If you are interested in a regional update, with data and interpretation,
dealing with the massive and unprecedented Blue Jay invasion we have
experienced this Fall, read on. This information will also be available, as
are all previous installments, on www.IdahoBirds.net

Harry Krueger
hkrueger at cableone.net

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Pacific Northwest and Great Basin Blue Jay Invasion Update



Through the last day of November at least 319 individual Blue Jays had been
reported from a wide variety of habitats and geophysical areas in Idaho,
comprising a carefully conservative 191 locations separated by enough
distance to reasonably assure no duplication of observations (though Blue
Jays are known to range widely in non-breeding seasons). This averages out
to 1.67 birds per location, helping to reinforce the fact that the movement
of birds throughout the Northwest and northern Great Basin is not one of
isolated, individual birds, but often small groups moving through an area
together. In fact, Blue Jay "migration" in one race has been shown to be of
2-100 birds (N. L. Stone 1976. Migratory behavior of the Blue Jay
(Cyanocitta cristata): a field and laboratory study. M.S. thesis, Clemson
Univ., Clemson, SC). Also of note is the fact that in approximately 40% of
reported observations this season, Blue Jays were noted in association with
Steller's Jays, which also are being noted in unprecedented numbers for this
related corvid species in what is perhaps a larger swath of the country as
far west as the Pacific Coastal areas west of the Cascade range. (See
article on Steller's Jay dispersal at <http://www.idahobirds.net/>
www.IdahoBirds.net )



Oregon's influx of Blue Jays has slowed, with a grand total of at least 30
birds from 16 locations gleaned from OBOL posts and private communications.
While some of the first birds seen are no longer being reported, others seem
to be staying in the areas of their discovery. All birds still being seen
are from the central and eastern portions of the state. As in Idaho, often
these birds are seen in the company of Steller's Jays or loosely associated
with them, a species whose numbers in the lowland areas of Oregon are much
increased beyond what would be considered "normal." As in large sections of
Idaho, there are portions of eastern Oregon that have little consistant
field coverage when compared to the western regions, yet these are the very
areas were Blue Jays have been found and are also closest to the Idaho areas
of high density.



Washington finished off October with 41 birds at 20 localities, increasing
by November's end to 72 birds at 28 locations. Most noteworthy here is the
fact that although the bulk of reports came from the eastern portion of the
state, there were also two coastal reports. Since it is surmised that the
movement of jays has been north to south, judging by both subspecies
identification and population densities, the birds in Port Hadlock and on
Lumni Island probably moved in a more north to southwest direction, counter
to the overall trend, and therefore could be much more considered vagrant
break-offs from the larger invasion path. As in many cases in Oregon and
Idaho, these birds too were seen in association with Steller's Jays.



Montana continues to be a bit more unclear when it comes to the magnitude of
the jay incursion. Because there are areas of the state which host Blue
Jays year round, including areas in the western mountains, observing them,
even if in above average numbers, might not be deemed "report worthy." But
even a veteran and knowledgeable observer, who previously just could not get
excited about the species' incursion into the state, was led to remark after
seeing 8 birds at his feeder, ".I'm on board now regarding the influx" (Dan
Casey, MOB list serv post, 11/21/04). Utilizing figures supplied by birders
who considered the presence of Blue Jays worthy of listing on the state list
serv or a private e-mail, 198 birds from 56 separate locations were the end
of month totals, but for reasons already enumerated, Montana birders'
"acceptance" of Blue Jays as unusual or rare is not always forthcoming,
therefore these figures are probably somewhat higher at the very least.



Utah comes in with at least 29 birds from 15 sites, while neighboring Nevada
has yet to report a single bird. Wyoming birders have not mentioned the
species other than the one observation enumerated in the last "Update" in
<http://www.idahobirds.net/> www.IdahoBirds.net , and from the obvious
reports, the British Columbia situation has also remained static.



Newspaper articles have been run in four widely separated sections of Idaho
(Boise, Lewiston, Salmon, and Idaho Falls) focusing on the unusual invasion
of this species into the state. After each piece appeared there was an
appreciable increase in the number of reports of Blue Jays seen or coming to
feeders, indicating that earlier reports from what were mainly birdwatchers
were limited in number. As an example, after an article was published in
Salmon, the number in this small, largely rural area shot up to 53 very
carefully documented different birds observed.



To give an idea of the probably unprecedented massiveness of this movement
of birds, consider the following possibility for Idaho. Allowing that
conditions are equal across the state (which they are not) and extrapolating
numbers uniformly across the state, while keeping in mind that vast areas of
Idaho are unpopulated, no less virtually un-birded, with little or no
informational connection to field ornithologists...an estimated number of
birds in the state this Fall could equal 5400! How is that possible?
Approximately 8% of the state's land is covered in the specific and counted
numbers currently available, with a generous estimate of 70% of the birds
present in this area observed, therefore giving us 456 birds in 8% of Idaho.
Carry that over to the remaining 92% of the Gem State, since birds have been
observed in all sections and habitats, multiply by 12.5 (a proportion of
known to unknown of 1:12.5), and you have 5400. Granted much of southern
Idaho, especially the Snake River Plain and south to the Nevada and Utah
borders is flat, often treeless topography that is reasonably inhospitable
to Blue Jays, but then conversely much of the rest of the approximately 2/3
of the state is more forested and corvid friendly, yet much less "covered"
by potential human observers. While this number may seem an excessive
exaggeration, looked at from another perspective, we may ask "Are there
another 100 similar "Salmon situations" scattered throughout Idaho?" Or put
differently, can there be 16 times as many Blue Jays in the state as have
been reported in such a small total area by so few people...16 additional
birds for each one "discovered?" The possibility is definitely there and
5400 is perhaps not as imbalanced as it may sound at first. But even were we
to arbitrarily cut that number in half, we would still have 27,000 Blue Jays
in a state that only reported 6 last Fall!



There has been no definitive evidence (with numerous photos submitted for
consideration...some marginal, others very good), of any subspecies involved
in this massive movement other than C. c. bromia. With as many birds in
this invasion as there seem to be, the possibility of another race present
is possible, but with all information we presently have, it is not probable
(See previous updates dealing with subspecies and their identification).
There has been one dead bird/specimen collected in Grangeville, ID which to
date has not been examined. Also, it should be noted that any migratory
movement of these birds has in all likelihood ceased. What are being noted
now as "new birds" are undoubtedly birds that have already taken up
temporary residency in a particular area but are only now being discovered
as they move about in a more limited geographic locale or are "discovered"
by interested and/or informed observers. Results from Christmas Bird Counts
should provide additional population data for the start of the winter
season. A potential phenomenon to watch is that research has documented
that jays captured and marked in eastern North America as adults during
winter have been recaptured substantially farther south in subsequent
winters (P. A. Stewart 1982. Migration of Blue Jays in eastern North
America. N. Am. Bird Bander 7: 107-112). Will this too happen here in the
West? Also, Blue Jays have been shown to be especially susceptible to major
snow storms and blizzards (J. J. Hickey 1952. Survival studies of banded
birds. U.S. Fish and Wildl. Serv., Spec. Sci. Rep. Wildl. 15: 1-177), a
potential cause of mortality during the coming season in these birds
wintering in areas of the Northwest and Great Basin.