also the weather was slightly warmer than it has been recently so they wouldn't have been using as much energy to keep warm I presume... from all the signs, watery droppings etc and what the vet has said it appears to be some kind of infection.

This is a crop infection caused by the crop not emptying. Have a read here Birds with crop problems - (crop stasis, crop infection, "sour crop") - Talk Budgies Forums

__________________

I've brought him and his friend inside and he seems to be getting a lot better, eating and drinking etc, even though he isn't quite back to his old self he seems to be over the worst of it - thanks for the help. By the way, which month/time is best to put them back outside as obviously they have a lot less room inside.

Leave 'em be until there's no risk of frost.Better less space than ill.The bird could quickly revert if put back in the cold,give it some weeks to build up it's defences again.

__________________

very long time afterwards- but the budgie completely recovered and has been living back outside in the aviary with his friend since May, I was so surprised when he survived I have never seen an animal so ill recover, thank you for the advice. For anyone in a similar situation I would advise bringing the bird inside and bringing in its partner with it otherwise they will pine, in order to heat him back up I put him in the lounge which has a wood burning stove and heated the room with it all day for about three days, and tried to feed him with seed and water from my hands and from going from deaths door where he kept falling off his perch and wouldn't make any sounds within a couple of weeks he was back to his old crazy self and is now happily back outside where he belongs

Thats fantastic. You are lucky to still have it as usually they go down hill really fast.
Do you have any heating in your aviary? Does it have a shed that they can go into or are they out in the open all the time?

__________________
Grandma to Jinja Dog, Mum to Tilly the Cavalier, Tattycat, Moomy, Choo, Sonic, Niven Mc Twisp and Lawna the rabbits and 1 guinea,17 budgies, 4 Cockatiels, 8 Goldfish.

There is no heating inside the aviary, but they have a sort of mini shed that they can go into when they are cold, it is sort of a large wooden box, but despite our best efforts they never use it, so in the winter we put a solid roof on the aviary and cover the sides in see through plastic sheeting to protect them from the wind and they are always fine. I think half the reason why he got ill last time was because a hook on the door came loose in the night and blew open meaning they were exposed to a lot of wind, which I know isnt good for them. In my experience the budgies have no problem acclimatising to cold, the first winter they were out in it was -17C one night and it was the most snow we had in years! we got the aviary from the happy hutch company but they don't appear to sell it anymore.

Hi all,
very nice and amazing animated things,
just take good care of these all !!!!

__________________
nutritionist melbourne

Keep in mind the following considerations:

1, contact with birds, chicks synthesis with antibacterial soap before you wash your hands;

2, each time using a syringe and other utensils should be cleaned and put into sterilized after disinfection cabinet;

3, a container filled with water and food to each cleaning and disinfection;

4, do not become a bird into the nursery, do not want to put into a fledgling bird aviary;

5, the best way to prevent disease management, testing and vaccination. Do not think that the use of toxic chemicals to kill all the dirty environment of the bacteria.