After mating, the female lays between one and three eggs and she does most of the brooding. The male feeds her, roosts nearby to protect her, and takes a turn on the nest now and then while she goes out to hunt for herself. If it is very hot, she may fly along the surface and dip her breast and legs into the water, then return to the nest and wet down her chicks to cool them.
After the eggs hatch, the female still stays with the chicks most of the time for about 30 days, shading them from sun or rain and hail. The male feeds his whole family. She tears fish into smaller pieces and feeds the chicks. When they are bigger, have grown their brown feathers and can eat pieces by themselves, she may help her mate with fishing. Young are fed until they have learned to fly and to fish for themselves.
Osprey migrate in September-October to Central or South America. Adults will return in March or April, but the young birds will stay in the south for the entire year plus the following winter before they return to the general area where they fledged. In their third year, they are mature and may attempt to breed, but often not successfully. Less than 50% of the young birds that fledge, survive to return in their third year. After that the mortality rate decreases and the life span of adults is somewhere between 10 and 20 years.
As a volunteer, I also was trained to use the radio telemetry equipment that would be necessary to keep track of the birds as they learned to fly and fish. By spring of 1990 I could hardly wait to see osprey arrive in Fort Collins.
September 24, see Operation Osprey: Osprey in the Tower
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