(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.
How do they reproduce? Northern cardinals are monogamous (one male mates with one female). However, they often choose a different mate each breeding season. Northern cardinals begin forming breeding pairs in early spring. The male tries to attract a mate by performing courtship displays that show off his crest and his bright red feathers.