Babblers

(Timaliidae)

Class: Aves

Order: Passeriformes

Suborder: Passeri (Oscines)

Family: Timaliidae

Thumbnail description
Small to medium-sized birds of highly variable shapes and colors

Size
3–16 in (7.6–40 cm); 0.35–5.25 oz (10–150 g)

Number of genera, species
Roughly 50 genera, around 280 species

Habitat
Generally forests, but some semi-desert, scrub, grassland, and wetlands

Conservation status
Endangered: 5 species; Vulnerable: 22 species; Near Threatened: 39 species; Data Deficient: 1 species

Distribution
Eurasia (excluding Japan), Wallacia, Africa, Madagascar, the Pacific Coast of North America (Introduced in Hawaii)

Evolution and systematics

Nearly a century ago, Ernst Hartert, Curator of the incredible Rothschild collection of preserved birds, observed: "What can't be classified is regarded as a babbling thrush." In the opinions of many of today's ornithologists, Hartert then proceeded to confuse matters further. The convoluted history of babbler classification is well treated in Sibley and Ahlquist's Phylogeny and Classification of Birds, and the reader is best referred to that book. Suffice it to say that exactly what a babbler is, and how it should be classified, has been, and remains, a controversy among ornithologists.

Jean Delacour's masterful arrangement of babblers, proposed in the 1940s and 1950s, has worked remarkably well, even as 1980s experiments in DNA-hybridization completely reorganized bird classification, and the rationale behind it. Delacour considered the babblers a vast subfamily, Timaliinae, one among many in the huge family Muscicapidae, created by Hartert in 1910, and now determined to be a hodgepodge of unrelated birds. Delacour divided his Timaliinae into a series of tribes, including one for both the wrentit (Chamaea) and bearded reedling (Panurus), both of which were traditionally placed in different families. He also gave tribe status within the babblers to the parrotbills (Paradoxornis and Conostoma) and to the genus Picathartes. Picathartes had long been especially controversial, being assigned to the starling and crow families by various authorities.

The DNA research of Charles Sibley and his associates has led them to place the babblers in the family Sylviidae, together with many of the birds traditionally called Old World warblers. Within this family, they have divided the babblers into two subfamilies. Two genera, the laughing thrushes (Garrulax) and liocichlas (Liocichla), are given their own subfamily, Garrulacinae. The other babblers, including the parrotbills, which have traditionally been placed in a subfamily, Paradox-ornithinae (or Panurinae), are included by Sibley in the sub-family Sylviinae, divided into three tribes. All but one of these are in the tribe Timaliini, the exception being the wrentit, comprising its own tribe, Chamaeini. The third tribe, Sylviini, consists of the warblers of the genus Sylvia, including such familiar European birds as the blackcap, whitethroats, and the garden warbler. One controversial inclusion in the tribe Timaliini, as Sibley defines it, is the genus Rhabdornis, the Philippine creepers, traditionally placed near the nuthatches and creepers. On the other hand, the genera Pomatostomus and Garritornis, considered by Delacour and others to be close relatives of the scimitar babblers, now constitute their own family, Pomatostomidae, which Sibley and colleagues placed near the crow family, Corvidae. The rail babblers (Eupetes and Ptilorrhoa), which Delacour initially assigned to a tribe within the Timaliinae, then later considered a separate subfamily, are classified by Sibley as a subfamily within the Corvidae. It is not surprising that Sibley removed Picathartes, long a source of disagreement, from the Timaliinae, nor is his refusal to place their family in close proximity to any other. What is truly startling is his inclusion, in the family Picathartidae, of the rock jumpers (Chaetops), traditionally classified as thrushes (Turdidae).

Paleontology has, thus far, not served to clarify the origins and relationships of babblers, the only fossils being a Middle Pleistocene example of the modern species, the Arabian babbler (Turdoides squamiceps). DNA research seems to support Asian origins in the Oligocene, about 40 million years ago.

Physical characteristics

Almost any book published over the last 50 years is likely to present a different definition of exactly what constitutes "the babblers." Over 40 years ago, Oliver Austin, in his now classic Birds of the World, summed up the situation by describing this group as "poorly defined and loosely delimited." All of these birds have 10 primary feathers, the outermost shorter than the rest. The tail is composed of 12 retrices. The plumage is soft and loose. Juvenal plumage is never speckled. The legs and feet are proportionately large and powerful, while flight potential is comparatively small (leading, in part, to the great number of species with small ranges). In appearance babblers range from the utterly nondescript to the unforgettable.

