Spring Phenology of Eagles Predicting when events will occur on the nesting grounds. Date (A00) Date (V98) Behavior     Arrival on nesting territory (Migratory individuals only. Males and females of mated pair seem to appear on territory within a short time of eachother.)     Defending territory (Watch for skirmishes with other eagles and, during nesting, with other birds. Intraspecific aggression less noticeable when pair has been established for many years.     Courtship (Displays involve aerial acrobatics and tumbling, but are rarely seen)     Nest-building (Nests made of sticks, same nest used for many years. both male and female build.)     Mating (Eagles are monogomous, meaning males and females have only one mate. Pairs stay together for life. If one dies, the remaining bird finds a new mate and usually carries on in the same nesting territory.)     Egg laying (First laid several weeks after arriving at nest site. Typicially two eggs are layed, the 2nd egg 1-2 days after first. If a 3rd egg, it's often laid a full week after 1st egg.)     Incubation (Lasts 34-36 days, begins as soon as 1st egg is layed, "aschronous incubation". Males and females take turns, but female does bulk of work.)     Hatching (1st egg hatches before 2nd egg, the same number days earlier as it was laid. Young are semialtricial: immobile, downy, eyes open, fed by parents.)     Nestling stage (Lasts 10-12 weeks, both parents share feeding responsibilities. Size differences mean older eaglets more likely to survive. Food availability )     Fledging stage (In years with plentiful food, very commmon for 2 or even 3 to fledge. This stage lasts 4-6 weeks, both parents continue to feed, but young also forage on own.) For More Information See: Peter Nye's description of nesting behaviors Journey North Links to Bald Eagle Facts Copyright 2002-2004 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form