(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.
Pandas breed once a year. Mating season is from March to May and individual females are in heat from 2 to 7 days. During her heat, a female may mate with several males. After the female's egg has been fertilized, it divides a few times, then it floats free in the uterus for several weeks and does not develop further.