(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.
1 Birds are easily stressed and can die from fear and heat exhaustion if handled excessively or roughly.  If attempting to sex parakeets by their cere colour (the colour of the nostril band at the top of the beak), wait until they are mature (over 12 months old). The cere colour is not helpful for determining parakeet gender in juvenile birds.