From: ubhjp@sun.rz.tu-clausthal.de (H.-J. Pfeffer)
Subject: Parrots right or left, summary I
Organization: Techn. Univ. Clausthal
X-Newsreader: Tin 1.1 PL5
Date: Mon, 11 Jan 1993 11:50:35 GMT


Handedness (Footedness!) in parrots. Summary Part I                   01/12/93
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Remarks : This survey is based on three calls for data on rec.pets.birds.
          It is published in three parts.
          Part I   contains general results and a short discussion
          Part II  is a list of registered birds in order of scientific names
          Part III is a reference list between scientific and common names
                   of the registered birds.

Results : (% are rounded, I hope I counted out everything correctly)

                              Left-handed        Right-handed
---------------------------|------------------|-------------------------------
male birds   :     24      |  19  = 79.1%     |   5  = 20.9%
female birds :     15      |  10  = 66.6%     |   5  = 33.3%
sex unknown  :     27      |  16  = 59.2%     |  11  = 40.8%
---------------------------|------------------|-------------------------------
total        :     66      |  45  = 68.2%     |  21  = 31.8%

Discussion :             
There were 38 answers to my calls for data. Thanks a lot to all who responded.
Some birds were mentioned only with tendencies to the right or left foot, but
as this is not a scientific survey I put them into the column either right or
left.
The most reported genera were :  
                        Amazona       16 birds   62.5% left-handed
                        Psittacus     12 birds   41.6% left-handed
                        Cacatua        7 birds   85.7% left-handed
                        Nymphicus      7 birds   85.7% left-handed
                        Ara            6 birds   66.6% left-handed
                        Aratinga       6 birds  100.0% left-handed
One bird (Eclectus roratus vosmaeri) had to be omitted because of a damaged
foot. It naturally prefers the other one.
One Brotogeris versicolorus chiriri counted in this statistics with a damaged
foot because it keeps preferring it.
Interesting result : Left-handedness is more dominant in male parrots !
--
There have been earlier surveys on this subject: 
* Friedmann and Davies ("Left-handedness in parrots", Auk, Vol. 55.1938,
pp. 478-480) observed 20 birds of 16 species and found that about 73% were
left-handed. Brotogeris jugularis (Orange-chinned parakeet) even 100%.
Only one bird (Amazona barbadensis) was reported as clear ambidextrous. 
All birds were unsexed.
* McNeil ("Handedness in the Brown-throated Parakeet Aratinga pertinax in 
relation with skeletal asymmetry", Ibis, Vol. 113.1971, pp. 494-499)
examined 28 left-handed and 28 right-handed birds and found that the preferred
foot was slightly longer than the other. (Parts of mm of a certain bone)
It is not clear whether this comes from the preference or vice versa.
* Rogers ("The left and right of brains at work", New Scientist, No. 1651.1989,
pp. 56-59) examined how asymmetry in the brain of chicken influences the 
orientation to one or other side. It seems to be not quite sure if this is
genetically or "programmable" fixed. Parrots are mentioned as mostly
left-handed, but no precise data is given.
--
Thanks again to all who supported this survey, I hope the results were
interesting enough for this newsgroup.
My excuses to all networkers for filling the lines with this stuff.
Any comments and suggestions may be send to : ubhjp@sun.rz.tu-clausthal.de
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H.-J. Pfeffer, Universitaetsbibliothek Clausthal, Germany
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   (I'm not the best in my mother's language, how could I be in English)
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