I was wondering about spaying and neutering.
Any more details on their breeding season?
I'm not an avian vet, nor do I play one on the internet. That being said...
Birds can't really be easily spayed or neutered because of their anatomy. As you probably are aware, they're 'goods' are internal and as a result major surgery is required to remove them. It's my understanding that this is particularly difficult in hens.
As a result, it's easier to work around the hormones than to try to mitigate their influence through surgery.
Breeding season depends upon the bird. But, in general, the hormones start to kick in as the days get longer. Most parrot owners try to make sure their bird gets at least 10-12 hours of darkness every day as this seems to be the best way to control their hormones.
For more information, I'd suggest any of the execellent bird boards out there. I like the My Toos site as well as Pretty Parrots and For the Birds