BLUE JAY Invasion in Idaho -- 2004

Last Fall there were only 6 Blue Jays recorded in all of Idaho; the year before 27 were encountered, marking the best season in three years. This species is an expected annual visitor in limited numbers, and reports from various parts of the state are no surprise.  But in the last one-and-one-half weeks (beginning 28 September, 2004) the number of birds from virtually every corner and habitat in the state has been phenomenal. To date (8 October, 2004; SEE UPDATES BELOW) there have been at least 44 different birds from 25 separated locations reported to the three listservs covering Idaho (IBLE, SWIBA, Inland-NW-Birders) and to me personally, or to others of which I have been made aware. As with any statistic, we can only deal with actual known numbers, but considering the vast areas of the state where there is no or extremely limited birding coverage, these numbers must be but a fraction of the total number of birds present in Idaho presently. As with some of the other species that have been noted to have made dramatic movements (often referred to as "irruptions") in the state over the past few weeks (i.e. Mountain Chickadee, Chestnut-backed Chickadee, Red-breasted Nuthatch, White-breasted Nuthatch, Pine Grosbeak, Evening Grosbeak), Blue Jays are appearing in previously "uncharted territory" for the species.  This is all the more amazing since this is the only bird of the other previously mentioned species where breeding has not been demonstrated to take place anywhere in the state.

Where are these birds coming from, and why are they coming into the state in these numbers now?

Currently there are three recognized subspecies of Blue Jay in North America (note that juveniles of all three subspecies are noticeably lighter in coloration until the end of August and beginning of September, and indistinguishable from each other):

Differentiating these three subspecies in the field is not an easy task.  C.c. bromia is the largest of the trio, but this is an almost impossible trait to accurately observe.  Of greatest help here is the fact that it is darker blue on the uppersides than each of the others, with a slight or no purplish wash. To be looked for here is an all blue nape, also often with blue above the black "necklace," sometimes extending into the throat area.   The somewhat smaller C.c. cynotephia exhibits duller upperparts, including a pale blue color with purplish wash.  This bird generally has a dull grayish-white, rather than blue nape, with little or no blue tint to the feathers.  C.c. cristata is almost impossible to separate from C.c. cynotephia in the field, either by size or color.

Considering the range and normal movements of C.c. bromia, it would seem that this is the expected visitor, if not occasional breeder, in Idaho.  As with other species that are also primarily more eastern, a portion of the population bends over/north of Idaho into the mountains of Alberta and western British Columbia.  Since this population also moves south during the fall-winter of each year (to what extent, we are not sure), reason would dictate that some birds would be observed in Idaho, as well as southwestern British Columbia, Washington, and Oregon.  C.c. cynotephia is a bit more problematical, since any movement is thought to be southerly, actually staying within the bounds of its breeding range.  If there is also a westerly or southwesterly movement, this would account for the records from Colorado, Utah, and even Southern California. 

I have received photo evidence of what appears to be C.c. bromia from the Salmon, Lemhi County area of the state (30 September, D. Faike), but also photo documentation of what could be C.c. cynotephia from Garden Valley, Boise County (29 September, R. Foote).  Interesting to note is that the Blue Jay (the subspecies of this bird has not been established) that was reported from near Lewiston, Nez Perce County (28 September, J. Clark) was in the company of what appears to have been a bird of the interior race of Steller's Jay, Cyanocitta stelleri macrolopha (distinctive white on forehead and above eyes), breeding in some of the same area as C.c. cynotephia, but apparently seldom reported from Idaho. 

The question remains as to where from do the present Idaho birds originate?  And then even in a "normal year," what race do we have in the state?  And is that norm the same, only in larger numbers, this year, or do we have the "normal visitors" as well as a larger population from another subspecies?  Other birds being driven "out of place," such as Chestnut-backed Chickadee are from a more northerly population.  Is the food supply in the "north" a factor in the Blue Jay movement (which would point to C.c. bromia) or is this a phenomenon originating to our east (where both C. c. cynotephia and C. c. bromia breed)?

