Caiques are capable of breeding after they have reached two years of age. It seems that most pairs begin after they have reached three years. DNA sexing from blood or feathers, or surgical sexing are the best ways to determine the sex of a caique because as a species they are sexually monomorphic and cannot be sexed on plumage, call or size.
NEST BOXES and EGG LAYING
Caiques prefer to roost in a nestbox or log all year round, so it is important to provide them with one. The size of the nest box is not critical, as caiques are not fussy. However for breeding pairs, the entrance diameter should not be larger than necessary. Breeding caiques like an entrance that they can just squeeze into: it makes them feel secure inside the box. An entrance diameter of 6 cm (2.3 inches) is good. The usual clutch size is 4 eggs, which are laid 2-3 days apart from each other. Incubation is done by the female alone and takes approximately 24-27 days depending on how well the female sits and the temperature of the weather.
PROVIDE ADEQUATE FOOD FOR PARENTS REARING CHICKS
The correct diet is important while adults are feeding chicks and should consist of soft fruits and vegetables and may also include an egg and biscuit mix, so that the parents can easily regurgitate food to the chicks. It is recommended feeding caiques both in the morning and evening when young are in the nest to encourage frequent feeding of chicks by the parents. If possible a midday feed is extremely beneficial too. Caiques seem to cope best at raising two chicks only. Some pairs might raise three chicks. I know of one caique owner who's pair of caiques will rear all four chicks. This is the exception rather than the norm. I discussed what he feeds this pair of caiques for them to be able to rear four chicks in the one nest: a mix of kale, spinach and corn kernels combined in a food blender to make a mash, which is fed three times per day at morning midday and evening.
If you have time and experience hand-rearing baby parrots, one option is to take first and second hatched chick for hand-rearing. Caiques are easier to hand-rear when they have already been in the nest for several days, compared to day-old chicks; by the time the third chick hatches, the first chick will be 5-6 days old, and by the time the fourth chick hatches so too will the second chick be around 4-5 days old. So by removing the first chick for hand-rearing when the third hatches, and removing the second chick when the fourth hatches, you won't be trying to hand-rear day-old chicks, but rather chicks that are several days old and already benefited from receiving natural food and bacteria from the parents. The parents can then be left to parent-rear the last two chicks hatched.
Another method is co-parenting. This is where you rotate chicks between hand-rearing and parent-rearing. John McMichael optimised this method with his caiques, and explains it very well in his book Caiques: their care, breeding and some natural history (see this website's page titled Further Reading for more info on this excellent book). Co-parenting has the benefit of the chicks receiving food and socialising from both humans and caiques, which makes for healthy and tame caiques that are well adjusted around both humans and caiques. Co-parented caiques probably make great breeding stock because they are not so afraid around the people yet know they are caiques and have learnt the important skills from their parents.
WEEKLY CHICK DEVELOPMENT
THE FLEDGING STAGE
Chicks fledge at around 70 days of age (10 weeks). During the few days leading up to fledging, the chick will climb to the entrance of the hollow/nest box and spend time looking out into the aviary. Prior to fledging, chicks will lose some weight and this is quite normal for caiques and many species of bird. Actually caique chicks' peak weight is typically around 6 weeks of age and after not much further weight gain occurs. When caique chicks leave the nest, they are not capable of flight straight away, therefore it is best to place extra perches and leafy branches inside the aviary/cage to enable them to climb around without falling to the floor, which could cause injuries.
Two to three days after fledging the chicks will start taking fruit and vegetables from the food bowl when they see their parents eating. This is how they learn to eat independently. At this time it is a good idea to hang fruit and veg such as apple, orange, corn on the cob in the aviary next to the perches, where it will be easy for the chicks to access the food. This encourages them to eat early. During this time the parents will still fee the chicks 2-3 times a day.
After fledging the chicks may return to the nest box each night to roost with the parents. Chicks should stay with their parents for at least 4-6 weeks before they are removed. By this stage chicks should be fully independent when it comes to eating. I have not seen any aggression from the parents towards the chicks when they have been left with the parents for 3-4 months, but be vigilant for any signs of aggression from the parents towards the chicks, which may be a sign that the parents want to nest again, or just want them out of their territory.