The Scrub-jay complex may become more complex

Contributed by Mike Patterson, Astoria, OR

There are currently 3 recognized species in the North American Scrub-jay complex, Western Scrub-jay, Island Scrub-jay and Florida Scrub-jay.  The latter two represent distinct, disjunct populations that have unequivocal structural and behavior differences from the broadly distributed Western Scrub-jay, not to mention very well defined, isolated ranges and little or no chance of overlap between them to muddy identification.  This may soon change with the addition of two additional scrub-jay species that have ranges and field marks that are not so neatly demarcated.

Depending on who you want to believe there are somewhere between 8 and 14 subspecies under the Western Scrub-jay umbrella, all of which fall into one of three larger groups: California Jay, Woodhouse's Jay and a Mexican form called Sumichast's Jay (Curry et al. 2002; Pyle 1997).  There is growing genetic evidence that these three groups may represent three distinct species.

The latest evidence comes from a paper published in BMC - Evolutionary Biology: Speciation in Western Scrub-jays, Haldane's rule, and genetic clines in secondary contact (Gowen, et al.  2014).  The study was designed to test gene flow along the zone of contact between interior (Woodhouse's) and coastal (California) Scrub-jays by exploring the mechanisms of Haldane's Rule.  As we all probably learned in High School biology, hybridization between two species generally produces offspring which are either sterile or have significantly reduced fertility.  This is a mechanism of reproductive isolation that helps to define different species.

Haldane's rule applies to incomplete reproductive isolation.  Again, going back to High School Biology, gender is determined in most animal species through a difference in the combination of sex chromosomes.  For mammals, XX produces females (homogametic gender) and XY produces males (heterogametic gender).  In birds, females are the heterogametic gender.  The letters ZW are traditionally used for female heterogametic species (ZZ would be males).  Haldane noted that, in many cases of incomplete isolation at hybrid zones, hybrid offspring of the heterogametic gender are much more likely to be absent, rare or sterile than the homogametic gender.  This complicates genetic studies for birds, because mitochondrial DNA (mtDNA), which is only inherited from the mother, is passed to next generation at a much lower rate than nuclear DNA which can be passed by both males and females.  Avian genetic studies which use only mtDNA may misrepresent the degree of gene flow along contact zones.

So, the Gowen, et al. study collected 689 specimens from throughout the range of Western Scrub-jay.  They sequenced both mtDNA and nuclear DNA to compare rates of gene flow along zones of contact and were ultimately able to demonstrate a statistically significant difference in the rate of mtDNA movement along the zone of contact when compared to nuclear DNA as predicted by Haldane's Rule.

In the process, they were able to do the most comprehensive, range-wide genetic sequencing study to date on Western Scrub-jays.  The study shows a strong genetic difference between Coastal and Interior Scrub-jays with a narrow zone of hybridization that exhibits partial reproductive isolation along heterogametic lines (Haldane's Rule).

Structure scans from 13 nuclear microsatellite loci highlighting genetic clusters (from: Gowen, et al.  2014)

This supports the proposition that Coastal and Interior forms are separate species.  The study further showed that the Western Scrub-jays in southern Mexico also qualify for elevation to at least one species (and arguably three, pending more study).

This study did not sample any of the scrub-jays in Central or Eastern Oregon and provides no direct guidance into the status of birds in interior Oregon or Washington.  Birds occurring in Klamath and Harney County are presumed to be from the Coastal group based on phenotypic and behavioral characters.  Coastal Scrub-jays show bright blue upper parts and white under parts.  They also show a well defined blue necklace and a heavy bill.  These birds are also strongly associated with residential areas in eastern locations.  Interior (Woodhouse's) Scrub-jays are a dull blue with very gray under parts, little or no necklace and a narrow bill.   This group is sparsely distributed in pinyon-juniper scrub.

Any claims of Woodhouse's Scrub-jay in Oregon or Washington should be meticulously documented with photos and comprehensive notes on habitat and behavior.

References

Curry, Robert L., A. Townsend Peterson and Tom A. Langen. 2002. Western Scrub-Jay (Aphelocoma californica), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/712

Gowen, F. C., Maley, J. M., Cicero, C., Peterson, A.T., Faircloth, B.C., Warr, T. C. and McCormack, J.E.. 2014. Speciation in Western Scrub-Jays, Haldane’s rule, and genetic clines in secondary contact. BMC Evolutionary Biology 2014, 14:135

Pyle, P. 1997. Identification Guide to North American Birds. Slate Creek Press, Bolinas, CA.

