Budgerigars prefer as much room to exercise as possible. Available space will dictate the size of the breeding cage.
Commercially manufactured Breeding Cages range between 12 inches height x 18 inches wide to 18 inches height x 36 inches wide. Depth being approximately 12 to 16 inches.
Experience shows that the larger the breeding cage the more successful the clutches.
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You can also click here for more information Nesting Box Information