Working for birds in Africa

Toucans, Barbets and Honeyguides

Fri, 12/21/2012 - 13:47 -- abc_admin
Lester Short and Jennifer Horne, illustrated by Albert Earl Gilbert, 2001, 526 pp, 36 colour plates, 17 colour photographs, 132 distribution maps. Oxford: Oxford University Press. ISBN 0-19-854666-1. UK£60
pages 40 - 41

This, the eighth volume in the Bird Families of the World series, covers three of the four families in the order Piciformes (the fourth being the woodpeckers) by two ornithologists who have a long-standing reputation of being the experts on the subject. Like its predecessors in the series, the book is divided in two parts. The first (112 pp) includes chapters on evolutionary relationships, distribution, habitats, morphology, behaviour, breeding biology and other aspects of the birds' life cycle. These are written in a colloquial style, devoid of jargon, and enlivened by some line drawings and black-and-white photographs depicting special features and aspects of behaviour. The photographs are rather dark but colour versions are, very usefully, reproduced in the colour plate section. One chapter is entirely devoted to the unique behaviourial ecology of the wax eating and brood parasitic honeyguides. The second part, the bulk of the book, contains the species accounts, ranging in length from one to seven pages per species (usually 2-3 pp) and including a distribution map. All species are illustrated in 36 colour plates. Twenty-nine pages of references, updated until 1997, attest to the authors' thoroughness.

Of the 133 species treated, 56 occur in the ABC region: 41 barbets (exactly half of the total of 82) and 15 (of the 17) honeyguides (the toucans, with which we will not concern ourselves here, number 34 species). Seven of the 13 barbet genera are Afrotropical, compared to three genera each from tropical Asia and America. The barbets have sometimes been split into three families, one for each of the continents on which they occur, with Afrotropical species grouped in Lybiidae (cf. Sibley & Monroe). This, however, is considered ill-advised by Short and Home, as there is no evidence that any geographical grouping would link closest relatives. Compared with the treatment of barbets and honeyguides, by the same researchers, in Birds of Africa (BoA), there are no taxonomic changes, although the sequence in both families is different. Thus, instead of being last, the Trachyphonus barbets are now placed first, before Gymnobucco, whereas Lyre-tailed Honeyguide is now placed at the end of its family, after the Indicator species, the order of which has been reversed, with small species appearing first and Greater Honeyguide last.

The forest-dwelling Yellow-billed Barbet is maintained in Trachyphonus, although authorities such as Bannerman, Bates, Chapin and Mackworth-Praed & Grant included it within the monospecific Trachylaemus, to differentiate it from open country social species in Trachyphonus, which differ from it in plumage, behaviour and vocalisations, a treatment that has been followed by recent Western and East African identification guides. According to Short and Home, however, it is connected with the ground barbets by Crested Barbet T. vaillantii, which they consider to be intermediate. Lesser Indicator minor and Thick-billed Honeyguides I. conirostris are treated as species, although the case for their separation, mainly based on different habitats and a small area of 'overlap' in W Uganda, seems debatable. Their vocalisations are identical and the different forms are so similar in appearance, with colour and size variations within subspecies, that the authors admit that they probably interbreed in Nigeria (and elsewhere?) and that ssp. ussheri, included in I. conirostris, may actually be a race of I. minor. No wonder many field workers are highly sceptical of this split and prefer to consider the forms as belonging to a single species, as they have been in the past, by White and Mackworth-Praed & Grant and, more recently, by Dowsett & Dowsett-Lemaire and Chappuis.

