Back to blog listings


Helicoptering Week

Posted: Wednesday 5th July 2017 by Emyr MWT

Aeron, Menai and Eitha will be airborne in a few days.

These next few coming days are, arguably, the most compelling of the whole year.

The torturous, frost-biting work up rickety tower scaffolding in January and February to test and service the season's cameras and mics - just a distant cryogenic memory. Over 40 days of 24hr surveillance burning the midnight oil, peering through matchsticks to ensure the three eggs are safe - we can now laugh at (not funny at the time).

Even the three tiny bobs, desperate for parental attention whilst hardly able to lift the weight of their own heads to feed - it seems like it was a completely different part of the season. Yet it was only the beginning of last month.

Have a look at this short video of Aeron, Menai and Eitha - it was only a few weeks ago..



The Times They Are a Changin'

All three chicks will now have put on most of the body weight they need. Over the next few days we'll see a host of other changes manifest themselves as we near the final stages of transitioning from mere 'chicks' to adults. Well, juveniles anyway. 

Many raptor species have a groove underneath each claw, but the osprey doesn't; they're rounded. Here's Menai and Eitha to demonstrate exactly this..

We'll see big changes in the development of flight feathers - those on the wings and tail. The youngsters will start to stand on their feet more, rather than on their knees. Their voices will 'break'; it's pretty quiet at the nest right now with just Glesni calling out for food now and again. Prepare yourself for an osprey cacophony concert in the coming days, a thunderous, belligerent orchestra of various food-demanding screams that can be heard for miles, literally.

Deri in 2014. Now she could make some noise..

We're seeing changes in the parents too. Monty and Glesni spend less time on the nest now; after all, there isn't much room for five full-size adult birds on the eyrie. Osprey nests are big, but not as big as you read and hear sometimes.

"Osprey nests are as big as a large double bed" is a favourite description from the 80s dragged into the 21st century and still recited over and over. They're not. Natural nests are four, five feet across at most. Man-made nests that are too large when erected are invariably down-sized by the returning ospreys, usually by bringing the 'walls' in. They're quite a bit flatter than you think too.

Ospreys continually adjust their nest throughout the season, depending on their needs

Monty spends more time standing on the ground in July and August, as he did last night. Nothing to be worried about here, ospreys spend time on the ground in Africa too; they're not as arboreal as some other raptors.

Glesni has started catching her own fish in earnest now. Three flounders and a sea bass already this week. It's not just Aeron, Menai and Eitha that are heading towards greater independence.

Notice how Glesni eventually leaves the flounder for her chicks to deal with after some initial aggression from Eitha in this video recorded early yesterday morning. The chicks are already showing an interest in tackling their own food - this tough old flounder was, however, too tough. In both senses of the word.


Fledging

So when will Aeron, Menai and Eitha fledge? They are 45, 44 and 40 days old today, in that order.

We're in the process of completely recalibrating all our stats at the moment. We know exactly when eggs were laid, hatched, chicks fledge, migrate etc. Yet, we only use whole round-numbers of days to express these metrics. From now on, our stats will be accurate to the nearest second.

Here are the fledging ages of all our previous chicks (note days are expressed as decimals):

So, males tend to fledge  younger on average than females by around one day. The stats for the Glaslyn nest are consistent with this as well.

Aeron, being the oldest and the only male, will probably fledge first. He will be 48 days old on Saturday - the traditional starting point of the fledging window. Look out for a fledging competition at the end of the week.

By the way, if you are new to osprey watching, we use the word 'fledge' to describe a bird's first ever controlled flight from its nest. Despite fledging soon, Aeron, Menai and Eitha will be very much with us until the end of August and possibly into September.

And while I'm at it, our young ospreys will not be taught how to fish by their father, mother or anyone else for that matter. Millions of generations before them will have left them a complete "Dummies Guide to Catching Fish". It's all there, in their DNA. They just don't know it yet. The basics are bequeathed, learning and experience will complete the package.

 

The Welsh Picture

We have ten osprey chicks in four Welsh nests this year, that's a productivity rate of 2.5 per nest. This is over twice the national average.

Nine of these ten have been buccal swabbed and the saliva samples sent to Aberystwyth University for our ongoing Welsh osprey DNA research. Look out for a blog about this research in a couple of weeks from our guest blogger, Dr. Helen, a geneticist by trade and a DOP volunteer in her spare time.

Blue 24's egg shell from 2016 - we found enough DNA to include her in the Welsh study

We are still very much in a recovery phase here in Wales in terms of the osprey population. This has a tangible and positive effect on the annual productivity rate of just four nests spread over a large area. When population density is low, productivity tends to be elevated (true for many large bird species) compared to a more normalised population.

Free from the effects of density dependence, competition for food and resources, intruders and all the other stuff that act to suppress productivity, we are still enjoying a chicks-per-nest average of over two fledglings per year since ospreys recolonised Wales in 2004.

Monty keeps an eye on a passing intruding osprey

We're not out of the woods yet though. I well remember watching White YB fledge in 2007 at the Glaslyn - she fell out of the nest rather than fly out. She dangled on a nearby branch for what seemed like an eternity before finally plucking up the courage to get airborne, properly this time, and making it back to the safe confines of the nest before sunset.

We lost Cerist (Clarach's sister) as soon as she fledged in 2013 before a search of the reserve by volunteers flushed her out of the undergrowth two days later. Another happy ending. Ceri, sadly, was not so fortunate last year. Fledging is an extremely dangerous time for any young bird, ospreys included.

 

Privilege


It's an absolute pleasure to turn on the computer right now and tune into the Live Streaming to watch Aeron, Menai and Eitha go about their transformation from chicks to adults. Three beautiful animals getting ready for their big day - we are truly blessed to see them.

Our cameras are the best ever this year, arguably the best in the world. They are funded, as is the Live Streaming each year, by you.

Thank you for allowing us to see the amazing lives of these birds and sharing them with you. Make the most of it, cherish every minute, learn as much as you can, immerse in your emotions, the season will be over before you know it.

Menai - beauty epitomised

 

 

 

Read Emyr MWT's latest blog entries.