(of an organism or tissue) living in the absence of air or free oxygen. pertaining to or caused by the absence of oxygen.
Parakeets can breed year round if conditions are right in their environment. Normal breeding season begins early in the year and continues until fall. It is very rare to see parakeets mating, but a male and a female must mate to keep the eggs fertile.
However, budgerigars (parakeets or budgies) are determinate layers and often lay just 4, 6 or rarely 8 eggs to complete the clutch. Amazons, in particular, have an intense hormonal surge in the springtime, and often exhibit extreme behavioral changes at that time.