in the public domain so are not called by their place names like the Glaslyn and Dyfi nests for example. See below the table for the ON nomenclature.
  4. The gender of each chick is established when the bird is around four of five weeks old when they are ringed. Weight, wing length, leg girth and general 'feel' of the bird to the ringer are all taken into account, but this is only a guess at the end of the day. Sexing young ospreys is not an exact science and is approximately 90% accurate.


Returning birds in detail:

15 Welsh offspring have returned to the UK (and Denmark!) as adults

MWT Welsh chicks data 2019


Of the returning birds 14 Welsh birds:

  • Eight are from Glaslyn (ON2) 
  • Two are from ON4  
  • Four are from the Dyfi nest (ON3) 

Six of these returning birds have bred sucessfully in the UK they are:

  • Glaslyn Yellow 37, 2005 male - breeding at Kielder Water, Northumberland, England.
  • Glaslyn White YA, 2007 male - breeding at Kielder Water, Northumberland, England.
  • Glaslyn Black 80, 2006 male - breeding at Dumfries and Galloway, Scotland.
  • Glaslyn White YC, 2008  male - breeding in Cumbria, England.
  • Glaslyn White 91, 2009 female - breeding in Perthshire, Scotland
  • Dyfi (Blue 2R) Clarach , 2013 female- from the Dyfi nest is the 6th Welsh offspring to be breeding, She is at a nest at Loch Ard, Aberfoyle, Scotland where she produced three chicks in 2017 with an unringed male, they had, two of which survived to fledgling. Both were satellite tracked.  
White YC in Cumbria, 2016 (this is the Foulshaw Moss nest, he actually breeds a short distance away on the Roudsea Moss nest).


The other five returning ospreys that have been re-sighted in the UK but are not as far as we know breeding are:

  • Glaslyn Blue 80, 2012 male. He's been spotted at the Dyfi nest in 2014 as a two year old, and at his ancestral Glaslyn nest in 2015 where he actually bonded with the female there (his own mother) for a few days before being displaced by another male.
  • ON4 Blue 9R, 2014 female. Spotted as a two-year-old in 2016 in Kent (May), County Fermanagh (June) and Ogston in Derbyshire (July)
  • ON4 Blue W6, 2015 male. Sighted at Kielder in 2017.
  • Glaslyn Blue W0, 2015 male.  Sighted at Kielder in 2017.
  • Glaslyn  Blue 9C, 2014 male. Sighted at Leighton Moss, Cumbria in 2017


Blue 9R respotted as a two-year-old adult in 2016

Glaslyn's Blue 80 lands on the Dyfi nest next to Deri, a 2014 fledgling:





If you're up on your osprey ecology and know that ospreys, males in particular, are highly philopatric (return to their ancestral colony to breed themselves), you may well be wondering why on earth all five of these Glaslyn offspring have nested so far away from Wales?

Here's the deal: philopatry works in a normalised osprey population, or one that's nearing being normal at least. When the five birds above returned as two and three-year-olds, there was only one pair of ospreys in the whole of Wales - their own ancestral nest. With both their parents back each year, they had little chance of finding other ospreys in the area so they would have had little choice but to move on to somewhere else. True, they could have built their own nest close by, but they chose not to. Like many large birds of prey, ospreys much prefer to inherit or steal nests (by displacing other, weaker birds) than build their own.


The five Glaslyn offspring chose not to nest close to their ancestral nest


There's a classic case of osprey philopatric breeding-dispersal dynamics at the Rutland Water colony right now. Out of the seven or so breeding males there, every single one of them is a Rutland offspring and these birds have never been spotted elsewhere. In fact, to date, not one Rutland born male (out of 50+ over the years) has ever been spotted back in the UK anywhere other than Rutland, or very near to it.  Classic philopatric osprey ecology in action.

The osprey 'colony' in Wales is much healthier now at four nests, but it is still a species very much in recovery. There's no doubt that we will start to see Welsh males return (and stay) near their ancestral nests in the future, it's a waiting game and one that's not been made any easier by having a glut of females in the last few years!

A youthful looking Tony Cross doesn't quite have the height to ring the first Welsh osprey chick back in June 2004 at ON 1, Welshpool. All other Welsh chicks since have been ringed.