SHRIKE-BABBLERS & ERPORNIS Pteruthiusidae
- 10 species in south Asia
- DR personal total: 4 species (40%), 1 photo'd
Shrike-Babblers are a small group of south Asian birds, traditionally
considered to be "Babblers" in the old, traditional family Timaliidae.
One example is Green Shrike-Babbler (left).
The old traditional "babbler" family is now split up into five new families [see the new page on the Timaliidae
for details], plus offshoot families of birds that have been proven,
though biochemical research, to be unrelated to babblers; Alström
et al. (2006), Cibois (2003, 2010).
One of those offshoots was once known as "White-bellied Yuhina Y. zantholeuca," but it proved to be most closely related to New World vireos (Cibois 2003, Alström
et al. 2006)! Truly shocking! Now called Erpornis Erpornis zantholeuca,
it is often placed among the Vireonidae. For reasons discussed below, I
chose to place it with the shrike-babblers in this tentative Family.
Then another set of Asian birds, the shrike-vireos (genus Pteruthius),
were also have proven to be related to vireos (Reddy & Cracraft
2007). They do have a unique bill (right; Green Shrike-Babbler again;
all photos on this page). Reddy & Cracraft's analysis, using two
species of shrike-vireos, sequenced two nuclear genes. They found that
shrike-vireos were the sister to a clade that included the North
American vireos and Erpornis. Reddy & Cracraft (2007), followed up
by Reddy (2008), calculated the divergence time of the shrike-babblers
from the remaining Vireonidae at 29.5 million years ago (plus or minus
2.5 million years). We can think of it as about 30 millions years ago.
They also estimated the divergence of Erpornis from the New World
vireos at 23.8 million years ago (plus or minus 2.8 mya).
the standpoint of Family rank, one can view this evidence in four ways:
(1) lump all of them (vireos, Erpornis, shrike-babblers) into one
family (Vireonidae); (2) recognize three families; (3) lump Erpornis
with vireos and split shrike-babblers as a separate family (the
Pteruthiusidae), or (4) place the two Asian genera, both of them early
offshoots of the vireonid line, into a separate family (Pteruthiusidae)
and leave the New World vireos in their own family (Vireonidae). Any of
these three approaches is justified by the current evidence. The first
approach emphasizes the relationships between these groups; the second
approaches emphasizes the long time of divergence between them; the
third approach is a middle ground, emphasizing an evolutionary line
that has been separate from all others for over ~30 million years; and
the fourth is another middle ground, emphasizing the offshoots that
have been separate from vireos for ~24 million years.
the moment, I chose the fourth approach. It seems to me to be the most
consistent with the current approach to Family level taxa. For example,
Beresford et al. (2005) wrote, in reviewing the evolution of a group of
African warblers, that the "basal divergences among Old World warblers
range from 32.3 mya between the Spenoeacus clade and remaining warblers to 31.3 mya between megalurine and other warblers." The Spenoeacus clade mentioned is now widely considered a separate family, the Macrosphenidae [African warblers & crombecs], and the rest of the Old World warblers have been formally broken up into separate families, including the Megaluridae [grassbirds].
If these evolutionary clades are considered Families, having split off
from their nearest relatives ~31 to 32 million years ago, it seems
logical to me that the shrike-babblers — diverging in about that same
time frame at ~30 mya — are better assigned the rank of Family, rather
than Subfamily. While the shrike-babblers and African warblers may be
similar in age, adding Erpornis does not change much of anything. It
diverged ~24 million years, and this approach places the two Asian
offshoots together. Additional research will shed more light on this
So, for the moment, shrike-babblers are
flying at you from your screen as a tentative new family. But do note
the short, rather broad and unusual bill and the large feet. Many
vireos have these same characteristics. In central China, we found that
Green Shrike-Babbler was found in mixed species flocks — which could
include babblers, scimitar-babblers, parrotbills, warblers, and
woodpeckers — but that Green Shrike-Babbler was the "core" species in
the flock. It was the "leader" and the rest of the flock coalesced
around it. Its vocalizations were a way to follow the flock through
thickets and bamboo.
There is yet another
interesting research study on shrike-babblers. Traditionally, most
authorities have listed five species of shrike-babbler.
These five are shown on Hilary Burn's plate in Vol. 12 of the Handbook of the Birds of the World
(right), where shrike-babblers still appear among the old Timaliidae
(Collar & Robson 2007). These are (keyed to numbers on the plate):
- Black-headed Shrike-Babbler P. rufiventer (297)
- White-browed Shrike-Babbler P. flaviscapis (298)
- Green Shrike-Babbler P. xanthochlorus (299)
- Black-eared Shrike-Babbler P. melanotis (300)
- Chestnut-fronted Shrike-Babbler P. aenobarbus (301)
(2008) obtained tissue samples of all five traditional species and most
of the 20+ named subspecies, and undertook molecular phylogenetic
analyses and a systematic review of their morphology and plumage
characters. You can see in the HBW plate that there is much diversity.
