 There
are barbets in the tropics around the world. Barbets in the Old Word are
here treated as two separate families, Asian Barbets [Megalaimidae] and
African Barbets [Lybiidae]. The African barbets are colorful mid-sized
to small birds of African tropics. Some are well-adapted to the open thornscrub
savanna like this pair of
Red-and-yellow Barbet (left) nicely photographed
by W. Ed Harper. The pair is working on a large termite mound as
this species nests and roosts in such mounds. Red-and-yellow Barbet is
among five species of terrestrial barbets in Africa in the genus Trachyphonus;
this is an old and highly diverged lineage of barbets (more on them below).
They are the most insectivorous of all barbets.
Other African barbets are more like their distant relatives in Asia and South America and are birds of woodlands and forests, moving erratically in search of fruit. Figs are often favored; the Red-fronted Barbet (below) is frequenting such a fruiting fig tree. . |
||||
 There
are 36 species in six genera in Africa of these arboreal birds, including
the tiny tinkerbirds. A mid-sized species is D'Arnoud's Barbet (right)
of east Africa. There is substantial variation in plumage over its range,
and sometimes birds of the southern population, shown here, are split as
a separate species ['Usambiro Barbet'].
Just a couple of decades ago, all barbets around the world were considered to be in one family, and the Toucans were in a different family. But studies of mitochondrial DNA (Lanyon & Hall 1994) and DNA-DNA hybridization (Sibley & Ahlquist 1990) led to proposals that the barbets be separated into three different families: Asian Barbets (Megalaimidae), the African Barbets (Lybiidae), and the American Barbets (Capitonidae, which would include toucans). Recent genetic data (Moyle 2004) support the monophyly of the barbet radiations within each region. To emphasize the close relationships among New World taxa, the three groups there — New World barbets, toucan-barbets, and toucans — were treated as subfamilies of a single family, Ramphastidae, by AOU (1998). This approach means that the Toucans are lost as family and they become just "big-billed barbets." I know that from the perspective of a world birder, toucans are a distinctive group, easily recognized as toucans and nothing else, and that they are exciting birds to see. I like the idea of Toucans as their own family. The Handbook of the Birds of the World (Short & Horne 2002) sticks with the traditional approach of two families: all the barbets (including Toucan-Barbets) in a barbet family and the toucans in a toucan family. That does separate out the Toucans, but misstates their evolutionary relationships. I prefer a more modern approach now taken by the South American Checklist Committee. They split the New World groups into three families (including the distinctive Toucan-Barbets; Barker and Lanyon 2000, Moyle 2004) and have separate families for the Asian and African barbets that are not as closely related. Under this method the two old families (barbets, toucans) become five new families. Use the links below to see the other other four families:
An objection to this arrangement was proposed by Short & Horne (2001,
2002). First, they pointed to the dull Gymnobucco barbets of Africa
and the Brown Barbet Calorhamphus fuliginosus of southeast Asia.
Both groups are dull-colored, lack the vocal repertoire of other barbets,
and nest colonially. Earlier studies had suggested that Brown Barbet might
be linked to the four species in Gymnobucco. Moyle (2004),
however, showed that Gymnobucco proved to be well within the lineage of
African barbets while Brown Barbet was within the lineage of Asian barbets,
and that the similarities shown were a case of convergent evolution. Short
& Horne (2001) also pointed to earlier genetic and cladistic studies
(e.g, Prum 1988, Barker & Lanyon 2000) that showed few links
between Africa's ground-dwelling barbets (genus Trachyponus) and
the rest of the African barbets, and they considered this a "major stumbling
block for those who would recognize three barbet families, one for each
continent," which decision they opined was "decidedly ill-advised." Yet
again, Moyle (2004) removed this "stumbling block." He used three different
molecular methods and undertook three different types of analysis, and
showed flaws in the early studies. A mis-choice of analytical methods (e.g.,
parsimony alone) has the tendency "to unite taxa on long branches even
when not closely related." It appears that the ground-barbets of Africa
are, indeed, related to the other African barbets, and therefore the entire
group evolved on the same lineage from the same ancestor.
|
||||
Many African barbets are birds of open woodlands, acacia scrub, or second-growth.
But there are a number of African barbets, such as the Yellow-billed
Barbet (left), that occur primarily in thick jungle and can be hard
to see. These include such strange creatures as the Naked-faced Barbet
Gymnobucco
calvus or the Bristle-nosed Barbet G. peli of the deep forests
of the Congo Basin and west Africa. Some are particularly gorgeous. The
Double-toothed Barbet Lybius bidentatus, local but widespread across
the middle of Africa, is one of those; it is deep red below. The Yellow-billed
Barbet (photo) is particularly interesting because it is in the same genus
(Trachyphonus) as the ground-barbets. It is primarily a bird of
dense undergrowth, and does feed on the ground on occasion.
All barbets in all three barbet families around the world are hole-nesters.
Those in Asia and the New Word, as well as the African tinkerbirds, excavate
holes in dead trees or stubs. Some African barbets differ in using burrows
in banks or in termite mounds like the Red-and-yellow Barbet shown above.
D'Arnaud's Barbet Trachyphonus darnaudii digs a nearly vertical
tunnel in level ground with a nest chamber at the bottom. The Pied Barbet
Tricholaema
leucomelas sometimes uses the deserted nests of swallows.
|
||||
| One different set of African barbets are the nine small tinkerbirds in the genus Pogoniulus. These are very small tree top birds, often patterned in black-and-white with striped faces and colorful crown patches or rumps. They can be vocal throughout the day but can also be frustratingly difficult to locate. Their calls are often in the background of films set in the African savanna. Among those savanna tinkerbirds in the Red-fronted Tinkerbird (below left). Other tinkerbirds are birds of montane forests, such as the Yellow-rumped Tinkerbird (below right) when in east Africa. Both of these tinkerbird shots are by W. Ed Harper. | ||||
|
||||
| Photos: The pair of Red-and-yellow Barbet
Trachyphonus
erythrocephalus was at Tarangire, Tanzania, on 4 Aug 1994 (photo by
W. Ed Harper). The Red-fronted Barbet
Tricholaema
diademata was eating figs at Lake Baringo, Kenya, 16 Nov 1981. D'Arnoud's
Barbet Trachyponus darnaudii was photographed at Lake
Manyara, Tanzania, in Aug 2002. The
Yellow-billed
Barbet
Trachyphonus purpuratus
was in Kakamega forest, Kenya,
on 18 Nov 1991. Ed Harper photographed both of the tinkerbirds: the Red-fronted
Tinkerbird
Pogoniulus pusillus in Tanzania in August 1994
and the Yellow-rumped Tinkerbird Pogoniulus
bilineatus at Thika, Kenya, in August 1994.
All photos
© 2001 D. Roberson, except those attributed to W. Ed Harper as indicated
and which are © 2001 W. Ed Harper; used here with permission.
Family Book: Rating: I must confess that I don't actually own this book, nor have I done more that quickly glance through it in a bookstore. But every one of the Oxford Univ. Press series on bird families has been excellent, and this looks equally solid. I presume that the "meat" of this book has been summarized by the same authors in their Handbook of the Birds of the World series (Short & Horne 2002) which I do own and have studied.Literature cited: American Ornithologists' Union. 1998. Check-List of North American Birds. 7th ed. A.O.U., Washington, D.C. |
