Start with occupants
Record species, adult count, breeding state and expected fledglings for every enclosure. Length, depth and height all matter, but perch placement and equipment can consume the usable volume. A common cage size in a bird room is not evidence that it suits every species.
Leave clear routes
Place stable perches so birds can fly between them without hitting dishes, branches or the nest. Allow tail and wing clearance. Use a quiet retreat without filling the whole flight with cover. Food and water should be accessible and protected from falling droppings; Pin-tailed Parrotfinches particularly warrant elevated stations.
Plan the next stage
A pair's cage can become crowded as soon as a clutch fledges. Prepare grow-out housing before laying, and keep a safe separation option for aggression or illness. Position cages away from direct AC flow and rapid local temperature changes. A purifier can be part of room management, but cage hygiene and ventilation remain separate jobs.