Be warned that the three races are clinal where their ranges meet, in other words, physical differences overlap and are gradual at these points of contact. It is here (birds from the east of Idaho) that the distinctness between C.c. bromina and C.c. cyanotephia may be less distinct and mixed. Obviously, when looking at birds that have possibly moved from such an area into Idaho, their identification may be less than definite. But because of the placement of this clinal geographic area, any bird seen in Idaho that exhibits a fairly uniform darker blue back and blue nape can confidently be assumed to come from north of the state.

Photos and careful observations, and accompanying descriptions, would provide necessary clues, if not outright answers, to these questions.

UPDATE -- As of the end of the day, 10/15/2004, the number of Blue Jays that have been reported from sites in and throughout the state of Idaho equal 89 (up from 45 on 10/9). (These are reports that have been posted to any of the three list serv services in Idaho: IBLE, SWIBA, Inland-NW-Birders, or that have been reported to me directly or through a third party.  Every effort has been made to discount possible duplicate sightings.)  Currently these observations come from 53 (up from 25 on 10/9) different locations in all areas of the state and a variety of habitat. This is the largest movement of this species into the state since at least the 1970's, if not before.

As to subspecies identification:  All pictures that have been clear enough for noting necessary id points point to the northern race, Cyanocitta cristata bromia, which breeds from central Alberta and just into north-central British Columbia, through northeast Nebraska to Newfoundland, and down into south-central Virginia. One reported bird that I am aware of was still in its juvenile plumage (usually shed by the beginning of September), which is much grayer and more unlike the C.c. bromia adult, in some respects very similar to  C. c. cynotephia, which breeds and winters from southeast Wyoming through New Mexico, to Nebraska through south Texas. Thus far I have not received a description, photo, or video of a bird that could safely be ascribed to C. c. cynotephia, including, upon closer study, the Garden Valley bird(s) referenced above. (See salient points for subspecies identification above).

Blue Jay is also occurring in western Montana, Oregon, Washington, and British Columbia, but we have little to nothing from western Wyoming, Nevada and Utah, which are places we might expect to hear from if these birds were C. c. cynotephia, although a continued southward movement of C. c. bromia would not be illogical.

UPDATE -- As of today, Saturday, 23 October, 2004, there have been at least 137 different individual Blue Jays observed from 81 different and separate locations throughout Idaho. As before, all of these reports are gleaned from the IBLE, Inland-NW-Birders, and SWIBA listservs, as well as personal e-mail and telephone communications.

Areas from which there have been no previous reports continue to be added to the overall distribution picture as well as increases in numbers from areas providing earlier reports already tallied. A particular effort has been made to avoid any possible duplication of individual birds present at any location, preferring to rather err on the side of caution and a more conservative view of totals than adding up bigger, but possibly redundant numbers.

The number of sightings from Washington, Oregon, and Montana also continue to increase, although apparently not at the same overall rate as in Idaho (note that there are places, such as Kalispell, MT that have seen a consistent and steady increase of birds over the past decade). Observations from eastern Washington and western Montana are most frequent, a fact consistant with the thesis that these birds are coming from the northern subspecies Cyanocitta cristata bromia, although there is a report this week from Riverton, Wyoming (10/16/04), which is in the west-central, Wind River district of the state, where the active reporting observer states that this is the first sighting of Blue Jay at his location in three years, and also a probable report from the Portland area of Oregon (Clackamas).

All pictures submitted to me that are detailed enough and which I have been able to carefully examine (including two from Montana) are consistant with C. c. bromia. (See the Blue Jay pictures from Genesee, Latah County, Idaho of October 16 for a good example of the distinguishing features of C. c. bromia, as has been described [above]).

Looking farther east, beyond our area of the country, South Dakota is actually experiencing fewer Blue Jay reports than usual, while along the East Coast there is a huge movement being noted in places like Cape May, New Jersey and the Carolinas, both of which can be influenced by movements of C. c. bromia, which is found coastally all the way from Newfoundland to Virginia.

Some have suggested that the birds are "moving south" because of a very plentiful crop of acorns and other staple foods, but it is incorrect to focus on what is happening at the bird's destination or potential over wintering areas. Why? Because movement in response to food availability is caused by conditions of supply in the species' breeding or normal over wintering areas.

