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Telyn's Chicks Hatch

Posted: Saturday 2nd June 2018 by Emyr MWT

Telyn is a mother for the first time.

This blog will be work in progress over the weekend, summarising in time-order as things happened.

Friday - June 1st

An osprey's first egg usually hatches at around 37 days. A second egg usually a day less and third a day less again, 35 days (they generally decrease fractionally in size as they are laid).

So by DAY 40, were we worried that we hadn't had a hatching yet? No, not really.

Previous Dyfi incubation times

Telyn had not incubated her first egg 'properly', so we were pretty sure she was a 'delayed incubation' type of girl.

Delayed Incubation vs Standard Incubation

This chart below illustrates two very different reproductive strategies with regard to incubation.

Nora (2011/12) did not incubate the first and second eggs fully until she laid a third. This ensures that if all three chicks hatch, they do so very near to each other in time.

Glesni (2013 - 2017) on the other hand incubated immediately after laying her first egg - this results in a more spread-out hatching sequence.

The comparison is for the three-egg clutch years only, so that we're comparing apples with apples. The average hatch spread for Nora was 2.2 days, whereas the hatch-spread for Glesni's three chicks was more than double, 4.5 days.

Many birds, including raptors, employ a delayed incubation strategy. So why do some female ospreys do it and others don't?

There is clearly no overall advantage to either strategy, otherwise the strategy that results in more chicks surviving would quickly out-compete the less productive strategy into behavioural extinction.


1st June - 18:00

Now we're getting somewhere. We have cracks in both the first two eggs and with the improved professional microphone system this year, we could actually hear the unhatched chicks in the eggs, food soliciting. Absolutely amazing.


1st June - 20:11

Telyn's first ever chick hatches and we caught some brilliant footage of it.

 

As per usual, Monty did his usual trick of immediately brooding his newly hatched chick. At the same time Telyn was experiencing her chick feeding and brooding instinct for the very first time - so what did she do?

She lay down right next to Monty, parallel to him, and copied him.

Synchronised brooding; if you can't beat them, join them

Allis Shad

Monty thought so much of his first offspring with his new partner, that he brought in a speciality fish - an Allis shad (Alosa alosa).

These are members of the herring family but are usually found much further down the western Atlantic coast of Europe and Africa. So this individual was right on the northern edge of the allis shad's natural distribution.

Allis Shad

Monty has caught one other allis shad that we've recorded over the last 10 seasons and a couple of the closely related twaite shad too, which has a similar Mediterranean-based distribution. Global warming or just fish on the outer edge of their range?

 

2nd June

Just 14 hours later than the first chick hatched, the second did. But this guy was from the first egg laid - exactly the same scenario as Einion and Dulas way back in 2011. A common consequence of a delayed incubation strategy is eggs hatching either simultaneously or out of chronological order.

A second chick from the first egg laid

We were a bit worried about the second chick for a while, he seemed very unresponsive and by late afternoon he looked for all the world that he had died. We zoomed all the cameras in but we could detect no movement, no breathing.

The next time his mother got up, however, he had magically found an inner-strength and was bobbling around again. Shortly afterwards he consumed his first ever meal.

Bobby Two - Back from the dead

3rd June - 11:24

So by early Sunday morning the crack that was developing in the third egg 24-hours previously was getting larger and soon we could see a hole appearing with a tiny egg-tooth chipping its way out.

Pip, pip - anybody out there?

So Telyn, on her first full breeding attempt, has managed to lay three eggs, incubate them to perfection and seen all three hatch successfully. Not bad for a novice.

Her delayed incubation strategy has worked out brilliantly. Despite six whole days between laying her first and third eggs, all three have hatched within 1.6 days of each other; a shortening of the laying span of 73%


1st June: First chick hatches at 20:11

2nd June: Second chick hatches at 10:06

3rd June: Third chick hatches at 11:24

 

And Finally

I don't want to get too bogged down with stats and charts here, but if you allow me just one more.

Nora and her niece Telyn both employed a delayed incubation strategy. Glesni, also one of Nora's nieces, adopted a more conventional incubation strategy - i.e. start incubating straight away.

Hatching spans of all the Dyfi three-chick broods 2011- 2018

Two quite different reproductive strategies, both having the same successful end result.

As we mourned the passing of Nora and then Glesni just a few weeks ago, Telyn has very much reminded us that life goes on. For a life to flourish another life has to give way.

The weather is set perfect for the next week or so, Telyn's three youngsters have the best start in life that they could wish for.

Many thanks for all your messages and support over the last few days in what has been a very trying time with some of our Live Streaming issues. And thanks also to all our Protection volunteers who can now stand down again for another 10 months. Your 40 days and 40 nights' work have been richly rewarded.

A hat-trick at the first time of asking. What a bird, what a weekend, what joy.


 

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