Long-tailed Shrike’s cross bill

posted in: Morphology-Develop. | 6

An earlier post on the Long-tailed Shrike (Lanius schach) shows the adult with a cross bill, claimed to be a birth defect.

Dr Jeff Lim queried whether this condition was consistent or only momentary, “…say perhaps after preening or beak cleaning? It may not necessarily be a ‘birth defect’ since picture captures a moment in time (although as judged from the image the tip of its beak does exhibit some unusual curvature).” And according to Kennie Pan the photographer, “…the cross bill does not occur all the time…”

To resolve the controversy, Kennie provided his videos (see comments in earlier post) so that images via video grabs could be examined. As shown in all the images posted here, the bill is consistently crossed all the time the bird was in the nest brooding its chick (top left).

Hope this will, once and for all, convince everyone that the Long-tailed Shrike’s bill is permanently crossed, due to a birth defect.

6 Responses

  1. Gim Cheong

    Hi,

    Yes, the bird’s bill is permanently crossed. However, I think that the statement “Hope this will, once and for all, convince everyone that the Long-tailed Shrike’s bill is permanently crossed, due to a birth defect.” is too definitive. Afterall, Wang Luan Keng only suggested that it is “probably a birth defect”

    Bill deformity could be due to many factors, including but not limited to “environmental contaminants, nutritional deficiencies, and disease” (http://alaska.usgs.gov/science/biology/landbirds/beak_deformity/index.html), as well as injury, etc. Let’s keep our minds open.

    Regards.

  2. Agreed! We shall all keep our minds open.

  3. […] such a condition is not as rare as it would appear. So far, we have posted cross bill in Long-tailed Shrike (Lanius schach) and Oriental Pied Hornbill (Anthracoceros […]

  4. I fully agree with Gim Cheong that birdwatchers/bird groups should keep their minds open always. A closed mind will eventually end up into the dustbin of birdwatching history.

  5. BUSSIERE

    Hi,

    I’m a french ringer. Since 2007, I have studied the Red Backed shrike in the Limousin’s region in FRANCE. Last year, i have the opportunity to ring a female with a “funny” beak. This bird has a malformation of the upper mandible. I try to find others examples of beak deformities on shrikes. I found one abnormal bill on Northern shrike in Quebec and your observation. Where (country) did you see this special bird ? have you seen others birds (shrikes) with abnormal beak ?
    Thanks in advance.
    Regards,
    Raphaël BUSSIERE
    FRANCE

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