Despite the great disagreements among most books, one usually finds the babblers arranged thusly. To begin with are several genera of "small brown birds," otherwise referred to as "somber," "dull" or "nondescript." Often their most recognizable feature, at least when they're alive, are their voices. The number of genera is in dispute, but a few more than 30 species compose these "jungle-babblers" (Pellorneum, Trichastoma, Illadopsis, Kakamega, Malacopteron, etc.), all of them tropical, most of them forest-dwellers, occurring through large areas of Africa and Asia. There follow around a dozen scimitar babblers (Pomatorhinus, Xiphirhynchus, and Jaboulleia), named for their long curved bills, some quite spectacular. They appear to be closely related to the around 20 very different-looking wren-babblers (Rimator, Ptilocichla, Napothera, Pnoepyga, Spelaeornis, etc.). These are short-tailed, mostly plump-bodied birds, some tiny, none with brilliant colors, but some with vivid patterns. Some strongly resemble New World antbirds. Scimitar babblers and wren-babblers are Asian, with one species extending down the Lesser Sundas to Timor. What comes next depends on the book one is reading, and here things may differ wildly. Suffice to say that there follows the majority of the babblers, in many genera great and small. Towards the end, one usually finds the parrotbills (Paradoxornis and Conostoma) of Palearctic and Oriental Asia, and the primarily Palearctic bearded reedling (Panurus biarmicus), mostly compact-bodied and long-tailed, many with distinctive bills, one, (Paradoxornis paradoxus), uniquely with three toes instead of four. Finally, one may or may not find the unique and magnificent Picathartes. What they are remains a question.

Distribution

Asia is the center of evolution for babblers. With the exception of the unique picathartes, which DNA research suggests may not be babblers at all, but an ancient African lineage, most of the 33 African babblers appear to be derivative of large Asian genera. Only recently have several of them been removed from Asian genera, and placed in ones exclusive to Africa, such as Illadopsis and Pseudoalcippe, while 15 are clearly members of Turdoides, widespread in the Indian subcontinent. Typical of the island, the six species in Madagascar, all endemic, have no connection to the African mainland.

China, where the Palearctic and Oriental zoogeographical realms meet, is a great center of distribution, and at least 143 (including four Taiwanese endemics) occur there, many nowhere else. Chinese babblers include 35 of the 49 species of laughing thrushes (Garrulax), 14 of the 16 fulvettas (Alcippe), and every one of the 19 parrotbills (Paradoxornithinae). Through Southeast Asia, there continues a great diversity of babblers, especially in Indochina, where several were only recently discovered. Fifty-five species have been recorded for Java, Sumatra, and Borneo, many of them endemic, or otherwise found only on the Malay Peninsula. While the "babblers" inhabiting Australia and New Guinea are no longer considered Timaliids, a few species occur in Wallacea, including the enigmatic malia (Malia grata), found only on Sulawesi, and remarkably, the fragile-looking pygmy wren-babbler (Pnoepyga pusilla), found all the way from Nepal to Timor. It is remarkable that Japan and Okinawa have no native babblers. On the other hand, 19 species occur in the Philippines, including 10 of the 24 species of Stachyris, and all but one are endemic. The Philippines and Timor are the western-most of the Pacific islands where babblers occur naturally. (Four Asian species have been successfully introduced in Hawaii.)

The Indian subcontinent, including Sri Lanka, is another babbler stronghold, and 131 species are recorded there. The majority are birds of the Himalayas, shared with China, but a number are endemic to Peninsular India or Sri Lanka. In the Middle East, babblers are represented by three species of Turdoides. Europe, including the United Kingdom, share the bearded reedling (Panurus biarmicus) with temperate Asia. Finally, on the Pacific Coast of North America is the wrentit (Chamaea fasciata).

Habitat

Forests are the stronghold of babblers, and most are dependent on one type or another. However, natural selection being what it is, there are babblers adapted to scrublands, near-desert, grassy savannas, and marshes, and some species have become partial to orchards, fields, and gardens.

