(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.
Among timber rattlesnakes, courtship and mating occur either in the spring or in late summer. A male timber rattlesnake courts a willing female with a special three-step dance.. First he moves alongside and on top of the female. Then he starts rubbing his head and body against hers with jerky movements. Finally, he curls his tail under the female's, and mating takes place.