(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.
At around one year of age, the cere, or pink fleshy nostril band above the beak, changes color in parakeets. This is normal and expected. In female parakeets, it changes to tan, pale blue, white or brown. In males, it changes to a bright, vivid blue, except for a few color varieties in which it changes to bright purple or remains pink. This color change helps to easily tell the difference between mature males and females.