Tufted Duck: A historical perspective of this former review list species

By Dave Irons -- OBRC Member

Tufted Duck first appeared in Oregon on 14 Feb 1960, when the late David Marshall found an adult male wintering on a small pond in Laurelhurst Park in northeast Portland (Nehls 2003). This bird remained to at least 26 March of that year. It would be 18 more years before another Tufted Duck was detected in the state. On 15 October 1978, OBRC member Jeff Gilligan identified a presumed female at the sewage treatment plant (now Fernhill Wetlands) in Forest Grove, Washington County (OBRC "Accepted Records thru 2014"). This bird, the first that was 'chaseable' in the modern era, was a lifer for many Oregon birders who are still active today.

By late winter, an adult male Tufted Duck is pretty unmistakeable. Note the pristine white flanks, jet black back, long wispy tuft feathers, and the curving transition between the white flanks and the black on the back.  This bird was seen along the Columbia River near Portland on 6 April 2013. (Photo by Dave Irons)                

Starting in the early 1980's, Tufted Ducks began to appear with increasing frequency and by turn of the millennium more than 20 accepted records had accrued. The species was removed from Review List in 2001. As one might expect, all but five of the 23 accepted records have involved adult males, which are readily identified by their gleaming white flanks, jet black backs and long wispy feathers trailing from their hindcrowns. All reports of adult males have fallen between 15 January and 8 May, with a decided Feb-Mar spike.

In addition to the aforementioned October 1978 bird,  four additional "females" were found during the years when the OBRC was still reviewing records. These included the first Tufted Duck from east of the Cascades–one at Rufus, Sherman County 5-7 April 1997 (photographed by former OBRC member Craig Miller)–and the only other reports from outside the Jan-May date range. On 22 December 1983 the late Joe Evanich found a presumed female was discovered on Wapato Lake near Gaston, Washington County and a female (presumed returnee from the previous Spring) was back at Rufus 31 Oct-13 Dec 1997 (Nehls 2003).

Since 2000, Tufted Ducks have been found annually in Oregon during late winter and spring. Individual birds often return to the same sites year after year. One male, a presumed migrant as it was never seen during winter, showed up on the same section of an impoundment in the Fisher Unit of Fern Ridge Wildlife Area west of Eugene for at least three successive springs. Similarly, at least one adult male has been among the massive scaup flocks along Marine Drive near the Portland Airport for five years running and a Tufted Duck X Scaup hybrid has been seen along this stretch of the Columbia River for three straight winters. The recent uptick in detections along the Columbia (in both Oregon and Washington) has coincided with a major increase in the numbers of both Greater and Lesser Scaup wintering along the Columbia from the Mid-Columbia Basin in eastern Washington downstream to the mouth.

This Tufted Duck, photographed along the Columbia River near
Portland on 8 December 2012, is still molting. Its dingier
gray flanks might allow it lurk undetected in a large raft of scaup.
(Photo by Dave Irons)

One might wonder why Tufted Ducks are rarely found before mid-January or even later. Part of the explanation may be molt timing. Many North American duck species don't initiate their prebasic molt until mid-to-late fall and it has been shown that their Asian counterparts molt even later, sometimes not starting their head and body molt until December. Thus, while likely present, an adult male Tufted Duck in Oregon during late fall/early winter could easily go unnoticed if it is still in mostly alternate/eclipse plumage. This plumage aspect is cryptic and female-like, with males showing no white on the flanks and little if any evidence of a tuft.

Another identification issue is hybridization. As the number of Tufted Ducks wintering in North America increases, one might expect that the number Tufted Ducks pairing with scaup would increase accordingly. When found, male Tufted Duck X Scaup hybirds lack the long tuft feathers, but do show a short stubby nub coming off the hindcrown. This abbreviated tuft is suggestive of what one sees in illustrations of young or molting male Tufteds. The flanks of such birds may be quite white, but in most photos of putative hybrids, the transition between the dark back and the pale flanks tends to to follow a straighter horizontal line. Finally, the backs on hybrids are not jet black like they appear on a pure adult male Tufted. Instead, the back has a slightly paler and grayer look to it and under close inspection some fine pale gray vermiculations can be seen on the mantle. Here's a link to a nice discussion and some comparative photos of pure male Tufted Ducks and putative hybrid male Tufted Duck X Scaup from Great Britain: http://www.surfbirds.com/community-blogs/amigo/2010/12/03/possible-scaup-x-tufted-hybrid-at-the-haven/. Needless to say, picking out a hybrid female would be a challenge.

