Weiro eggs not hatching

Question
Hi Chrys
I have a pair of weiros who hatched out 3 live babies out of 4 eggs. I have left two of the babies in the same cage ( They are about 9 months old now). There are now 8 eggs in the breeding box, the first being laid 4 weeks ago. To date none have hatched and I wondered if this had something to do with the young ones in the same cage. I know the first eggs where laid by the mature birds but I am unsure about the others as I have been on holidays. However the birds do not appear to be spending as much time on the eggs as last time.
Should I now provide another breeding box in case the eggs are from the young ones? Will they share the same box? There are hollow logs available to them but they aren't interested in these for nesting. These are the first birds I have ever hatched out so any assistance would be greatly appreciated. Our weather is warm and temperate throughout the year.

Answer
Hi, Heather.  Thanks for posting!

Sounds like you might have 2 birds laying eggs in the same nesting box OR one female is double-clutching.  Double-clutching is when a female lays one clutch of eggs, stops for a short period of time for some reason, then starts laying again.  Sometimes other birds in the same cage with a breeding pair result in interruptions in the laying cycle.  This is one reason why a breeding pair of birds should be alone in their own breeding cage.  If 2 birds are laying in the same box, both can't incubate eggs at the same time so it could be that neither is incubating these eggs and/or they both could be confused as to who should sit.  If only one bird has laid these eggs, perhaps they just weren't fertile to begin with.  Female parrots can lay infertile eggs without mating with a male, so you might also have the adult female laying fertile eggs and a young female laying infertile eggs.  Also, with tiels, both parents share in the incubation process and both birds feed the babies.  All these birds together could just be thoroughly confused about who's responsible for what!   

Nine months of age is too young to allow the female tiel to lay eggs (it's also too young for a male to have the responsibility of a family).  A female tiel should be at least 18 months to 2 years of age before allowing to mate and lay eggs.  Males are able to fertilize eggs at a younger age, but they need more maturity to care for their family properly.  Also, if the 2 younger birds are related, you should NOT allow them to mate and lay eggs.

No, do not provide an additional nesting box.  My recommendation is to separate the young birds from the adult birds.  If the young birds are mating with each other, you need to separate them from each other also.  Breeding related birds can result in developmental problems for an embryo in the egg...this would be similar to 2 humans whom are related to each other producing offspring.  

Visit my website for more information on parrots in general:

http://www.angelfire.com/falcon/birdinfo/index.html

Please come back with any additional questions.

Chrys