How do Ospreys reproduce? Before Ospreys are able to conceive the female must pick her mate. To do so males put on a show referred to as "the fish dance" or "sky dance". This dance cronstructs of briefly treading air, droping down a hundred feet, before treading air again and then quickly rising. If the dance is done well the pair mates quickly. "Ospreys are believed to be largely monogamous, and strongly faithful both to nest and mate."{1} Before mating the Osprey must build a nest, or home where the offspring will live in their early years. To do so, they pick a location, usually all the top of a tree or cliff side, and begin gathering materials used for construction. Ospreys tend to stick to the same area for years on end. "It takes both birds 14-21 days to complete a new nest, which at completion can be 120-150 cm across and 50-60 cm deep. "{1} "In the second half of April, the female lays two or three eggs at 1-3 day intervals and incubates them for 37 days per egg."{1} If there is not a lot of food only the oldest bird will survive. Ospreys divide the responsibilities of raising their children equally between the pair. The female does most of the direct feeding and protecting and the male provides fish for both his mate and the children. "After fledging at c. 53 days, both parents provide food for the young, which stay close to the nest for a further two months."{1} Many Ospreys die young before they mature at age three. The ones that do grow old usually grow to live till around eight years. the oldest known Osprey grew to be 32. "Most birds do not have the same reproductive body parts as mammals. Instead, both male and female birds have a cloaca – one opening (also called the vent) that serves as the bodily exit for their digestive, urinary and reproductive systems."{2} The same place where eggs are laid also is where the bird pees out of. During the year the bird's private parts are hidden inside of it. When it is mating season however (spring), the bird's cloaca swell, coming out of the body slightly. When it comes time for mating male testes swell producing sperm and female ovaries swell making ova. Males store sperm untill there is a mating opertunity where it can be incerted into the female's cloaca where it travels to fertalize the ova. "Excited by their hormones for a week or more and will mate several times during that period to increase the chances of successful insemination."{2}