[CT Birds] Odd Characteristic of Hudsonian Godwit

Chris Elphick elphick at sbcglobal.net
Tue Oct 20 05:19:10 EDT 2009

Hi Don

Many birds have "kinetic" zones along their bills allowing them to bend their beaks like the godwit you photographed.  Most common (as I recall; this is really Margaret Rubega's area of expertize) is a zone at the point where the maxilla meets the skull at the base of the bill (the maxilla is the upper jaw, which birders refer to as the "upper mandible", though strictly (anatomically) speaking the mandible is the lower jaw, and "upper mandible" just means the top side of the lower jaw).  This is most commonly observed in parrots, but occurs in various other species.

In some species - e.g., shorebirds, hummingbirds - there are several flexible zones along the length of the bill, including one at the tip as shown in your picture.  I've seen this most commonly in longer-billed species - resting dowitchers quite regularly flex open their bill tips in the same manner - but it may just be that it is more obvious in these species.   Margaret's former student who did a lot of high-speed video work with hummingbirds also has film of it in various hummers (I think Mark Szantyr has a really good photo too).

Exactly what the flexion is used for - or how, mechanically they do it, is not known, but it probably helps shorebirds to grab worms, etc. when probing in the mud.  Shorebirds also have a lot of touch sensors in their bill tips.  Among other things, these allow them to assess pressure differentials in the mud, which helps them detect prey items.  

Hope this helps,


Chris Elphick

Storrs, CT

elphick at sbcglobal.net

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