Mating
Budgerigars reproduce through cloacal copulation and the two birds rub their cloacas or vents together so that sperm is transferred from the male to the female.
The male persistently courts his mate by tapping her beak with his own to stimulate her. The female eventually lifts her tail in the air, raising her wings a little to let the male know that his stimulation has been successful.
The male balancing on the females back and the entire act usually lasts only a few seconds.