Some thirty years ago I wrote a little paper (in Norwegian) on brown Magpies
(Fauna, Oslo 32, 1979,152-155); a few years later I followed this up with a
similar short paper in Dutch in De Levende Natuur, after brown magpies also had
been noticed in the Netherlands This of course were the 'real magpies', Pica
pica, in the crow family, and not your bell magpies, but I think the phenomenon
will be the same. At the time I figured out that this colour aberration goes
under the formidable name of schizochroic non-eumelanism, i.e. loss of one of
the two melanin pigments that together cause most of the colouring in black
birds. And yes, the condition is hereditary, though probably recessive: a
phenotypically normnal pair produced two brown-and-white and three normal
coloured young. In these Norwegina browmn magpies the feathering seemed
unusually loose, and the birds a bit smaller than normal, so they may well be
at a considerable disadvantage in competition with their normal relatives, so
that the colour form remains rare.
Wim Vader, Tromsø Museum
9037 Tromsø, Norway
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