The series of bodily changes that occur in the female of most mammals from one period of estrus to another. The estrous cycle usually takes place during a specific period known as the breeding season, which ensures that the young are born at a time when the chance of survival is greatest.
ear-to-ear. It's about smiling. Ear-to-ear smile or grin is when you have a very broad and generous smile. Such a smile when each corner of your mouth is by each of your ears. Explain to me why you don't have an ear-to-ear grin right now.
(The ear tufts of some owls, such as the great horned and long-eared owls, have nothing to do with hearing.) The facial disk itself serves to focus sound waves into the ears. Strangely, the ear opening on the right is higher than the one on the left, allowing each ear to receive sound from a slightly different angle.