Although no longer on the Review List, finding a Tufted Duck in Oregon is still exciting. This species has been found in almost all of western Oregon's counties, but would still be an addition to the list for most counties east of the Cascades. As noted above, late winter through early spring is the best time of year to find a Tufted Duck. They are typically found in the company of scaup, particularly along the Columbia River and on larger bodies of water. There are also a number of records from sewage treatment impoundments and small ponds.

As always, we invite your comments and feedback. Please let us know if you find this sort of review informative and useful.

Sources cited:

Nehls, Harry B. 2003. Tufted Duck. Pp. 112 in Birds of Oregon: A General Reference. D.B. Marshall, M.G. Hunter, and A.L. Contreras, Eds. Oregon State University Press, Corvallis, OR.

An Introduction -- "Under Review: The Oregon Bird Records Committee Online Forum"

By Dave Irons -- OBRC Member

The Oregon Bird Records Committee (OBRC) was formed in 1978. Thirty-six years later our work is still poorly understood, so we are taking a pro-active approach to putting a face on the committee and making our function and processes more transparent. We've decided on this format because of the inherent advantages it provides. Your feedback and questions are essential if we are to maximize our service to the Oregon birding community. Yes, you read that right. We want to better serve Oregon birders.

2014 Oregon Bird Records Committee: Front Row -- Rosalind "Rozi" Finnegan; Middle Row (kneeling) -- Harry Nehls (Secretary), Shawneen Finnegan, Jay Withgott; Back Row (standing) -- Tim Shelmerdine, Tom Crabtree, Tim Janzen, Craig Tumer, Hendrik Herlyn, Jeff Gilligan, Dave Irons, Owen Schmidt. (Photo by Owen Schmidt)

What we do:

Our primary mission is to collect, review, and maintain the records of rare birds found in Oregon. We keep and manage the “Official Checklist of Oregon Birds.” We also keep and manage a “Review List,” which is comprised of those species that are rare in Oregon and those for which we want to collect and archive documentation (photos, video, sound recordings, written descriptions, or specimen records). As a general rule, once 30 accepted records are collected for a rare species, it will be removed from the review list. We follow the taxonomy and nomenclature of the American Ornithologists’ Union (AOU) 1998 Checklist and its subsequent supplements (updated annually). We have an annual meeting every spring, at which we review and update our rules of operation, vote on undecided records that have already gone through two complete rounds of voting, and review digital documentation that is not easily circulated. We publish an annual report in Oregon Birds that lists all of the records that have been processed since the prior year’s annual report.

What we don’t do:

We are not “list police.” While we do create the scorecard (the Official Checklist of Oregon Birds), we have no control, nor do we want control over what an individual birder may or may not put on it. What one counts on a personal life list is ultimately a matter of individual choice. Our “not accept” vote indicates that we find the documentation at hand unconvincing and should not be taken as referendum on the observer’s birding skills or honesty. In reality, there are many times when committee members are confident that the reported species was seen, but find the report to be insufficiently documented.

This forum:

Going forward, this forum will be used to address common questions and concerns about our function and process. We plan to offer feature pieces that focus on individual review species. These will include a review and discussion of the previously accepted records, the patterns (geographic and seasonal) that they may reveal, and identification challenges that they may present. We plan to offer historical perspectives on species that were once on the Review List, but have been removed. We may also discuss species that have been extirpated and/or those that were introduced, but failed to establish or maintain self-sustaining populations in Oregon (i.e. Northern Bobwhite). All of the members and alternates to the committee will be encouraged to contribute to this forum and respond with comments of their own when we hear from you via comments. If there is a topic that you would like to see us address, just ask. We look forward to hearing from you. 

Welcome to the blog of the Oregon Bird Records Committee.

 Our goal is to make our committee work transparent, and to let you know who we are and what we do.