This is Telyn's seventh year on the Dyfi nest, she has laid three eggs every year so far - 21 in total. She's had, to date, two DNHs (did not hatch); one in 2020 and one in 2023.

No osprey that we know of has laid four eggs in a normal clutch in Wales since the species recolonised here 20 years ago. If Telyn was going to emulate her mother, Maya, and plop out a fourth, it would have been laid early this morning. 

Three it is.

🥚 - 1st EGG on 12th April at 08:01
🥚🥚 - 2nd EGG on 15th April at 08:01
🥚🥚🥚 - 3rd EGG on 18th April at 06:05

Here is the chart showing the first mating to first egg timescale. This year it was 12.9 days - very consistent with previous Telyn & Idris years.

Below is a new chart for this year based on the above table. It illustrates the time elapsed from first mating to first egg each year, associated with the respective osprey pairing from 2011 onwards.

Telyn and Idris have shorter periods than when Monty was with us, suggesting (albeit anecdotally from a small sample) the male also influences this first egg timescale. 

The Telyn & Idris pairing has a significantly lower 1st egg time than the Telyn & Monty pairing. Does this mean Telyn becomes more comfortable and assured of the season ahead with Idris than she was with Monty? Maybe she is just more experienced now? Again, the caveat here is that this is a very small data sample size. Interesting though, nonetheless.

Here's a quick clip of Telyn laying her third egg this year, in -1C temperatures:

And here is another brand new chart for this year... it elegantly shows how long a female osprey takes to produce each egg, from egg two onwards (egg 1 is not shown as obviously we don't know when each female flicked on the egg-making switch).

• 73.3 Hours - Egg 2 Average
• 69.5 Hours - Egg 3 Average

So an almost 4-hour shortening in time to produce the third egg vs Egg 2. I guess it would be safe to assume from this, the actual Egg 1 time would be north of 73 hours - possibly 75 or even 76 hours?

*Note: the longer time than usual in 2014 was almost certainly down to interference from another competing female - Blue 24

Delayed Incubation

So you may remember from previous years that Telyn usually employs a delayed incubation strategy. This involves not incubating the first and second egg much (especially at night time) until all three of the eggs are laid. Then, incubation happens as normal.

This delays the clock starting on chick 1 and 2 development, ensuring that the three chicks hatch closer in time five weeks down the road. This strategy decreases the chance of a weaker runt in the clutch, all chicks being more equal in weight/strength.

Three eggs are laid in a span of six days, so everything else being equal we should eggspect a 6-day hatching window. The delayed incubation strategy foreshortens this hatching window - as demonstrated by Nora and Telyn in the chart below.

Note, however, Glesni did not employ a delayed incubation strategy, resulting in her chicks hatching closer to the 6-day laying spread.

The thing is, we think that Telyn has not adopted the same strategy in 2024. She seemed to incubate the first egg immediately - and the second. She's not done this before.

Does this mean we'll get chicks hatching over a longer time span this year? Furthermore, does this mean that individual (versus on a population scale) female ospreys can flip between both reproductive strategies year-to-year based on experience/environment/something else?

Maybe the male has a say in all this? Idris is certainly keen to incubate - as this video demonstrates from last week!

Will be interesting to see. Time will tell.

Splodgology

Every year we have a hard time telling three eggs apart. True, they get slightly smaller in size as each is laid (the third will be around 5-10% smaller than the first), but this is imperceptible by just looking at the whole clutch on the cameras.

So we use pigmentation on the egg shells instead. This is called maculation. Some eggs have a lot, some less. Generally each egg has less than the previous one as the female cannot produce enough pigmentation (usually photoporphyrin) in the three days it takes to produce the second and then third egg.

Thankfully this year, it's quite obvious when we watch the live streaming.

• Egg 1 - Dark horseshoe pattern on one side
• Egg 2 - Disproportionate amount of maculation on one end (the fat end)
• Egg 3 - Paler than the first two for the reasons mentioned above. The last egg is almost always the paler of the clutch.

It doesn't matter to the ospreys of course, which is which, but it does to us. 

It allows us to follow each egg/chick/fledgling/bird throughout its development and, with any luck, its return to the UK to breed years down the line.

Eggspect first hatching this year from 18th May onwards.

Here's Idris' first look at all three eggs last Thursday. Paler egg 3 near his foot, heavy maculated egg 2 on the left and egg 1 with the horseshoe pattern (unseen on this image) top.