Behavior

For so diverse a group of birds, generalizations are difficult. As did Bertram Smythies in the first edition of this encyclopedia, one cannot do better than to quote Jean Delacour, from his monumental 1946 monograph of the babblers: "They move restlessly among twigs and on the ground; they hop about and dig among fallen leaves. Usually they live in the undergrowth, sometimes on the ground among dense plant growth, fallen branches, climbers and evergreen trees, where they can be observed searching for berries and insects. While doing so, they move busily, flutter the wings a great deal, wag their tails and utter noisy calls. As rule, they are loud and varied vocally, hence the name babbler, for they are virtually never quiet. Some sing very well and their full melodies ring out far. Outside the breeding season, they move about in small troops. Often they join with other birds into the mixed flocks characteristic of tropical forest, all seeking food together."

Delacour's description fits most of the forest-dwelling babblers fairly well. It is in other sorts of habitat that particularly interesting variations have evolved. The Arabian babbler (Turdoides squamiceps), of the semi-desert, with its highly developed "tribal" social system, and the semi-aquatic bearded reedling (Panurus biarmicus) of the marshes, are two striking examples.

Feeding ecology and diet

Insects are the core of babbler diets. Some species appear to feed exclusively on them, while many also eat fruit, other invertebrates, and small frogs and reptiles. As with any huge family, there have evolved some peculiar specialists. While the bearded reedling feeds vigorously on insects for most of the year, and rears its young entirely on them, it subsists on seeds during the winter, its digestive tract making remarkable adjustments to this change in diet. As one might expect, the desert-adapted Arabian babbler will eat practically anything. On the other hand, the fire-tailed myzornis (Myzornis pyyrhoura) has come to resemble a hummingbird or sunbird, consuming nectar with its insects, and becoming a pollinator in the process.

Reproductive biology

In general, babblers form pairs in the breeding season, establish territories, raise one or two broods, then reassemble as flocks. Again, this seems to be the case for forest species, with most exceptions being birds of other habitat. The bearded reedling has evolved to produce up to four broods in quick succession each breeding season, with the first potentially able to breed themselves by season's end. The Arabian babbler's reproductive system, however, is remarkably different. Its highly regimented social units, with birds waiting as long as six years for their first opportunity to breed, is only the most extreme situation in its large and widespread genus Turdoides. Researchers have confirmed that at least 14, and possibly 26, of the 29 species in this genus practice some sort of cooperative breeding, with groups defending territories where only a few members will breed at any given time. The Turdoides are primarily open-country birds. In India, the tendency to always remain in their social unit has earned some species the name "Seven Sisters," and India's revered ornithologist Salim Ali refers to their groups as "sisterhoods." Another departure from the norm are the colonial picathartes, who use their unique, mud pottery-like nests, built on rock faces, as residences, and raise chicks in them year after year. Such nests are unique among babblers, who, in general, construct cup or bowl-shaped, or spherical, nests of plant materials, usually not far from the ground. Eggs run a spectrum from white and patternless, to various beautiful colors and intricate patterns of spots and streaks.

Conservation status

As of 2002, the IUCN and BirdLife International designated five babblers as Endangered, 22 as Vulnerable, and 39 as Near Threatened. In addition, it appears that subspecies of two otherwise globally non-threatened species may be extinct: The southern Turkish bearded reedling (Panurus biarmicus kosswigi) appears to have been a victim of wetlands destruction, while the mysterious "Astley's leiothrix" (Leiothrix lutea astleyi), known only from the bird trade more than 80 years ago, may have been exterminated through trapping.

All five Endangered babblers are primarily threatened by habitat loss. All are forest birds. Two are Philippine endemics: the flame-templed babbler (Stachyris speciosa) occurs only on Negros and Panay, while the Negros striped-babbler (S. negrorum) is entirely restricted to that severely deforested island. The remaining three depend on high-elevation forests: the Nilgiri laughing thrush (Garrulax cachinnnans), one of many imperiled inhabitants of India's Nilgiri Hills, the white-throated mountain babbler (Kupeornis gilberti), known to science only since 1949, restricted to several places in Nigeria and Cameroon, and the gray-crowned crocias (Crocias lang-bianis), rediscovered in 1994 after 56 years of no records, from a few locations in Vietnam.

