Friday 16 January 2015

White-browed Coucal x Burchell's Coucal intergrades

White-browed Coucal intergrade (White-browed Coucal x Burchell's Coucal), Liwonde (Malawi), 23rd September 2008 - copyright Dave Appleton
(photo ID: 1771)

Burchell's Coucal is quite a different-looking beast from White-browed Coucal and have often been treated as different species.  However there is significant intergradation between the two taxa and many authorities now treat them as the same species.

In Malawi Burchell's Coucals (race burchellii) occur in the south and one of the forms of White-browed Coucal (race loandae) occur in the far north.  In between birds intergrade.  On my visits I mainly saw birds in the south, just inside the range of burchellii, however one of these birds showed a few pale streaks in the black of the head and neck and also on the scapulars.  Such streaking is not present on pure burchellii so I assume this was an intergrade, albeit much closer to Burchell's in appearance than the northern forms.  I saw a more obvious intergrade further north but didn't manage to get any photos of that bird.

White-browed Coucal Centropus superciliosus
White-browed Coucal Centropus (superciliosus) superciliosus/sokotrae/loandae
Burchell's Coucal Centropus (superciliosus) burchellii/fasciipygialis

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