 The
Helmet-Shrikes are a small group of mostly African birds, although apparently
an ancestral helmet-shrike reached Asia as it is currently thought a few
Oriental species are closely related. The Helmet-shrikes are closely related
to Bush-Shrikes (Malaconotidae), Vangas (Vangidae), and the Batises &
Wattle-eyes (Platysteiridae). Indeed, most of the older literature lumps
this group with one or more of these families. The relationships of the
Helmet-Shrikes with closely related groups are just now being sorted out
by DNA sequencing (Fuchs et al. 2004).
The typical Prionops helmet-shrikes, like the White Helmet-shrike
(left), are noisy sociable birds, restlessly traveling through bush or
woodland in parties of a few to two dozen individuals. The feed mainly
among branches and foliage, and I had to grab this shot quickly as they
were constantly moving on. Some of the species breed co-operatively and
roost communally.
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 Some
species have a circular fleshy wattle around the eye, and an example is
shown by the Chestnut-fronted Helmet-shrike (right) of coastal east
Africa. It is often found it flocks with other birds, acting tit-like as
it forages along branches or clings to trunks. The eye-wattle recalls the
unique African wattle-eyes which are placed (at least by ) in a separate
family, along with batises and a few other odds-and-ends, the Platysteiridae
(Zimmerman et al. 1996; this proved to be correct, Fuchs et al. 2004).
Earlier workers (e.g., Dowsett & Dowsett-Lemaire 1993), lumped the
helmet-shrikes and bush-shrikes with the world's regular shrikes in the
Laniidae, but this proved to be erroneous (Barker et al. 2004, Fuchs et
al. 2004).
Among the 8 Prionops helmet-shrikes, two are rare enough to be
classified as threatened. The obscure Gabela Helmet-shrike P. gabela,
known only from a small area of forest & thicket near Gabela on the
scarp of Angola, is considered Endangered. Yellow-crested Helmet-Shrike
P.
alberti is a real enigma of the mountains of eastern Congo. Almost
nothing is known about this spectacular bird that appears on my "top 50"
best birds of the world (a small painting of Yellow-crested Helmet-Shrike
is below).
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 All
of the Prionops species have striking plumage patterns (often black-and-white),
and many have colorful bills or eye-wattles. Looking at field guides, I
always wanted to see Retz's Helmet-Shrike because it looked so cool. This
past summer we got to see a pair at Xaro Camp on the Okavango River in
northern Botswana. Retz's Helmet-Shrike (left) is indeed a classy
bird.
The taxonomic position of helmet-shrikes has long been the subject of
debate, with widely different approaches (e.g., Traylor 1986, Sibley &
Ahlquist 1990, Sibley & Monroe 1990, Keith 1992, Dowsett & Dowsett-Lemaire
1993, Dickinson 2003). However, much of the debate was settled recently
when DNA sequencing data became available for most of the species in this
and related families (Fuchs et al. 2004). It shows that among the bush-shrike,
helmet-shrike, vanga, batises, wattle-eyes, and shrike-flycatchers, there
are three distinctive clades: (a) the core bush-shrikes, (b) the batises
and wattle-eyes, and (c) the rest of them. Thus helmet-shrikes, vangas,
and shrike-flycatchers are all on the same evolutionary branch. One approach
would be to lump them all in a single family. But many authors (e.g., Dickinson
2003) consider the vangas to be a separate family that arose in Madagascar.
If we split those out, the remaining species are left in the Prionopidae.
Further research will likely refine this situation, but there we are for
today.
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 Of
the three species of 'shrike-flycatcherss' in Africa and Madagascar, recent
DNA research has shown that Ward's Flycatcher Pseudobias wardi,
the Madagascar bird, is a flycatcher-like vanga (e.g., Schulenberg 2003).
This leaves just two African 'shrike-flycatchers' within the Helmet-shrikes:
the widespread but patchily distributed Black-and-white Shrike-Flycatcher
Bias
musicus, and the African Shrike-Flycatcher Megabyas flammulatus
of western and central African forests. Bias and Megabyas
had been put in with the Platysteiridae by Dickinson (2004) but it appears
they are better placed here.
Then there is the problem of some Asian enigmas: the two species of
woodshrikes (Tephrodornis) and the two species of philentomas (Philentoma).
Woodshrikes are rather like small bush-shrikes that live in the woodlands
from India through southeast Asia to the Greater Sundas. A Common Woodshrike
(right) is shown in this shot from India; it is a common species found
even in light woodland in urbanized areas. Rufous-winged Philentoma P.
pyrhoptera and Maroon-breasted Philentoma P. velata look like
mid-sized sturdy flycatchers in the forests of southeast Asia and the Greater
Sundas. These groups have long been mysterious as to origin, and have been
placed with such disparate families as cuckoo-shrikes, Old World flycatchers,
and ioras. Dickinson (2003) holds them in "Incertae Sedis" among all the
bush-shrike families. No one appears to have yet published a recent biochemical
analysis of the situation, but for the moment it seems that they (like
the shrike-flycatchers) might be most closely related to vangas or to helmet-shrikes.
Accordingly, we place them here for the moment, a position that is in accord
with Harris & Franklin's (2000) review of all these groups.
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| Photos: The White Helmet-shrike
Prionops
plumatus was photographed in Kruger Nat'l Park, South Africa, on 28
July 1996. The Chestnut-fronted Helmet-shrike P.
scopifrons was in the Sokeke Forest of coastal Kenya, 28 Nov 1981.
Kim Franklin painted the Yellow-crested Helmet-Shrike; from Shrikes
& Bush-Shrikes (2000) by Tony Harris (Princeton Univ. Press). The
Retz's Helmet-shrike Prionops retzii was at Xaro Lodge
in northern Botswana on 23 July 2005. The Common
Woodshrike Tephrodornis pondicerianus was at Sultanpur
Jheel, Haranya, India, on 11 Mar 2001. All photos
© D. Roberson 2005; all rights reserved.
Bibliographic note: Family book: Rating This is a very attractive offering in the Princeton bird families series. Tony Harris wrote the text; Kim Franklin did the plates. It has the familiar layout of plates altogether in the front, with range maps and i.d. summary, and detailed species accounts in the back. It looks well researched and has a good bibliography. I very much enjoyed the full-page spreads, with black-and-white sketch, on each genus in the groups covered, that highlights the introduction. There is a lot of discussion of taxonomy but, unfortunately, the authors chose to follow the Sibley & Monroe (1990) approach of only two families: shrikes [Laniidae] and bush-shrikes [Malaconotidae]. All of the batises, wattle-eyes, helmet shrikes, and such things as flycatcher-shrikes, wood-shrikes, and philentomas, are thrown into the latter family. New research does not support this approach. As it turns out, the true shrikes are not the closest relatives to the rest of this set (e.g., Barker et al. 2004), so even the premise of this book proves false. Further, vangas (not included in this book) are closely related to the rest of the group. Indeed, it appears that the flycatcher-shrikes are vangas, and that helmet-shrikes are very closely related to vangas. The text also suffers from the author's use of the "Species Recognition Concept" as his definition for species; fortunately, in practice, in works rather like the tried-and-true "Biological Species Concept." Yet both in its language and in its reliance on DNA hybridization evidence (Sibley & Ahlquist 1990), this book has the unfortunate status of being out-of-date taxonomically much more quickly than would be anticipated.
Barker, F.K., A. Cibois, P. Schikler, J. Feinstein, and J. Cracraft. 2004. Phylogeny and diversification of the largest avian radiation. Proc. Nat. Acad. Sci. 101: 11040-11045. |
