Dear tweetsters,

August generally is a good time of year to watch ospreys (Pandion haliaetus)
at Green Lake, Seattle. Adults and immatures visit the lake regularly. The
lake is shallow, a closed system as far as fish are concerned (no streams
coming in, all but one exits to drains screened), and very rich in
nutrients, resulting in lots of fish.

The past few weeks one or two ospreys have visited the lake almost every
time of day, but the evenings, between 6:30 and 8 have yielded great
observations particularly consistent.

A few nights ago an adult pair was looking for dinner when at 7:35 PM an
immature peregrine falcon (Falco peregrinus) came in from the south, stooped
the smaller (male) osprey seven times, and flew off to the north. The adult
osprey did not have any trouble dodging out of the path of the young falcon
and did not appear terribly impressed (as in changing its behavior due to
this juvenile's "attack").

Tonight at about 6:45 I spotted one immature osprey (with the heavily
"scalloped" upper wing plumage) circling the lake in search of dinner.
Observing from along Aurora Avenue on the west side of the lake, the low sun
was illuminating every detail of the plumage as I observed the bird through
my (25x) scope. With the north wind blowing I repeatedly was treated to the
bird hovering/kiting at less than 100 m. filling the image from
side-to-side.

At 7:20 the youngster was joined by two adult birds, based on size and the
presence/absence of a "necklace", a male and a female. The three initially
circled close and some vocalizing between the immature (male) and adult
female made a few more pedestrians look up. Eventually the birds all went
their own ways, only occasionally approaching each other.

At 7:35 the adult male plunged feet-first into the lake and got a nice big
carp (estimated 25 cm), which he almost lost when he did his body/wing
shake, to rid himself of excess water. He lost his grip with one talon and
lost a lot of the altitude he had just gained, but he won the struggle and e
ventually he labored off to the northeast, not gaining a lot of height. I
eventually lost him behind trees at 7:42. At that time I found the female
had made a catch too (another 25 cm carp). She had considerably less
difficulty with her fish than the male, easily gaining height and clearing
some of the structures the male barely cleared, with hundreds of feet to
spare. What had taken the male almost 5 minutes took her about 3. I lost her
heading northeast on an almost identical course as the male at 7:45.

I have no idea where there may be a nest in that direction, assuming the
birds would head for their nest/territory if they were going through all
this trouble to carry the fish off.

With the adults gone I turned my attention to the youngster again. He
plunged in the water several more times coming up empty every time and I was
beginning to think he would be going to bed hungry tonight when, at 8:07 he
plunged down and came up with a 15 cm trout (the lake is stocked with
rainbow trout every year). It was a bit of a struggle to hang on to the
wriggling fish, but he managed. At 8:10 I lost this guy as he disappeared
over trees of Woodland Park heading south (in that direction the nearest
territory I know is south of the West Seattle Freeway bridge 9 miles/14.5 km
away).

Estimates of mortality in the first year of life for ospreys vary from
40-50% (source: A. F. Poole, Ospreys, Cambridge University Press, 1989).
Tonight was a neat example of why so many young birds will not survive their
first year. The adults made their catches in 15 and < 22 minutes (from my
spotting them). The youngster however, from the time I saw him, spent 82
minutes flying around the lake before making a smaller catch than the
adults. It's going to be a tough year for all those youngsters striking out
on their own these days...

Martin Muller, Seattle
MartinMuller at email.msn.com