Eagle Breeding Dates
Doug Carrick, who is a volunteer monitor on Hornby Island, compiled these dates from 13 years of observing approximately 15 different breeding territories.
RETURN FROM MIGRATION: October 2, give or take 3 days.
MAJOR NEST BUILDING TIME: From October 20 to November 15. Bringing branches to nest, large ones around the outside and fine twigs on the inside.
WINTER SURVIVAL TIME: November 15 to January 31. With shorter and colder days, nest-building stops. Much of their time is spent getting food, mostly fish but also winter-weakened birds and ducks.
MATING: Think of St Valentine’s Day, February 14 (a suitable time for mating) – but include the two weeks before and after this date – in other words, the whole month of February. Eagles are also seen mating in the first half of March, just a week or two before laying eggs But at no other times in the year.
FINAL NEST PREPARATION: A second flurry of nest-preparation takes place from mid-February to mid-March – adding more branches, followed by soft materials like dry grass and moss.
EGG LAYING: March 25, plus or minus one week. A second egg 2 or 3 days later.
BROODING: The male and female take turns sitting on the eggs for approximately 35 days – from March 25 to May 1, plus or minus one week. One could consider the month of April as the “brooding” month.
CHICKS HATCH: May 1, plus or minus one week.
CHICK DEVELOPMENT: Peeps can be heard by June 10 (see chart below)
- Sitting on edge of nest by June 20
- Flapping wings by June 25
- Flapping and Jumping by July 10
FIRST FLIGHT: July 25, plus or minus one week. (85 days after hatching)
MIGRATION OFF ISLAND: from mid-August to September. This migration includes adults, new eaglets and any other non-breeding eagles. All eagles go.
ADULT EAGLES (0NLY) RETURN TO ISLAND: October 2, plus or minus one week
IMMATURES STRAGGLE BACK TO ISLAND: One or two arrive back in November, a few in December and increasing numbers in the next few months.
Dates will be earlier in southern Vancouver Island and the Fraser Valley and later in northern Vancouver Island and up the coast
Bald Eagle Chicks: Colour/Size and Estimated Age
Below is the chart that the late Rick Davies - Senior Wildlife Biologist, MELP - used (perhaps developed?) in the early 1990's to estimate the age of chicks during helicopter surveys.
| Colour and Size | Estimated Age |
| White and Small | 1 week old or less |
| Grey and Small | 2 weeks old |
| Grey and Larger | 3 weeks old |
| Grey and Brown | 4 - 5 weeks old |
| Mostly Brown | 6 weeks old |
| Brown | 6 - 8 weeks old |
| Brown and Full Size | 9 - 12 weeks old |