Spring Phenology of Eagles
Watch for these events to occur on the nesting grounds.

Date Behavior
  Arrival on Nesting Territory:
Migratory individuals only. Males and females of mated pair seem to appear on territory within a short time of each other.
  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.
Displays involve aerial acrobatics and tumbling, but are rarely seen.
  Nest Building:
Nests made of sticks lined with softer grasses and mosses. The same nest is often used for many years. Both male and female build.
Eagles are monogamous, 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 laid, the 2nd egg 1-2 days after first. If a 3rd egg, it's often laid a full week after 1st egg.
Lasts 34-36 days, begins as soon as 1st egg is layed, "asynchronous incubation." Males and females take turns, but female does bulk of work.
1st egg hatches before 2nd egg, the same number days earlier as it was laid. Young are semi-altricial when just hatched: immobile, downy, eyes open, fed by parents.
  Nestling Stage:
Lasts 10-12 weeks, both parents share feeding responsibilities. Older eaglets more likely to survive due to size/age differences due to competition for available food.
  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.