You are correct in saying it's a White-bellied Cuckoo-shrike. This is not a
hybrid, it is a straight out adult White-bellied Cuckoo-shrike. Below is what I
found when I investigated this species, when writing the Field Identification
text for HANZAB.
In SE White-bellied Cuckoo-shrikes vary considerably. There is the typical
light morph, & there are the darkest birds, when can be very dark,
black-hooded, darker grey above & barred below; these aren't straight morphs,
in between there is every kind of variation, they start from a few dark
feathers in the ear-coverts, to patchy black head. One of the variations (as
I've seen in skins) is a lot like an adult BFCS, plumage wise they tend to have
a few odd black feathers outside the hood, on the upper breast or crown. I find
there are characters that always separate WBCS from BFCS: (1) WBCS has a
proportionately shorter, more compact stubbier bill (longer in BFCS). (2) WBCS
is distinctly smaller, to be sure of this there has to be some comparison, for
example if the bird in question is with other WBCSs then it should be about the
same size; beware, it is very easy to get the size wrong in the field. (3) One
other classic feature is very obvious in your photo, WBCS has much broa
der white edges to it's tertials & secondaries. (4) You are quite correct
about the paler crescent behind the eye, this is never present on adult BFCS,
however be careful it may not be present on all WBCS in this type of plumage.
Hope this helps-Kevin Bartram
> Date: Mon, 17 Jun 2013 17:21:46 +1000
> Subject: [Birding-Aus] Strange Cuckoo-shrike
> Hello all.
> This morning I was at Sheepstation Creek Conservation Park near Caboolture
> in Queensland. Both White-bellied and Black-faced Cuckoo-shrikes are common
> here, and they are normally fairly easy to distinguish. One bird, however,
> had me puzzled. At first I thought it was a regulation BFCS, but on closer
> inspection it was more the size of a WBCS, has light half eye-ring (a
> feature of WBCS), and, even though it has a darker area the shape of that of
> a BFCS, if you look closely you can see a slightly darker facial mask area.
> The bill looks too small for BFCS. Now, I realise there are dark morphs of
> WBCS (which I've never seen), but I have only ever seen photos of birds with
> a totally dark head. So, I have three questions:
> 1. Do dark morph WBCS have gradations, or are they either all or
> 2. Do BFCS hybridise with WBCS?
> 3. Have I been duped by a juvenile?
> A rather ordinary photo is here: http://www.pbase.com/image/150836159
> Cheers Steve Murray
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