Then there were the two beautiful birds, offering prolonged looks, at Fernhill
Wetlands in Forest Grove in late July 2013 - not a colony, but a start. (I
wish.)
George Neavoll
S.W. Portland
Begin forwarded message:
From: Jeff Gilligan <jeffgilligan10@xxxxxxxxx>
Subject: [obol] Re: on Tricolored Blackbirds
Date: March 21, 2016 10:04:40 AM PDT
To: 5hats@xxxxxxxx
Cc: OBOL Oregon Birders Online <obol@xxxxxxxxxxxxx>, vanwing
<vanwing@xxxxxxxxxxxx>
Reply-To: jeffgilligan10@xxxxxxxxx
I found a small colony in Portland off North Gertz Road in about 1967 (I
would have to look up the date to be sure) within a hundred yards or so from
where the Portland birds were found years later. Their presence in Portland
was a big surprise. I suspect that they have been scattered colonies in
northern Oregon for a long time. There were very few birders in Oregon who
could identify many species even into the 1980s. In addition, field guides
just weren't very good.
Jeff Gilligan
On Mar 21, 2016, at 8:07 AM, 5hats@xxxxxxxx wrote:
Paul Sullivan's recent discovery of Tricolored Blackbirds in Gilliam County
prompted this post.
Prior to about 1980 the only known breeding locations for the species
were located in southern Oregon, primarily in Klamath and Jackson Counties.
Then sometimes around the early 1980's ( I don't have the exact date) a
small colony of them was discovered near Camp Hancock in southeastern Wasco
County. This spot is approximately one hundred seventy miles north of any
breeding location known to exist at that time. Within a very few subsequent
years other colonies were located near Hermiston in Umatilla County,
Prineville in Crook County, and at the Painted Hills Unit of the John Day
Fossil Beds near Mitchell, Wheeler County. There were also reports of a few
birds near Portland, Multnomah County, as well as in other scattered
locations in the north-central part of the state, where they seem now to
have become regular. The species has been recorded in Wasco, Sherman,
Gilliam, Morrow, Umatilla, Wheeler, and Crook Counties, with breeding
reported in most of them.
It is speculation on my part, but I have long suspected that this spread
of the species into north-central Oregon was not the result of a range
expansion from southern Oregon, but rather a dispersal of birds from a
previously unknown breeding location closer to the area, and there is at
least some data to support the hypothesis. About twenty miles northeast of
Madras, very near the now defunct town of Willowdale, there used to be a
large cattail marsh on the west side of US highway 97. This particular
marsh was a couple of miles long, probably at least a mile wide, and
completely inaccessible. The cattails which grew in the marsh were higher
than a man's head, and there were no elevated places along the highway from
which a person could see out over the marsh. It is not at all unreasonable
to think that an inaccessible marsh of that size could have hosted a colony
of Tricolored Blackbirds without anyone ever detecting their presence. I
believe it was in 1979 that the marsh was drained and converted to cropland.
My records show that on June 9,1980 at Willowdale I saw a Sora at dawn in
what had formerly been a cattail marsh. It was the year after that marsh
was drained that the Tricolored Blackbirds were reported at Camp Hancock,
which is only a few miles to the northeast, and subsequently began to be
reported in other spots in the north-central portion of the state.
If Tricolored Blackbirds did once have a colony at Willowdale (and it
cannot be proved they did), it is interesting for several reasons. (1) It
means that the species had a breeding location in Oregon, unknown to
birders, nearly two hundred miles north of any previously known breeding
location. (2) It explains the sudden and surprising spread of the species
into the north-central portion of the state. (3) it suggests that the
species is perhaps more adaptable than previously thought. Tricolored
Blackbird is known to be a colonial nester, most colonies being made up of
numerous pairs or females and polygamous males. Most of the colonies which
now exist in north-central Oregon are relatively small. I never counted
birds, but the largest colony I have observed was the one which nested for a
while between Prineville and O'Brien. It had maybe a couple of hundred
birds. The one I saw near Hermiston had perhaps half that many. The one at
the Painted Hills Unit of the John Day Fossil beds I do not think had over
twenty birds total.
One of the thing which makes tracking this species a bit difficult is
that their breeding colonies in the north-central part of the state seem to
shift locations from time to time. There are undoubtedly people who know
far more about the numbers of birds and the locations in which they breed
than I do. I am only piecing together what little data I have from
occasional trips to the area, and none of it has hard documentation in terms
of numbers. However the continuing reports of this species in that section
of the state suggests it has successfully colonized a new area, and is
continuing to expand its range within that area. I present this post to
give this apparent range expansion a bit of historical perspective.
I might also add that Paul's recent discovery of the species in Gilliam
is not unprecedented. Once previously he found a small breeding colony of
them along Rock Creek near the bottom of Wolf Hollow Road south of Olex. I
have looked there several times since and seen only Red-winged Blackbirds.
I would encourage those who know more about the presence and spread of
this species into north-central Oregon to contribute to this thread.
Darrel
.
