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Clarach and Cerist Fledge

Posted: Sunday 25th August 2013 by Emyr MWT

Dyfi Osprey Cerist leg ringDyfi Osprey Cerist leg ring

 

Both sisters have fledged this week. Clarach (2R) flew for the first time last Sunday, August 18th and Cerist (1R) went two days later. They were both 51 days old when they fledged, pretty young for ospreys, especially females.

Of all the ospreys that we know of and have data for in Wales, Clarach and Cerist are the youngest females to fledge. In fact, they went earlier than most male ospreys who, on average, fledge a day or two earlier.

Clarach and Cerist (extreme right). Females in red and males in blue
Welsh Osprey fledging data
(NB. Ceulan - 3C, fledged at 53 days last year)

So why did these two sisters fledge so early? It seems clear that there was a low level of disturbance just prior to both girls going, Glesni was up in the air alarm calling on both occasions. The thanatosis behaviour (playing dead) that had served them so well for most of their lives to date was suddenly redundant. Clarach, and Cerist two days later, deciding instead that flight was now the best option rather than hide.

Clarach's inaugural flight was a short one, just over two minutes and little more than the Wright brother's first powered flight a century and a bit prior. Unlike Orville's maiden flight however, Clarach landed back at exactly the same spot as she took off from, the nest. Her flight time was two minutes 13 seconds.

Clarach didn't take to the air again that day, deciding that the sanctuary of the nest was the best place for her. She did fly again the following day (Monday) however, and this time she saw Monty's second nest from a totally different angle. She must have liked it, she landed in it.

Clarach visits Dad in his shed and is greeted by a thousand flies
Dyfi Osprey Monty and Clarach in the shed

Clarach's aeronautical skills improved very quickly over the next few days and now, exactly a week on from her first test flight, take-offs and landings are a breeze. She's even managed to use two airfields in a week!

Dyfi Osprey Cerist

Cerist's first flight was altogether a different matter. Take off was pretty standard, a 09:06 departure on Tuesday morning. The problem was the destination.

We saw her for around a minute after take off and then she disappeared. We have no idea how long she flew for, how far or where she landed. She didn't return all day on Tuesday, but there was no need to worry, it's quite common for youngsters to fledge and not return to the nest in the same day.

Clarach home alone for the first time.
Dyfi Osprey Clarach

The following morning she was still not back, nor did she return throughout the day. By Wednesday evening we were proper worried. Yes, there are plenty of examples of ospreys returning to the nest several days after fledging sometimes, but we knew that young fledglings tend to stay on the ground and we were right in the middle of the highest tides of the year. If she was stranded on the ground somewhere, even in dense vegetation and relatively safe from ground predators, there was a possibility that she may drown.

On the Thursday morning, now two days after Cerist flew for the first time and vanished, we quickly arranged a search party. We know that young ospreys are not fed by their parents whilst on the ground, nor had we seen any evidence of either Monty or Glesni doing so. Thursday was the right time to go, before starvation would set in and just before the highest of the tides. We would invariably disturb the remaining three ospreys as well, so we couldn't search while Clarach was still finding her wings earlier in the week. We could have caused a whole new set of problems by trying to fix another one.

(A huge thanks to Vanessa Greene here. Vanessa has been studying ospreys in Minnesota for 20 years and has seen ospreys fledge to the ground many times in those two decades. Vanessa communicated with us her experiences, and what she explained to us formed part of our decision making process. You can read Vanessa's short blog on osprey fledging here that she posted at the start of the month - before Cerist went missing. Many thanks to you.)

17 smiling and clean volunteers congregate at DOP for a comms meeting at 10am. They weren't smiling, nor clean for long.
Dyfi Osprey search volunteers

We started off at the very top of the reserve and worked our way methodically in a westerly direction towards the osprey nest. We knew that there was a good chance that if Cerist was still alive, she would probably be not too far from the nest, despite the parents not giving her location away.

The three DOP staff, Janine, Alwyn and myself had walkie-talkies, so that we could communicate effectively with each other and the vounteers in the thick vegetation. To say it was heavy going is an understatement! The heat didn't help either, nor did the midges.

