Sexing Northern Shrikes in the Field?

After reading Dale A. Zimmerman’s (1955) paper on shrike identification, I began to investigate whether Northern Shrikes could be sexed and age-classified (in some cases) in the field. I wasn’t sure at what confidence level sex/age classifications could be attributed while in the field but considered that in some cases, birders reviewing their photographs from the field could analyze their shrike subject further and possibly assign to ‘category’ level. I soon encountered another paper on the subject, this time by Brady et al. (2009), and my interest in the subject piqued even more so.

12592486_10153253697716971_753892122074548725_nFigure 1: A probable adult male Northern Shrike (Lanius excubitor) showcasing an uninterrupted jet black mask (loral region lacking grayish spur or grayish flecking throughout) (Zimmerman 1955); light gray upperparts devoid of any brownish flecking; unmarked, whitish throat; light, crisp barring below (Brady et al. 2009). Photo: Katherine Scott Jarvis. Algonquin Highlands, Haliburton County, Ontario. 4 February 2016.

12696826_10207909218584897_2126145675_oFigure 2: A probable adult male Northern Shrike (Lanius excubitor). This example again showcases the uninterrupted jet black mask (loral region lacking grayish spur or grayish flecking throughout); light gray upperparts devoid of any brownish flecking; unmarked, whitish throat typical of adult males. The under-barring on this individual has been almost completely obliterated by wear/fading, as can occur on late winter/early spring individuals (Pittaway 1999). Photo: Charmaine Anderson. Whitby, Durham Region, Ontario. 10 February 2016.

What I believe to be true at this point in my thinking:

Comments on the content or thoughts from your own field observations are keenly welcomed!

Acknowledgements

Sincere thanks to Katherine Scott Jarvis and Charmaine Anderson for kindly availing the use of their excellent captures of Northern Shrikes. Ryan Brady shared his thoughts and also provided a link to a blog post of his from 2008 which details techniques on ageing shrikes in the field. Thanks also to Marcel Gahbauer for providing helpful feedback pertaining to some vague and potentially misleading terms used in the first installment of this post.

References

Brady, R.S., J.D. Paruk, and A.J. Kern. 2009. Sexing adult Northern Shrikes using DNA, morphometrics, and plumage. Journal of Field Ornithology 80:198205.

Pittaway, R and M. King. 1999. Loggerhead and Northern Shrike ID. OFO News 17(1): 6-7.

Zimmerman, D.A. 1955. Notes on shrike identification and comparative behaviour of shrikes in winter. Wilson Bulletin 67(3): 200-208.