Death in the box

[prebendal]

In the camera box this year we were delighted to have blue tits as opposed to our previous great tit residents.
10 eggs, difficult to count the chicks on hatching but at least 8 if not all 10. At 4 - 5 days old the chicks lost the will to live and after a few hours all was still in the box despite parent birds attempts to feed.
I appreciate the loss rate is high but can anybody throw light on the cause.
The previous evening and night we had over 1" of rain, it felt cold but temps didn't drop below 11' C.
Last year we had a similar experience with the Great tits, they lasted a few more days.
Previous 3 yrs most fledged.
Possible causes: cold? wet? parasites? (each year we remove the nest from the box but no thorough cleaning) lack of food? ( box situated in large garden adjacent to farm yard) Poison? (Rat bait, used round farm but in bird proof stations).
Any ideas gratefully received.
Despite the deaths in the last 2 years, these boxes with cameras have given us much compulsive tv viewing and in my opinion should be compulsory in every house/ school. I wouldn't even begrudge my MP claiming for one on their expenses.

[PiratesAhoy!]

Difficult to say. Could well have been difficulty to find enough suitable food. Weather can play a big part in what sort of natural foods are available to small birds - as youngsters they're insectivores - the parents need to find small insects, larvae and aphids to feed them. If there's a lot of rain, it can make those natural foods difficult to find.

If the parents were first-timers, they just may not have got it right.

Also parasites, diseases could be a possibility.

If you don't already, consider providing additional food for the tits during spring. If they have more food for themselves and therefore energy, they'll be better able to hunt for food for their young.

[Jandy]

A regular supply of mini mealworms would be a great help to the parents, with spring (and therefore the supply of natural food such as caterpillars) coming ever earlier. Of course, as you say, there could be many other reasons. It would be a good idea before next year's nesting season, to make sure the box is thoroughly sterilised from any pests/parasites using a bird-friendly product.