These are photos of a pair of Red-tailed Hawks mating. I've been watching this pair for about two weeks, ever since I discovered their nesting site. A few days ago I was fortunate enough to be on site and in the right place when their brief mating encounter took place. Both birds are using their wings for balance. The male is on top. The female has raised her tail and pulled it to the left. (Her tail is light, showing a reddish tint). In the first photo the male has his tail (dark rectangle) in its usual position as he mounts the female. To transfer sperm, the male also twists his tail to the left ( second photo) to facilitate contact of his cloaca with the female's cloaca. This particular encounter lasted about five seconds. Development of the egg in the female takes about 24 hours. The female will lay one egg per day until she has a complete clutch of one to five eggs. Incubation takes from 28 to 35 days. If the egg has markings, those are deposited on the shell during its passage through the uterus. Rapid movement through the uterus produces streaks of color, slower movement spots. Red-tailed Hawk eggs are white or buffy, marked with buff, brown, or purple.