Posted: Wednesday 6th May 2020 by Emyr MWT

Telyn has her first ever returnee offspring back in the UK

Late last night I got a message from Dr. Tim Mackrill. He'd received an email from the Chairman of the Hampshire Ornithological Society, Keith Betton.

They have an osprey near Kingsclere, Hampshire with a blue ring, right leg, Blue KS6.

It's Dinas!!!

Do you have any pictures I asked... "oh, yes" said Keith....


Dinas in Hampshire on 5th May 2020                                         ©Shane King

 

Doesn't he look fantastic?

Dinas is the youngest of three - Alys and Helyg being his older sisters; he hatched on the Dyfi on 3rd June 2018, he's back in the UK a month short of his second birthday. To date, Dinas is the only 'runt' (Bobby Bach) of a clutch of three we've seen return, i.e the youngest of three. However, he wasn't really a runt, he was well fed, he was strong and was independent from an early age.

In fact, 2018 was a record year in terms of shortest hatching spans for any three-egg clutch. Despite there being six days between laying the first and third egg, it took only 1.6 days for all three to hatch.

This is Telyn's 'delayed incubation' strategy at work. Today, for the first time, we can say it has been highly effective.

Here are all the other returnees, now SIX in all (in black bold outline):

(thanks, Vicky)


It's hard to gauge eye colour from one photo, but one thing is clear.... Dinas has very dark underwings - just like his Dad, Monty.

Dinas, despite being the youngest, fledged quite early at 50.1 days old; that's a day and half younger than the average for Dyfi males.

 

Dinas migrated slightly earlier than the average for males too - again, by around a day and a half: 87 days versus 88.5 days.

 

Location

This is where Dinas was yesterday. There is a Rutland female with an empty nest (Blue CJ7) on the English coast at Poole Harbour. If only we could tell Dinas to turn around, he's not that far away...

 

Bobby Bach Bonus

Right, bear with me here...

Between the Glaslyn nest (breeding from 2005 - present) and Dyfi (2011 - present), there have been only seven occasions where we've had a full set of three chicks and they all survived to migration age AND one or more of those three have been subsequently spotted back in the UK as an adult.

 

  • 2008 - White YC (Glaslyn: 2nd of 3 chicks)
  • 2009 - White 91 (Glaslyn: 3rd of 3 chicks)
  • 2012 - Blue 80 (Glaslyn: 2nd of 3 chicks)
  • 2014 - Blue 9C and 8C (Glaslyn: 1st and 3rd of 3 chicks)
  • 2015 - Merin (DOP: 1st of 3 chicks)
  • 2017 - Aeron (DOP: 1st of 3 chicks)
  • 2018 - Dinas (DOP: 3rd of 3 chicks)

So, that's eight birds that have returned from three-chick broods that survived until migration age. Of these:


37% have been the first chicks hatched

25% have been the second chick hatched

37% have been Bobby Bachs - the third chick hatched

 

A small sample size I know, but at least this tells us, to some degree anyways, that the third chick, the Bobby Bach from each clutch, does not seem to be disadvantaged in a significant way.

We have to remember, however, that the ecological rules of engagement are different in a small recovering population like the one we have in Wales. The results could be a lot different in a more normalised and saturated osprey population where competition pressures will be greater.

 


And Finally

So far, six DOP offspring have been re-spotted as adults - out of a possible 19 (up to 2018, the 2019 birds won't be back until 2021).

That's a return rate of 32%, so around one bird in three.

However, these are just the birds we know about, and it's only the first week in May still. Will we see our first two-chick returnees this year, two from the same clutch?

Astonishingly, Dinas is the 5th male out of a possible nine to have returned. The return rate now is 56% (at least) for the males.

A small sample I know, but to get 56% (at least) of our male birds back is off the charts.

C'mon girls, it's your turn next...

Dinas diving in a lake in Hampshire yesterday                                         ©Shane King


Many thanks to Tim, Keith, Tony Cross for ringing our birds every year, photographer Shane King and, of course, all those volunteers that helped protect those three precious eggs back in May 2018.

Here is your reward.

Dinas (right) next to his sister Alys in 2018


 

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