Greetings,

Sorry this is late (I'm on digest mode).

The Bald Eagle (Haliaeetus leucocephalus) "arboretum" nest is, as pointed
out previously, actually the Broadmoore Golf Course nest. Several years ago
eagles did build a nest in a tree on Azalea Lane in the arboretum, but I
guess once spring sprung they discovered exactly how busy that area gets
with people. That nest never became active.

Last year was the first year the Broadmoore Golf Course nest was active, the
birds were lagging almost six weeks behind most other area nests. Two or
three days after (presumed) hatching, the feeding stopped. It failed for
unknown reasons.

This year incubation behavior started much earlier (mid-March) but to me it
looked like just around hatching time something went wrong again. No birds
were seen in the nest. Even if the egg(s) had hatched, an adult should have
been brooding the chick(s). I chose days with crummy weather to observe, to
make sure I would see brooding behavior. Both birds were seen in the area
but not incubating, brooding, or feeding (a) chick(s). I assumed it failed
again. Again I don't know the reason; I did note the nearest golf course
building was being re-roofed (cause and effect?).

However, this past Monday I went to double-check and both adults were
present. One on a branch next to the nest, the other busy poking/arranging
stuff in the nest, then assuming what may have been brooding posture.
I did not have enough time to stay and determine what's going on exactly
(only had 15 minutes). I hope to be able to spend enough time soon to see
what's going on. I would love to be wrong about it having failed.

On the question of immature/subadult eagles hanging around.
King County now has 32 (or so) Bald Eagle nests. That means a minimum of 64
adults present. Add a few non-breeding adults for good measure. By early
July the first young from this year will start flying around (after about 11
weeks in the nest). Say an average of 1.5 young per nest (from 1 to 3).
Already we can expect to have 100+ eagles in the county this summer. Add to
this sub-adult, non-breeding birds. Between fledging and sexual maturity
Bald Eagles have to survive for 4-6 years. Continent-wide only about 10% of
the fledglings will survive to sexual maturity (not unusual for a
top-of-the-food-pyramid predator). During that time span some of these
sub-adults will be present in King County as well. This shows that we have a
healthy population of Bald Eagles here. This also shows that unless you can
recognize an individual by plumage markings or see it in/near a nest there's
no reliable way to say who you're looking at. I am not aware of any studies
that show that sub-adults return to their natal territory. Given that young
are still in the nest right now, seeing an adult interact with a sub-adults
does not mean they are related.

For example: Last Monday afternoon the Green Lake female was circling high
over the lake. A male first-year bird (all dark brown, irregular white
beneath wings, all flight feathers same length, considerably smaller) showed
up and made some "passes" at her, she dodged him. It looked more like play
than aggression. Within a minute two more eagles showed up from the south
(no idea where they "belong"). One adult male, one sub-adult (dark brown but
with jagged trailing edge of the flight feathers indicating it has gone
through at least one [partial] wing molt) female.

As the four of them circled high over the lake, the Green Lake male
apparently couldn't "stand it anymore." He left the nest with the 18 day-old
chick and started rapidly climbing toward the circling birds. He only got
about halfway before all three "visitors" left the area, drifting east. The
male turned back toward his nest, the female eventually joined him at the
nest.

One last point. Please respect property rights. If you wish to observe a
nest located on private property please do so from public streets
(regardless of what you look like), unless you have permission from the
property owner. Specifically, there are several good vantage points in the
neighborhood along the east side of the Broadmoore Golf Course. I watch from
38th Avenue E. anywhere between E. Croquette and E. McGraw. There's nothing
you will see by trespassing that you cannot also see from these vantage
points. It will just make us birdwatchers unpopular with property owners
(and rightfully so).

Martin Muller, Seattle
MartinMuller at email.msn.com