Magpie back colour is not a simple matter. In the attached I have snapped the magpie family in my street, two adults, two juvs. All in my view are, albeit slightly for 3 of them, of hybrid plumage type. A difficulty
is that the full back is concealed by folded wings. In Stan’s photo at B it is not possible (not for me anyway) to say whether the bird has a largely white lower back or whether the white shown is a merging of the white patches of the folded wings. On the
other hand, my adult male at A clearly has soft white feathers of the mantle overlaying the wing feathers. Juvenile C has more extensive greyish white.
Looking at the magpie photos in the Cornell Lab Macaulay Library makes you aware of the problem. I began a count of plumage types for the 1,653 for the ACT. The ones showing little or no back were quickly discarded.
A difficulty with possible black-backed types is that the full back is rarely shown. I got to 10 definite black-backs. My number for those where there was sufficient to suggest a probable black-back is 121. I should say I gave up after sifting through several
hundred when I lost my place. The hybrid types were identifiable where there was an enlarged nape-patch or any white below the nape. I counted 51. I do not offer these results as a representative cross-section because some contributors might have submitted
their photo of this common species only because they thought it showed unusual colour. One hopes museum collections are not affected by the same bias.
