Today marks the 100th day of coverage on Nest Watch since we started watching the box back in January, and rather aptly the female has waited until today to produce her first egg !

Things began to change last night and by 9.00pm we were left with no doubts in our mind that today was going to be the day.

From now on it looks like life for the pair will be different, and for the first time since the 13th March the male didn't share the box with his partner.

And just as a reminder, here he is on that first night inside the box:

On his second night he had chosen what became his favourite corner:

You can see him settle down again here.

On the 28th March he enticed the female inside and since then the pair had been inseparable:

So what changed last night?

She spent far longer than of late sitting in the nest cup tugging away at nesting material as she re-arranged and sorted things out. It was as if she was making the final adjustments to the space where she lays her eggs.

Also, she was very restless throughout the night. Looking through the camera logs they show that movement was detected on average 11 times every hour.

A big change is obviously the fact that the male didn't share the box with her, and what is really interesting is the fact that he didn't even try to enter. He looked through the hole, but didn't ever actually poke a beak through it.

From 7.30pm until 8.23pm he made five visits to the outside whilst she was already inside. The first saw him with food, but he didn't venture inside and offer it to her:

The four further visits saw him briefly visit each time, probably no longer than 4 to 6 seconds and the last three were within 2 minutes of each other.

On every occasion he was silent, and she didn't acknowledge his presence. There were no chirps as he has so often made to announce his arrival over the past weeks:

How did he know what was about to take place?

It's something we can't answer, and only nature and the Blue Tits hold the secret ... maybe they had a family planning meeting during those long breaks yesterday?

We do wonder where in the garden he now sleeps, and during the weeks to follow as more eggs are laid, incubation passes and the offspring raised to hopeful fledging.

But before we get to that stage, the eggs have to be laid. And of course the great news today is that the first arrived.

Whilst she was restless during the night, she really started to move around the nest cup from 5.40am onwards. She started turning around and getting her head down into the depression:

She's preparing her nest here.

The preparations continued up until 5.57am when she stopped fidgeting and became still in the nest cup. It looked as if her breathing was beginning to increase as the final minutes passed before egg labour was to take place:

Still motionless, and with her eyes looking quite open and transfixed a clicking sound was heard at 20 seconds past 6 o'clock:

Clicking sounds are important, and a good indication as to when actual labour is taking place.

By 35 seconds past 6 o'clock the frequency of the clicks had increased.

A further 30 seconds passed, with ever more clicks being heard and by 06:01:15am her beak was opening and closing in time with them.

She moved slightly lower into the cup, and her body was by now also moving up and down as she went through the final motions of pushing the egg out. The clicks had stopped, and as yet an unseen egg was now lying in the nest:

By 6.02am it could be seen that her breathing was possibly still a little high, as she still continued to sit motionless, resting herself after the ordeal.

At 06.02.18am her head moved noticeably sideways as she made her first proper movement since labour began. Thirty seconds later and she was looking a lot more relaxed about the whole affair:

Her first egg labour can be seen here - it's a 4.5 minute video which shows her going through the motions from 05.58.30am to 06.02.50am. You may have to turn your speaker volume up to hear the clicks, and keep an eye on the clock at the top right-hand corner of the picture. The first click can be heard at 20 seconds past 6 o'clock - poor thing, it looked like hard work in places and somewhat concentrated the mind.

She remained in the cup for just over a minute and then hopped out, but she wasn't going to let the camera know what was in there:

And thirty seconds after that, and later than we would have thought, she poked her head downwards to check what she had just put so much hard energy into producing:

A few more minutes were spent with head down and tail up - you can never do enough housework or checking sometimes:

As she continued with her work, the male could be heard calling outside. Suddenly realising that a hard earned breakfast was on its way, she leapt out and moved to the far corner.

Food didn't instantly arrive, so it was back to the warm spot and she gave out a few approving chirps to encourage him.

Bingo! The male arrived through the hole and breakfast was served:

We mentioned a few days ago when she received a feed on the outside of the box about her flapping and vibrating her wings. She hasn't been seen doing it again since, but now she will start to display this sort of behaviour far more often.

The male will have to work hard at times, because when he arrives with food, she stays put. He has to bring the food to her, she's not minded to move towards him!

The male arrives and serves a celebratory breakfast here. (Apologies for the early morning aircraft noise).

Blue Tits are notoriously secretive about their eggs, and will more often than not cover them over. At 6.13am she moved out of the cup and revealed what might be an egg, but was probably more likely a feather:

Three minutes later and she bounced around the side of the nest, looked out and left:

The day returned to normal, with a not so observant male arriving with second helpings 10 minutes later. Again he looked confused not to find her home, and once he had gone back outside and still couldn't see her, enjoyed the meal for himself:

A precious egg needs to be covered up, and the nest is never quite as it should be. Between 7.00am and 8.20am six more deliveries arrived - just to make sure:

She didn't return again until 1.10pm with a few more strands and throughout those hours the male kept missing the wife:

He looking good though, and if this chap continues with those food offerings, the female and the chicks should be well provided for.

Amazingly enough by 5.30pm at the time of uploading this entry she hasn't been back inside the box again. The male has of course visited the front on many occasions, especially between 4.00pm and 5.00pm. He's been very chirpy when he arrives, if not lost and confused when he leaves:

A great day, and one that heralds the next stage in their development this season.

We always have questions, and the next one is of course is how many eggs will she lay? In 2005 six eggs were laid, and last year ten. Happily all hatched and fledged.

Over the coming days each morning will be greeted with anticipation, although an egg a day may not always happen. Sometimes female Blue Tits can skip a day.