The species accounts are packed with information that updates BoA and with, thankfully, better referenced data. The authors state that the vocal repertoire of few barbet species has been studied thoroughly and that much remains to be learned. This comes as a surprise, as their far-carrying, repetitive songs uttered all-day long must rank among the most typical sounds of African forests and woodlands. It is fascinating to read how the habit of eating wax or cerophagy has led the honeyguides to a number of adaptations including of digestion, morphology and co-evolution with bees and man. Interestingly, the limited availability of wax also often results in concentrations of these normally solitary, aggressive birds at a food source, where there appears to be an inter- and intraspecific dominance hierarchy with, remarkably, immatures dominant over adults, and females over males. Immature Greater Honeyguides Indicator indicator are dominant over all others. The 'guiding' that gave honeyguides their name likely arose comparatively recently, and whereas in BoA the authors state that two species lead humans and other mammals to bees' nests, subsequent field work has led them to believe that only the Greater Honeyguide actually 'guides', and apparently only humans. Rather disappointingly, they now also consider unlikely tales of Ratels Mellivora capensis being guided. A minor point of criticism is that the authors appear to have reversed their, in my view laudable, decision, in BoA, to call the three distinctive, fine-billed Prodotiscus species honeybirds. These names are now being widely used and changing them back to 'honeyguide' does not contribute to the acceptance of standardised vernacular names.

Producing accurate distribution maps is an almost impossible task, in which the authors nevertheless appear to have largely succeeded. Only one map puzzled me: that for the little-known, central African Sladen's Barbet which, curiously, has a '?' in southern Mali and a x in Somalia or Ethiopia. No explanation is given for these highly improbable, not to say impossible, records. Unfortunately, the maps do not indicate country borders, which makes them rather difficult to interpret. That they could be improved upon is shown by Kemp's Hornbills monograph, the first volume of the series, in which the maps are larger and do indicate country borders.

The plates, of which only eight depict Afrotropical species, are generally accurate and artistically pleasing, although in a few of the Asian and American species leaves and branches are slightly too prominent for my taste. They are particularly useful as they illustrate many subspecies: 107 birds (of 56 species) have been depicted, against 88 in BoA. It is, however, a pity that the birds of the first honeyguide plate are not all depicted to the same scale; although this is indicated on the facing page, it remains confusing, especially as this is a difficult group.

Editorial errors, apparently inevitable, are few, the most conspicuous being that the space for the distribution map of Chaplin's Barbet (p. 198), is taken by a duplicate map of Yellow-billed Barbet, which, according to the caption, should have been a figure of a Chaplin's Barbet clinging to its nest entrance.

Considering the rather high price of the book and the fact that the acclaimed Handbook of the Birds of the World (HBW) has since published the chapters on these families, by the same authors, one may wonder whether it is worth the investment. Let there be no misunderstanding: HBW is a, admittedly splendid, summary. This work, the result of some 25 years of research by both authors, is the real thing. It is therefore essential to anyone, scientist or amateur, seriously interested in these attractive and intriguing families. Authors and publisher are to be congratulated for this authoritative monograph.

Ron Demey
References: 
Chappuis, C. 2000. African Bird Sounds: Birds of North, West and Central Africa and Neighbouring Atlantic Islands. 15 CDs. Paris: Societe d'Etudes Ornithologiques de France & London, UK: British Library.
Dowsett, R.J. and Dowsett-Lemaire, F. 1993. A Contribution to the Distribution and Taxonomy of Afrotropical and Malagasy Birds. Tauraco Research Report No. 5. Liege: Tauraco Press.
Fry, C.H., Keith, S. and Urban, E.K. (eds) 1988. The Birds of Africa. Vol 3. London, UK: Academic Press.
del Hoyo, J., Elliot, A. and Sargatal, J. (eds) 2002. Handbook of the Birds of the World. Vol 7. Barcelona: Lynx Edicions.
Mackworth-Praed, C.W. & Grant, C.H.B. 1970-1973. Birds of West Central and Western Africa. London, UK: Longman.
Sibley, C.G. and Monroe, B.L. 1990. Distribution and Taxonomy of Birds of the World. New Haven & London, UK: Yale University Press.
White, C.M.N. 1965. A Revised Check List of African Non-passerine Birds. Lusaka: Government Printer.

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