Three Vulnerable species, the Omei Shan liocichla (Liocichla omeiensis), found only around Mt. Emei, in southwestern China, and the white-necked and gray-necked picathartes (Picathartes gymnocephalus and P. oreas), of the Guinea forests of West Africa, were vigorously exploited by the cage-bird trade, resulting in their listing by the Convention on International Trade in Endangered Species (CITES). Like the 19 other Vulnerable babblers, they are threatened by habitat destruction as well.

Fourteen island endemics, seven restricted to the Philippines, are included among the 39 Near Threatened species, and of the remainder, nine occur only in the Malay Peninsula, Sumatra, and Borneo. Again, loss of habitat, in often restricted ranges, is the cause for their designation. Finally, there is one categorized as Data Deficient, the miniature titbabbler (Micromacronus leytensis), at 3 in (7.6 cm), the smallest babbler. Restricted to the Philippine islands of Leyte, Samar, and Mindanao, it is a forest-dependent species in a land of increasing deforestation, and has remained rare, and little known since its discovery in 1961.

Significance to humans

Babblers have long been admired for their appearance, songs, and behavior. One aspect of this admiration has been the compulsion to keep them in captivity. The enormous volume of commercial trade in living babblers has caused increasing concern. At the same time, over 30 species have been hatched in captivity.

Some Chinese babblers, especially laughing thrushes (Garrulax sp.) and parrotbills (Paradoxornis sp.) cause some damage to crops, but this appears to be minor, and offset by insect control by these same birds. On the other hand, babblers are playing an increasingly important role in the developing economy of ecotourism. Such species as the fire-tailed myzornis are specifically featured in advertisements enticing trekkers to Nepal and Bhutan, already attracted simply by the potential of seeing great numbers of species in the foraging "bird waves" that sweep across the Himalayas. As ecotourism continues to grow, increasing numbers of people from around the world will enjoy the magnificent mixed choruses of otherwise unobtrusive brown babblers in Borneo or Myanmar, search for Madagascar's peculiar endemics, observe the colonial nesting of fantastic-looking picathartes in Ghana or Gabon, and search for laughing thrushes only recently unknown to science in the highlands of Vietnam. At the same time, vigorous efforts are being made by environmentalists in these countries to instill pride in a precious natural heritage.

Species accounts

Resources

Ali, S. The Book of Indian Birds. New York: Oxford University Press, 1996.

Collar, N. J., A. V. Andreev, S. Chan, M. J. Crosby, S. Subramanya, and J. A. Tobias. Threatened Birds of Asia. Barcelona and Cambridge: Lynx Edicions and BirdLife International, 2001.

Cramp, S., C. M. Perrins, and D. J. Brooks, eds. Handbook of the Birds of Europe, the Middle East, and North Africa, Vol. 7. New York: Oxford University Press, 1993.

Fry, C. H., S. Keith, and E. K. Urban, eds. The Birds of Africa, Vol. 6. London: Academic Press, 2000.

Kennedy, R. S., P. C. Gonzales, E. C., Dickinson, H. C. Miranda, and T. H. Fisher. A Guide to the Birds of the Philippines. New York: Oxford University Press, 2000.

MacKinnon, J. R., K. Phillipps, and Fen-qi He. A Field Guide to the Birds of China. New York: Oxford University Press, 2000.

Morris, P., and F. Hawkins. Birds of Madagascar. New Haven and London: Yale University Press, 1998.

Sibley, C. G., and B. L. Monroe. Distribution and Taxonomy of Birds of the World. New Haven and London: Yale University Press, 1990.

Sibley, C. G., and J. E. Ahlquist. Phylogeny and Classification of Birds: A Study in Molecular Evolution. New Haven and London: Yale University Press, 1990.

Eames, J. C. "On the Trail of Vietnam's Endemic Babblers." Oriental Bird Club Bulletin 33 (June 2001): 20–26.

Lindholm, J. H. "The Laughing Thrushes." A.F.A. Watchbird 24 (January/February and March/April 1997): 42–47, 53–58.

African Bird Club. . (29 March 2002).

International Species Inventory System.. (29 March 2002).

Oriental Bird Club.. (29 March 2002).

[Article by: Josef Harold Lindholm, III, BA]