UPDATE -- In Idaho as of today, Sunday, 31 October, 2004 there have been 204 different Blue Jays reported from 131 different locations. As in previous reports, numbers are purposefully conservative, taking care to not count any possible duplications of either individual birds or localities of occurrence. Not included in these numbers are birds from the Coeur d'Alene area that are clearly Steller's Jay x Blue Jay, have now been seen for multiple years, and are therefore suggestive of breeding of these two species in the area.

Observations in Montana are also continuing to increase with a comparable 176 birds from at least 51 locations, although a major difference with Idaho being that there are locations in Montana that report having Blue Jays in all seasons (Kalispell, Whitefish), while along with the rest of the region, still experiencing a noticeable increase in numbers since the latter portion of September this year. Some localities such as Glendive report the species "all over town" beginning in October, and other notes from places such as upper Yellowstone state their birds to be the "first in several years."

There have been no new reports from Wyoming other than the one reported last week, while Utah is currently experiencing an increased influx suggestive of invasion movement originating from the north of the state. Presently the Beehive State has at least 13 birds from as many as 10 locations, the most southerly being from the central part of the state (Utah County). Nevada has yet to report any Blue Jays, although there is what seems to be a recently documented altitudinal movement of Steller's Jay to more low lying areas than those in which the birds breed and normally reside.

Oregon has tallied 21 apparently different birds from at least 12 locations, all of which are east of the Cascades (except one probable "mother relayed" observation in Clackamas). For a good photo of a Blue Jay from central Oregon (Redmond) see This, along with numerous other pictures received, seems to point to the birds entering the region being from the more northern subspecies C. c. bromia. (Especially see for a good representation of this race.)

In Washington there are currently 41 reported sightings from 20 different and separated locations, all in the eastern half of the state. Spokane County is the only area of the state where Blue Jays are listed in the Washington County-by-County Checklist/Abundance list as occurring yearly - all other counties are "red" (less than 5 records) or "orange" (5+ records) The observation the farthest west seems to be from Bridgeport, Douglas County.

As but a minimal indicator of the magnitude of this Fall's invasion, there have been 454 separate birds sighted from 224 different localities in the above mentioned states, with the highest concentrations continuing to be from Idaho and Montana. (British Columbia has reported at least 3 interior records in September/October.)

Historically, the range of the Blue Jay has expanded, beginning in Canada in the 1940's, and continuing in dramatic fashion in the 1970's, with successful nesting reported from New Mexico, Wyoming, Montana1, Oregon2, and British Columbia3, 4. Blue Jays have now also been documented in all areas bordering those aforementioned states. The percentage of the population of Blue Jays that regularly migrates north to south (which the present movement of C. c. bromia apparently is) in the eastern portion of the continent is > 20%5.



1 Smith, K.G. 1978. Range extension of the Blue Jay into western North America. Bird-Banding 49:208–214.
2 Van Horn, D. 1978. First breeding record of a Blue Jay in Oregon. Murrelet 59:70.
3 W.E. Godfrey 1986. The birds of Canada. Rev. ed. Natl. Mus. of Can., Ottawa.
4 Campbell, R.W., N.K. Dawe, I. Dawe, I. McTaggart-Cowan, J.M. Cooper, and G.W. Kaiser. 1997. The birds of British Columbia. Vol. 3: flycatchers through vireos. Univ. of British Columbia Press, Vancouver.
5 Stewart, P.A. 1982. Migration of Blue Jays in eastern North America. N. Am. Bird Bander 7:107–112.

Pacific Northwest and Great Basin Blue Jay Invasion Update

December 12, 2004

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 birds1. 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).

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 October 23 “Update” above, 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 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 winters2. Will this too happen here in the West? Also, Blue Jays have been shown to be especially susceptible to major snow storms and blizzards3, a potential cause of mortality during the coming season in these birds wintering in areas of the Northwest and Great Basin.



1 N.L. Stone. 1976. Migratory behavior of the Blue Jay (Cyanocitta cristata): a field and laboratory study. M.S. thesis, Clemson Univ., Clemson, SC
2 P.A. Stewart. 1982. Migration of Blue Jays in eastern North America. N. Am. Bird Bander 7:107–112
3 J.J. Hickey. 1952. Survival studies of banded birds. U.S. Fish and Wildl. Serv., Spec. Sci. Rep. Wildl. 15:1–177

All data compiled and maintained by Harry Krueger. Please notify your local listserv or Harry about Blue Jays you encounter.