Subject: Great Horned Owls as Migrants?
Date: Nov 11 21:51 PS 1996
From: Michael Price - mprice at mindlink.bc.ca


Hi Tweets

Does anyone know if there's a N-S Great Horned Owl (GHOW) migration in
Cascadia? I've just seen a series of photographs (some of them stunning)
taken by the remarkable observer, Evelyn Whiteside (of the pigeon-killing
Glaucous-winged Ghoul fame), of a GHOW sitting in late afternoon sunshine on
the rocks at the water's edge at the far end of the Roberts Bank Coalport
Jetty in S Delta BC; that's several treeless *miles* out into Georgia
Strait. They were taken in very late September, this year. The bird looks a
little paler and colder than the typical local race bird (B.v. lagophonus;
maybe an age difference? a footloose young bird without territory?)

Possible explanations for its presence out there are: it's a local bird
displaced by the clearcut logging that usually precedes real estate
developent here in Vancouver BC, and simply wandering around after it had
its tree chainsaw'ed --GHOW and other owls seen in daylight in
out-of-normal-context are often in this fix.

Second, it might have been out there hunting rats in the riprap along the
tideline, though this, to my knowledge is the first GHOW ever seen on the
*end* of the jetty.

Third, it might have learned to hunt/scavenge shorebirds or others killed or
injured by hitting the many overhead wires strung the 3.5 mile length of the
jetty across the normal migration and flight-lines; some peregrines,
harriers, and ravens have learned it's easier to wait for birds to hit the
wires than to hunt them, and it's a regular-enough occurrence to be a
worthwhile souce of food. Estimates of the annual kill at Roberts Bank since
1975 run to between several hundred to well over a thousand birds of all
types from Calidris shorebirds to swans. The federal Dept of Transport,
Transport Canada, which built and runs the coal and soon-to-be container
port at the end got the environmental go-ahead in the permit to build on
--in part-- a promise to bury the wires. In 1975. Well, Transport Canada is
one of the most powerful ministries in the Canadian bureaucracy and, locally
at least, has amassed a long record of broken environmental promises and
shoddy environmental practice. Historically, the local nature groups have
been either totally paralysed in the face of its power or, in rare
instances, co-opted by a few crumbs it may throw them. The Canadian Wildlife
Service, the federal agency nominally responsible for protecting our
migratory birds, has its office just a few kilometers away. I understand
they finally got around to commissioning a study to see what the actual kill
is just a couple of years ago. As Uncle Chester used to say, it sure don't
pay to hurry these things.

Fourth, as Evelyn said, it was there because GHOW are *everywhere*. Well,
yes, but-- the local race seems to prefer habitats where there's lots of
*big* trees with openings and edges onto rough pasture. The habitat-type in
which this bird sat couldn't be more diametrically opposed to usual
preferred habitat. I don't think there's ever been a GHOW reported from the
jetty itself. Nearest would be some of the cottonwood stands on islands in
the braided channels behind the foreshore, but the closest would be several
miles away.

Last, and possibly best, there's the migrational possibility. Any
out-of-context bird at the end of September at the remote end of a jetty is
a good bet to be, if not an actual migrant, then a bird in transit. And what
species could be more out of place on a rocky shoreline miles out in the
saltchuck with the nearest bunch of big trees barely visible on the horizon?

I remember that Al Jaramillo once had a GHOW show up for two days in the
first week of October 1993 in Everett Crowley Park, in SE Vancouver BC, an
area he had surveyed on a daily basis, and also a place that had had no GHOW
before. If my recollection's correct (can you confirm, Al?), he said that
particular bird seemed to be greyer and colder-colored than the local race,
and I immediately began to speculate that his owl was a bird from the
northern part of the province. It showed up at exactly the same time as a
big southbound influx of woodpeckers and passerines had hit Ev Crowley. The
coloration of the Roberts Bank bird likewise is somewhat paler and greyer
than a typical Vancouver BC GHOW.


Michael Price If asked "What is Man?" a biologist might
Vancouver BC Canada answer, "Well, 99% a Chimpanzee..."
mprice at mindlink.net -The Economist

Michael Price If asked "What is Man?" a biologist might
Vancouver BC Canada answer, "Well, 99% a Chimpanzee..."
mprice at mindlink.net -The Economist