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Recap: Spring 2019

Posted: Sunday 2nd June 2019 by Thom

MWT 3 ChicksThree Chicks 2019 MWT

Well there we have it, the most anticipated, worrying, exciting, anxiety inducing annual event is over, and without a hitch. As we all know we have three new additions to our osprey family and Telyn is proving to be a fantastic parent, and it’s only her second year! We have also learnt a lot over the last few weeks so here is a recap of the key events that defined the early 2019 at DOP.


 

We managed to get some confirmation of something we suspected Telyn might have been doing from last year. Like last year, just after laying her first egg she seemed a little unwilling to incubate for extended periods of time until the second egg was laid. 

Why could this be?

Egg 1 was periodically left in the cold to halt development 

 

It was suspected last year that Telyn was displaying a behaviour seen in other birds of prey called “delayed incubation”. What this does is theoretically closes the gap between each egg hatching, theoretically reducing the chance of there being a big chick in the nest that gets a disproportionate share of the fish. Evening out the odds as it were.


But would this have an effect? We would have to wait over a month to find out.

Family potrait

The egg laying dates were as follows,

Egg 1: 6.20am on the 17th of April

Egg 2: 5.59am on the 20th April

Egg 3: 4.41 am on the 23rd April

26th April: Storm Hannah

 


Storm Hannah struck in the night, right in the middle of the incubation period, with rain and gusts reaching a high of 60mph. 


Osprey choose to nest exposed to the elements, so they can spot intruding Ospreys in their territory and to keep an eye out for predators. However this also meant Telyn was exposed to the worst the storm had to offer.

Telyn ducking down out of the worst of it 

 

But she dug in, sat tight trusting in her waterproof feathers to keep her safe and dry (probably asking herself “why on earth did I leave Africa”).


The next morning, we went down to the observatory relieved Telyn and her nest were still there, seemingly untouched the chaos of the night before. We were not so lucky with the storm having thrown trees onto our visitors centre, and crashed our livestream!

Monty Incubation

 

Monty did his fair share of incubation over the spring, slightly up from last year at 16.7% (Compared to a previous of 16.05% in 2016 and 15.27% in 2017).

This was calculated from data collected by live stream viewers and collected by Pamela, so a huge thank you to you all.

 

26th May: Hatch day!

 

The day finally arrived heralded by a small crack in egg 1. We had suspected something was about to happen hours beforehand. Telyn was often fidgety, often appearing to listen intently to the eggs and even at one point attempting to feed Monty some fish as if he were a chick.


As Telyn could hear a chick, her instincts were telling her to feed it. But only Monty was present. This is known as a “Fixed Action Pattern”.


Our theory was again confirmed this year with chick 1 and chick 2 hatching within 8 hours of each other. The result was clear to see, the size difference between the two were far less pronounced than usual. Chick 3 however hatched two whole days after chick 2 on the 29th, and is noticeably 17th April: Egg 1 Laid

Crack in egg 1!

 

Does this mean Bobby Bach will fare worse than his or her siblings? Most probably not, as I will explain later.

24th May: Crow Bashing

Corvids pose the biggest threat (other than humans) to the survival of ospreys in the UK. So much so that they have their own warning call that ospreys only use when a crow is sighted.


Luckily Monty is well versed in “crow bashing” and certainly adds a bit of excitement to the day of visitors and colleagues down in the visitors centre.

 

29th May: First feed for all three chicks

For the first time everyone was present at meal time for 6:40 in the morning. All enjoyed Mullet for breakfast and with all the chicks present we could get an idea of some family dynamics. 

Bobies bach 3

 

As expected with Bobby Bach being the smallest, we was often being fed last and understandably this brings up a lot of concerns. After all we’ve all seen footage on shows like Springwatch where the smallest barn owllets get eaten by their bigger siblings, or golden eagle chicks bullying each other to death. Is there a chance this could happen in our nest?


In short the answer is NO

So why are osprey different? And why do other raptors have such high levels of siblicide?

The variety of fish caught by Monty 2018

 

One big difference is diet. Fish stocks in the dyfi are robust and more reliable than the voles and rabbits that other British birds of prey rely on. Rabbits and vole populations follow cycles of rises and crashes. Bountiful prey and then the following year almost nothing. While Ospreys hunt a variety of fish, in various habitats and usually find enough food for 3 chicks to survive.

The benefits of a broad fishy diet.

This is one reason why some species like kestrels and owls have larger broods.

In peak prey years six or more owl chicks may fledge, making the gamble worthwhile. Osprey on the other hand, except in really exceptional years, rarely fledge more than three making them in evolution terms losers.

But Osprey become the winners in years where vole populations crash when owls or Kestrels can struggle to fledge even a single chick. 

Kestrel have far more chicks than ospreys do (Source Sussex Wildlife Trust)

 

So why do other birds of prey utalise such violent development stratergies?

Well the presence of smaller chicks that loose out in the competition for food can paradoxically also beneficial (in evolutionary terms). If there were two chicks competing for limited food resources equally, then both chicks will have to split meagre rations threatening the health of both. But having one chick that is destined to lose out in the fight for food means the bigger chick most likely to survive, will be sure to get enough food for at least one successful fledging and that way the genes will live on.


Genes can be really really selfish.


Luckily for Bobby Bach, in a recovering population, with little competition from other nests in the area and plenty of prey to choose from, evolution has calculated that 3 is the ideal number of eggs for this species.


This is a fascinating subject and has been covered in more detail by Emyr in this blog - right here

The hatching dates were as follows,

Chick 1: 8.58pm on the 26th of May

Chick 2: 4.02am on the 27th of May 

Chick 3: 5.37 am on the 24th of May


1st June: First Sea Bass


Monty decided to mix things up a bit last Saturday and bring home the first bass we have seen so far in 2019. The fish is known as draenogyn here in wales, named after the welsh word for hedgehog due to having a spiny dorsal fin.

Monty and a huge bass

 

These fish have had a hard time nationally, is this a sign that local fishing restrictions are starting to take effect?

 


 

So we have every reason to believe that this is set to be another successful year for osprey on the Dyfi, and why shouldn’t it be. Especially when you couldn’t ask for better parents than these.
 

Two very proud parents 

 

 



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