Dyfi Osprey Search party

By around 13:00 we were approaching the nest when Alwyn called up on the radio "Osprey just taken off from the ground". Well that sounded promising, we were expecting a young osprey to stay still and hide however, particularly as Monty and Glesni were by this time in the air and alarm calling. Nevertheless, the osprey had been flushed from the ground along with 25 lapwings, some curlew and the mandatory flock of snipe. The osprey flew away from us (obviously) towards Dyfi Junction train station.

By 14:00 we were all back at DOP. Monty and Glesni were around, as was a young osprey high on the Dyfi Junction mast, but no sign of Cerist on the nest still. We've seen Leri, Einion, Dulas and Ceulan perch here in the past so it was nothing new - it had to be Clarach we thought.

After a quick drink and sandwich we split the search party into three groups to search the southern part of Cors Dyfi in the afternoon. We all went our separate ways and around half an hour into the search there was an almighty scream coming over the radio. Maria was back at base and monitoring the cameras for us, and the radio communications..

"1R, CERIST - BACK ON NEST - CERIST - 1R - NEST - SHE'S BACK - CERIST - 1R - NEST"

We got the message. After 54 hours away from the nest, Cerist had returned.

One of the three search teams was searching quite close to the Dyfi mast and although they didn't see the osprey, they must have disturbed her enough to fly off.

A quick check of the leg ring was all Maria needed to send her, 17 volunteers and a visitor centre and hide full of people, absolutely berserk.

1R, Cerist, welcome back.
Dyfi Osprey Cerist 1R

So here's a video of both Clarach and Cerist fledging this week, including that emotional return of 1R

I must admit, I had no great expectations of finding Cerist over two days after she fledged in some pretty inhospitable terrain, prone to flooding. It was a bit like trying to find a needle in a haystack, only that you didn't know where the haystack was. It would have been a pretty long winter of soul searching however if we hadn't have tried. A pile of "what-if's" that you really don't need on your conscience to battle with, having lost 50% of this year's offspring in circumstances unknown.

Would Cerist have made it back to the nest if she hadn't have been flushed off the ground just 300 metres from the nest? Probably, possibly, nobody cares or gives a monkeys. She's back and that all that matters.
 


Just a quick behavioural thing before we open the fruit juice. When ospreys return to the nest like this several days after leaving, observers often report some aggressive behaviours by the parents towards the long-lost child. It happened with Blue 44 last year at Loch of the Lowes, it happened at Rutland also in 2012 and has occurred at other nest sites. Lake District ospreys in 2005 springs to mind.

Guess what? It happened here at the Dyfi too. A few minutes after returning to the upstairs nest and having been joined by her food soliciting mother, Cerist suddenly came under attack from Glesni. Nothing too vicious, just three aerial dive-bomb type manoeuvres before calm was restored.

Have a look here:

So what's all that about? Did Glesni see Cerist as a threat? Did she recognise her initially?

It is probably a behavioural response to a low level distress event. An offspring returning after 2½ days away, having not being fed by Glesni, food calling like crazy, looking bedraggled and ruffled, train approaching. All these events combined would have triggered some sort of distress related behaviour in Glesni, and a common reaction to a stress event is aggression. In simple terms, if you're not comfortable with something and it's something that you've not seen before or is alien to you - chose aggression as your first behavioural response. Next time the stressful event could be more serious and aggression could save your life.

It is in the bird's interest to chose aggression as the default setting when faced with uncertainty. They do it all the time. What it is not however, is a "telling-off"!!

So it's happy families again, the sun is out, and it's August Bank Holiday here in the UK. Enjoy it and the ospreys, they will soon be gone for another season.

 
Clarach wondering what all the fuss is about
Dyfi Osprey Clarach 2R
 

A very special thanks from Montgomeryshire Wildlife Trust to all those at DOP on Thursday, the camera operator the search team and all the volunteers that manned the project whilst the staff were out looking. A phenomenal result by genuinely caring people. Team work at it's best.

 

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