Java sparrows are playful birds that enjoy interacting with a variety of toys. Here is a list of toys that you can provide for your Java sparrow:

1. Ladders and Swings: Java sparrows love to climb and swing, so providing them with ladders and swings can keep them entertained and active.

2. Bells: Bells can be a great source of entertainment for Java sparrows, as they love to ring them and listen to the sound.

3. Wooden and plastic blocks: Java sparrows love to chew and shred things, so providing them with wooden or plastic blocks can give them something to play with and also help to keep their beaks trimmed.

4. Mirrors: Java sparrows enjoy interacting with their reflection, and a mirror can provide them with hours of entertainment.

5. Foraging Toys: Java sparrows love to forage for food, so providing them with foraging toys, such as puzzle feeders, can keep them mentally stimulated and engaged.

6. Rope Toys: Rope toys can be a great source of entertainment for Java sparrows, as they love to climb and swing from them.

7. Shredding Toys: Java sparrows love to chew and shred things, so providing them with toys that they can shred can keep them entertained and also help to keep their beaks trimmed.

8. Bath Toys: Java sparrows love to bathe, so providing them with a small container of water and some toys to play with can be a fun way to entertain and keep them clean.

9. Natural Toys: Java sparrows enjoy playing with natural materials such as twigs, leaves, and small branches. Variety of toys: Java sparrows like variety, so rotating their toys every few days can keep them interested and mentally stimulated.

Java Sparrow chicks, also known as nestlings, are born with a fluffy, pale gray down, which will eventually be replaced by their adult plumage. Both parents take part in feeding the chicks, and they are fed a diet of regurgitated seeds and other soft foods. The chicks will fledge at around 18-20 days old, at which point they will be able to leave the nest and fly.

Java Sparrow chicks are very active and are able to move around and explore their surroundings from a very young age. They are also very curious and enjoy playing with toys and other objects in their environment. They grow quickly and will be fully feathered and independent at around 4-6 weeks of age.

It's important to note that Java Sparrows are not wild birds and are not found in the wild. They are only found as pet birds, and breeding them in captivity requires proper knowledge, care, and facilities. It's important to provide them with a suitable environment and diet, as well as to consult with an avian veterinarian if there are any concerns about their health or breeding.

Also, it's important to keep in mind that adult Java Sparrows have strong territorial behavior and should not be housed together once they reach maturity, as they may become aggressive and start fighting.

The breeding season for Java Sparrows varies depending on the location and climate. In the wild, they typically breed during the rainy season, which is from October to March in their native range of eastern Java and Bali in Indonesia. However, in captivity, they can breed year-round, depending on the conditions provided by the owner.

During the breeding season, the male Java Sparrows will engage in courtship displays to attract a mate. They will puff up their feathers, sing, and perform a dance to impress the females. Once a pair has formed, they will begin building a nest. Both the male and female will take turns building the nest, which is usually a cup-shaped structure made of grass and other plant material, and is usually located in a secluded area.

The female will lay 2-6 eggs, and both parents will take turns incubating them for about 13-14 days. Once the eggs hatch, both parents will help to feed and care for the chicks. The chicks will fledge at about 18-20 days old.

It's worth noting that Java Sparrows are not wild birds and are not found in the wild. They are only found as pet birds, and breeding them in captivity requires proper knowledge, care, and facilities. It's important to provide them with a suitable environment and diet, as well as to consult with an avian veterinarian if there are any concerns about their health or breeding.

Java Sparrows are known for building a cup-shaped nest of grass and other plant material, which is lined with feathers or other soft materials. The nest is usually located in a secluded area, such as a dense bush or tall grass. Both the male and female take turns to build the nest and they will use their beaks and feet to shape and weave the materials together.

Once the nest is completed, the female will lay 2-6 eggs and both parents will take turns incubating them for about 13-14 days. During this time, the parents will remain in the vicinity of the nest to protect the eggs and chicks from predators.

Once the eggs hatch, both parents will help to feed and care for the chicks. The chicks will fledge at about 18-20 days old. Both parents will continue to feed the chicks for a few weeks after they fledge.

It's important to note that Java Sparrows are not wild birds and are not found in the wild. They are only found as pet birds, and breeding them in captivity requires proper knowledge, care, and facilities. It's important to provide them with a suitable environment and diet, as well as to consult with an avian veterinarian if there are any concerns about their health or breeding.