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Bobby Bach Leaves the Dyfi

Posted: Tuesday 29th August 2017 by Karis MWT

MWT - EithaMWT - Eitha

Eitha has started her long journey south

Three days have now passed since we last saw Eitha, the youngest of our three chicks from this year. Our cameras show her leaving the nest perch at 20:14 on Saturday night (26th). It is remarkable to think that she, along with all other juvenile ospreys, are flying south based purely on instinct, leaving behind the safety of the nest and all they have ever known.

Here’s a short video with the last pictures we recorded of Eitha, including her final flight from the nest perch.

Below is the completed migration chart, showing the ages of all Dyfi chicks at migration through the years. Both girls from this year were slightly older than average when they left for Africa, which may have been due to the weather we’ve had of late. Strong southerly winds and rain arrived shortly after Aeron left us; not exactly ideal for osprey migration.

Age at migration of all chicks raised by Monty and Nora (2011-12) and Glesni (2013-17)
MWT - Migration graph

The following graph shows the number of days between each chick fledging and migrating, and there are some very interesting patterns.

It suggests that the eldest chicks are always quickest to leave in broods of three (2011, 2015 and 2017), with middle chicks always taking the longest. In years where only two chicks are raised (2013 and 2014), the youngest chick has always been the quickest to migrate, though not by any substantial margin as yet.

Days between fledging and migration, accurate to the nearest minute! 
MWT - Fledge_Migration graph

Our sample size is still fairly small at present, however, and there are countless numbers of variables that could be influencing the results above. As more data is collected in coming years (and lovely statistical analyses are performed) we may find that no significance to the patterns described, but we won’t know unless we try!

Sibling traits? We can only hope

Eitha captured the hearts of the nation when she hatched back in May, causing widespread concern as she was so much smaller than her siblings and often the last in line to be fed. At the time of ringing, Eitha was only 32 days old, making her one of the youngest chicks at ringing. Despite this, she joined fellow females, Menai and Clarach, in being the heaviest birds we have ever ringed on the Dyfi; weighing in at a very healthy 1710g.

Eitha photographed two months ago at ringing, 32 days old
MWT - Eitha at ringing
 

Let’s hope that Menai and Eitha also share their sister Clarach’s success, should they return to breed in 2-3 years’ time.

Clarach and her unringed partner have managed to raise two healthy boys on her first attempt at breeding up in Aberfoyle, Scotland. Both chicks are still being seen around what remains of the nest, with storms causing significant damage to the structure in the middle of last week. Luckily no birds were harmed and all four ospreys in the family were seen, seemingly unscathed, over the following days.

Keep up to date with Clarach and her family here.

LH0 and LH1 perching on what is left of their nest, thankfully looking none-the-worse after the storm!
MWT - Clarach chicks 2017
 

Got the place to himself

With the rest of his family gone, Monty will now be building up for his own migration. It's not known exactly what prompts the males to leave, and even when comparing his departure dates to those of the chicks in previous years, we are still unable to predict when he will leave with any real accuracy.

In the past two years, Monty has waited around the nest for little over a week following the disappearance of his last chick. If we see a repeat of this then we may well have another four days with him before he heads off, yet again, on his journey south. 

The Dyfi Osprey Project closes its doors for the last time this Sunday, 3rd September having opened for 155 days straight and engaged with almost 40,000 visitors. Live streaming and chat will both be turned off for the year the following day, Monday 4th September, as we call time on another fantastic season for the Dyfi ospreys.

Monty up on the larch perch this morning, will he still be here tomorrow?
MWT - Monty on larch

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