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 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
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.