The 16th day after incubation started and 4 eggs still remain.

Generally Blue Tit eggs take between 13 and 16 days to hatch, so it is probably best to assume that four may fail ... even if they do hatch now, the age and size difference between the chicks may lead to them not getting enough food as blind open beaks compete for food.

Why this should possibly happen is a mystery, and there must a whole host of possible causes.

After having closely watched the female incubate the only thing she appeared to do differently to females in previous seasons was always leave the eggs uncovered when she left the nest. Did they get too cold? The weather wasn't that bad.

There is another possible theory, and that it that the nest is not deep enough to retain heat from the bottom of the nest upwards.

The floor area of the box is slightly larger than before, and whilst this 'may' have allowed more room for the two to roost, it might also mean that she thought enough nesting material had been brought in, but in reality it just isn't quite deep enough.

Fingers are still crossed of course, and given that one hatched today, we could still see the others come through.

Egg Number 4
A late fourth egg hatched at 9.33am. Mum was again sitting in the nest cup (complete with a white feather stuck to the end of her tail) when suddenly she moved upwards and was seen to have a small white item in her beak.

Seconds later and half an egg shell was being eaten:

During the shell feast, a rather confused male arrived with food. He really didn't know what to do, as he looked through the window and saw the female chomping on the shell:

After consuming the first half, she immediately started on the second and when finished, it was head down and white tipped tail in the air for a check:

Back for another go, the male successfully entered and fed his mate, and in turn she fed a chick:

Mum didn't stay around for very long after the arrival, and popped out for a break.

Being the perfect father, the male brought food and offered it around, but something else was going on outside ...

Whilst he had his head over the nest cup, another foreign Blue Tit was at the hole looking in! It looked similar to a rather rough looking bird that was spotted showing interest 6 or 7 weeks ago:

Why he didn't notice or even react to the situation is surprising, but at least it didn't enter, avoiding possible trouble in the process.

Egg number four has hatched and mum eats the shell whilst a confused male hangs outside.

Here are a few observations from the day:

A Joke Meal
The male didn't quite get it right with a feed this morning, or maybe he was just having a joke with the other half?

In he comes with a nice full beak of food, offers it to the female, only to quickly whip it away again before she could take it. She did look a little stunned and just sat back in the cup pondering:

The male plays games.

What Goes In, Must Come Out
It's that time of the season when we have to deal with toilet duties, so let's get it out of the way now ...

Here we see the male bring in a small food offering and one of the chicks gratefully accepts. More and more feeds are going this way, and a parent will often hang around for a few seconds to see if anything needs to be removed from the box.

Sure enough, the chicks upends itself after eating and produces a faecal sac. Usually these get removed from the nest and are deposited somewhere in the garden.

... Not this time though ... the male eats it:

The male is fed by a chick ... here.

Mum can try and Squash You!
It's amazing how much the older chicks have grown in just a few days.

'Chick Popping' has started, and you have to be careful if you stick your head up when mum is attending to the nest.

This will be fun to watch in a few more days as they get bigger.

It can sometimes look rough on a little one, but it happens every year, so they must be fine!

Help, i'm getting squashed (but she does tuck it back under afterwards).

So four left and we wait to see if any late comers will join the family:

Every day a snapshot of the chicks and their development is posted in the Summary section of the site, so you can see just how quickly they will develop.