As just one example, Green Shrike-Babbler (#299), as traditionally
constituted, there are four named subspecies, two of which lack an
eyering [these are Himalayan populations, illustrated by nominate xanthochlorus on the plate] and two of which have an obvious eyering [these are Chinese populations; pallidus
is illustrated]. It is also apparent from the painting that some
shrike-babblers have strong sexual dimorphism [in contrast, New World
vireos lack sexual dimorphism, so shrike-babblers differ in that way].
(2008) work was an effort to determine the number of species that such
a thorough review might uncover, and she chose to use the Phylogenetic
Species Concept (PSC) for her results. In short, she determined that
the traditional 5 species should be divided into 19 PSC species.
problem with the PSC is that any single unique trait, even one that
lacks any reproductive significance, can be used to "identify" a
species. Many evolutionary biologists deplore the PSC concept when
applied to definitions of species (see Remsen 2005 for a good
overview), and the 'over-splitting' that it engenders can have
significant negative impacts on conservation work.
as to shrike-babblers, Rheindt & Eaton (2009), undertook a thorough
review of Reddy's (2008) work, added vocalizations to the analysis, and
reviewed molecular, morphological, and vocal evidence using the
Biological Species Concept (BSC), which is by far the primary species
concept adopted worldwide. They recommended that the 5 traditional
shrike-babblers be expanded to 9 species, and that one other split is
likely [i.e., between the eye-ringed and unringed Green
Shrike-Babblers] but that evidence from nuclear DNA genetics is needed.
I suspect that the 5 traditional shrike-babblers will become 10
shrike-babblers in due course, but that is still just about half of the
19 "species" proposed by Reddy (2008). It is an interesting topic —
White-bellied Erpornis Erpornis zantholeuca
is the final tentative addition to this new family. It has a wide range
in southeast Asia, from lower elevations in the Himalayas to foothill
forests of the Malaya Peninsula, Borneo, and Taiwan. It is found a wide
variety of open forest habitats, including deciduous forest, secondary
growth, and selectively logged forests (Collar & Robson 2007). Like
shrike-babblers, it often occurs singly or in pairs within
mixed-species flocks. A common behavior while foraging is to hang
upside down, like tits.
|Photos: The Green Shrike-Babbler Pteruthius xanthochlorus was at Foping Nature Reserve, Shaanxi, China, on 12 Nov 2010. All
photos © Don Roberson; all rights reserved.
is no "family book" on the Shrike-Babblers (indeed, I am about the only one assigning them Family rank) but the Handbook of the Birds of the World
account (Collar & Robson 2007) is excellent, with great
photos, although it is not quite up with the most current
taxonomic findings, most of which regarding shrike-babblers postdate its publication.
P., P.G.P. Ericson, U. Olsson, and P. Sundberg. 2006. Phylogeny and
classification of the avian superfamily Sylvioidea. Molecular
Phylogenetics & Evolution 38: 381-397.
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.
Cibois, A. 2003. Mitochondrial DNA phylogeny
of babblers (Timaliidae). Auk 120: 35-54.
A., M. Gelang, and E. Pasquet. 2010. An overview of the babblers and
associated groups. Systematic Notes on Asian Birds 68: 1-5.
Clements, J.F. 1991. Birds of the World: A Check-List. 4th ed. Ibis Publishing, Vista, CA.
Collar, N.J., and C. Robson. 2007. "Babblers (Timaliidae)," pp. 70-291 in Handbook of the Birds of the World (del Hoyo, J., A. Elliott & D.A.
Christie, eds). Vol. 12. Lynx Edicions, Barcelona, Spain.
M., A. Cibois, E. Pasquet, U. Olsson, P. Alström, and P.G.P.
Ericson. 2009. Phylogeny of babblers (Aves, Passeriformes): major
lineages, family limits and classification. Zoologica Scripta 38:
K.A., and J. Fjeldså. 2006. A phylogenetic supertree of oscine
passerine birds. Zoologica Scripta 35: 149-186.
Reddy, S., and J. Cracraft. 2007. Old World Shrike-babblers (Pteruthius) belong with New World Vireos (Vireonidae). Molec. Phylog. Evol. 44: 1352-1357.
Remsen, J.V., Jr. 2005. Pattern, process, and rigor meet classification. Auk 122: 403–413.
F.E., and J.A. Eaton. 2009. Species limits in Pteruthius (Aves:
Corvida) shrike-babblers: a comparison between the Biological and
Phylogenetic Species Concepts. Zootaxa 2301: 29–54.