[Tweeters] crossbill question

Kenneth Trease krtrease at gmail.com
Tue Mar 24 14:36:11 PDT 2015


Gary,
Someone has probably already sent you this link but just in case check the
section under "Feeding Behavior."

http://en.wikipedia.org/wiki/Crossbill

On Mon, Mar 23, 2015 at 10:21 PM, lsr at ramoslink.info <lsr at ramoslink.info>
wrote:


> Garuy,

>

> According to BNA:

> Bill distinctive, with mandibles curved and crossing at tip. Lower

> mandible crosses to right as often as to left.

>

>

> Scott Ramos

> Seattle

>

>

> ------------------------------

> *From*: "Gary Bletsch" <garybletsch at yahoo.com>

> *Sent*: Monday, March 23, 2015 9:00 PM

> *To*: "Tweeters Tweeters" <tweeters at u.washington.edu>

> *Subject*: [Tweeters] crossbill question

>

> Dear Tweeters,

>

> It occurred to me today that I did not know the direction of the curvature

> of the bill of a crossbill. I looked at some pictures on the Internet, and

> saw some variation. With these images, I figured there might be some photos

> that had been reversed according to the photographer's whim, perhaps.

>

> The pictures in my copy of Big Sibley show the top mandible going to the

> bird's right, in both of our species of crossbills.

>

> The pictures in Lars Jonsson's *Birds of Europe with North Africa and the

> Middle East *appear to show the top mandible going to the left on a male

> Red Crossbill, but the top mandible going to the right on the female. This

> book shows a male Parrot Crossbill with the top mandible going to the

> right, with the female's top mandible going left. Then it shows the

> White-winged Crossbill female's top mandible going right. I couldn't tell

> what Jonsson was showing on the male White-wing, because the bird is

> depicted with bill open, attacking a cone.

>

> I had always assumed that crossbills had the same sort of chirality as

> that seen in the various species of flatfishes, where the "handedness" was

> always the same in a given species, barring rare mutations.

>

> How does this work in crossbills?

>

> Yours truly,

>

> Gary Bletsch

>

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>

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