The Peregrine Breeding Season
Prior to nesting, peregrines engage in a courtship period that begins in February and extends into March. During their courtship, you can see spectacular aerial flights by the male, ledge displays by the pair as they bow to each other and vocalize, prey transfers by the male to the female (courtship feeding), and copulation.
Generally, incubation begins with the second egg, and both birds share incubation duty. You may notice that the incubating bird frequently turns and shifts the eggs; this prevents the embryos from sticking to the shell and dying.
Banding a peregrine chick at the East Channel Bridge (Mercer Island)
Photo by Pat Little
After an incubation period of 32-35 days, the eggs will hatch, usually within a 48 hour period. This is known as synchronous hatching. Near hatching time, watch the adults as they listen to the young calling from within the eggs. Hatchlings literally saw their way out of the eggs using a special egg tooth on their beaks.
Development of the Young
Young peregrines are called eyasses (pronounced eye-yesses). They will fledge (i.e., take their first flight) 42-45 days after hatching. The smaller males develop faster than their larger sisters and usually fledge first. Take note of the dramatic changes in appearance around 3-1/2 weeks of age, when the young falcons go rapidly from being fluffy downies to fully feathered, sleek falcons. The Seattle nestlings usually fledge around mid-June.
A young peregrine just about ready to fledge
photo by Pat Little