Cage is a major factor in a bird’s life, it is their home and very dear to them, we should have a proper size and type bird care for different species, this is what I believe for my parrots and they are very happy.
Safety
As with bar spacing. your bird head, wings, feet or beak may get caught in the cage beware of doors, fatches and other cage parts that could trap your bird. Lead and zinc content in cages has also been a problem, especially older or painted cages, Galvanized wire contains zinc and should be avoided. Also watch for sharp edges on cage parts.
Cage Size and Bar Spacing
Budgies 18 18 – 1/2” spacing
Lovebirds 18×18 – 1/2” to 5/8” spacing
Cockatiel 22 × 17cage – 1/2” inch to 5/8” spacing
Conure 24 × 22 cage – 5/8” to ¾” spacing
Caique 24 × 22 cage – 5/8” to ¾” spacing
Amazons 32 23 cage – 5/8 “ 1” bar spacing 4mm bars
African Grey 32 23 cage – 5/8” 1” bar spacing 4mm bars
Smaller Cockatoos 32 ×23 cage – 5/8” 1” bar spacing 5mm bars
Larger Cockatoos 36 24 cage – 1 inch bar space 5mm bars
Macaw 36 24 cage – 1 inch bar space 5mm bars
Cages Shape
Avoid cylindrical cages as they tend to be too small some birds feel insecure in cylindrical cages. Cage should have so much space they can get most of their exercise flying within the cage. Large parrots, taller cages are fine since the extra height does provide exercise by climbing although they still need to be wide to allow stretching and room to play.
Quality
Invest in a good cage which are made by high quality materials but they are expensive though I prefer to buy these cages for my parrots they are safer and will be worth it over the lifespan of your parrot
Easy to Maintain
You should buy cages that are easy to keep clean. Look for a pull out tray to clean the cage. Food and water dishes that can be easily removed and replaced without opening the main door of the cage.