What is a parakeet nesting box?

A parakeet nesting box is a box (most commonly made of wood, but also found in cardboard) that parakeet breeders use to replicate a tree cavity where parakeets naturally raise their young. Parakeet (or budgie) nesting boxes should be at least 6" wide x 7" deep x 7" tall (at least), though many breeders recommend wider boxes with the entry hole set off to one side so the parent birds don't crush the eggs when they enter. The entry hole prefered by parakeets in the wild is approximately 1.5" in diameter.