Working for birds in Africa

The Birds of Africa. Volume 5: thrushes to puffback flycatchers

Fri, 12/28/2012 - 14:47 -- abc_admin
E. K. Urban, C. H. Fry and S. Keith (eds). 1997. Academic Press, London. 660 pp, 32 colour plates, 347 distribution maps.
pages 60 - 64

At last; this volume has appeared five years after the publication of the last one, but it has been worth the wait. It treats thrushes not dealt with in Volume 4, the Old World warblers and flycatchers. The series has improved with time and a number of innovations in this volume add to the accuracy and value of the book. A few (including the gazetteer and red shading on the maps which indicate breeding areas), are major steps forward and enhance the value of the series as a whole. A positive advance, from a fieldworker's viewpoint, would have been reference to a standard colour key when describing egg colours and other features (plumages are largely catered for by the colour plates); perhaps this innovation can be added to forthcoming volumes, assuming that source material is available. As before, a number of experts have written the texts ensuring that the accounts are as accurate as possible. Individual authors, in consultation with the editors, were given carte blanche to make their own taxonomic interpretations resulting in some rather different opinions than we in Africa are used to. The acoustic references are comprehensive and make the location of a particular song-type even easier than before. The illustrations are all excellently done - although somewhat duller than the printers proofs, which I saw at the 1997 Rutland Water Bird Fair - and Martin Woodcock is to be congratulated. However, a number of inconsistencies in the artwork left me wondering whether taxonomic decisions were made independently of the artist. I am unsurprised at the lack of natural history data for many species covered here. Compare, for example, the information on European Reed Warbler Acrocephalus scirpaceus, with African Reed Warbler A. baeticatus. There is much scope for good natural history data on these and other species (witness the number of accounts where nests, incubation and fledgling periods are unknown). The dearth of indigenous African ornithologists, north of the Limpopo River, contributes to this and until the malaise in the affairs of the continent is turned around, this lack of data will continue. Also, the current trend in world ornithological journals to publish cutting-edge science at the expense of solid natural history studies is worrying in an African context, particularly when so many birds are under threat. There are few international journals which will publish general biology papers, and those African journals which accept such work have a limited circulation or are beset with financial worries due to collapsing currencies. It is worth remembering that we cannot adequately protect species of which we know little, but data presented on many species in this volume goes some way to highlighting the need for natural history data, some of it urgently. Surprisingly, a number of names are re-introduced in this volume and in some cases the authors have adopted common (and sometimes scientific) names unused in Africa for many years. The authors should have attempted to retain names in current use eg in southern and East African field guides. Some of the more obvious changes include Moustached Grass Warbler Melocichla mentalis (in East Africa this is the African Moustached Warbler, in southern and central Africa the Moustached Warbler); Cape Grass Warbler Sphenoeacus afer for Grassbird; Miombo Wren-Warbler Camaroptera undosa for Miombo Barred Warbler in East Africa and Stierling's Barred Warbler in southern Africa. In East Africa, common name changes include Moreau's Tailorbird Apalis moreaui for Long-billed Apalis and African Tailorbird Orthotomus metopias for Red-capped Forest Warbler, to name a few. There is inconsistent use of common names within Phylloscopus. Some are called Willow Warbler and others, within the genus, have woodland added to their names eg Yellow-throated Woodland-Warbler P. ruficapilla, following the names used in East Africa. As they all occur in woodland of some description, I think this could have been omitted. Some prinias are placed in the genus Schistolais; if ever there was cause for inventing a new common name, perhaps it is here? Common names for Parisoma are a nightmare of confusion. Layard's Warbler/Tit-babbler Sylvia layardi, Chestnut-vented Warbler or Tit-babbler S. subcaerulea and Brown S. lugens and Banded Parisoma S. boehmi are names used for members of this genus; it might have been more sensible to apply one common name (tit-babbler, warbler or parisoma), as, with time, such uniformity might gain acceptance. Mariqua Flycatcher Bradornis mariquensis has not been used in southern Africa for a number of years and Marico is now in common use. As this bird occurs almost exclusively within the confines of southern Africa, I cannot understand why an outdated name has been used in preference to that in common use. The taxonomy in this volume is inconsistent although, to be fair, some species under consideration are little known. The taxonomic approach is varied and in some cases voice is given more emphasis than equally important factors, such as DNA. As so little is known about some species, I would have presumed that the molecular evidence of relationships would have been given precedence, but this does not appear to be the case. Some decisions are well-defended but others - particularly where forms have been treated as subspecies and molecular evidence suggests otherwise - not so well. The rules are inconsistently applied, being used in some instances and ignored elsewhere, particularly in examples where change appears justifiable. In respect of subspecies, opinions will always vary, as noted by Irwin (review of The Birds of Africa Vol 4, Honeyguide 39:39-42) and many forms are liable to recognition when only the specimens in European and North American museums are examined; an occasionally uneven treatment of subspecific and specific taxa reflects this. This volume is beset by this particular problem because it deals with the warblers and flycatchers, of which many are little-known in the field and appear very similar in plumage when skins are examined by authors not resident on the continent. Those living in Africa often possess in-the-field experience but may lack the perspective gained from looking at specimens from across the continental range of a species, because of a lack of access to the museums concerned. At times, this makes species limits decisions for familiar birds very difficult to swallow. In the present day, I wonder just how useful the superspecies concept is. It appears to stifle new approaches to inter-species relationships and tends to assemble taxa into larger groups on the basis of appearance, which may make little sense in molecular terms. I believe that adherence to this concept has resulted in much of the taxonomic confusion that exists today and that we should be more open-minded to those molecular studies which produce unexpected results. For example, on DNA evidence there are three families in Sylviidae with some non-conventional inserts (eg bulbuls), but some African workers do not recognise this. The editors of The Birds of Africa have adopted a policy of following convention for Palearctic genera (reflecting their Holarctic roots) but Afrotropical genera are sorted in an order of their own making, adding to existing confusion. Some genera are transferred to flycatchers and babblers, although 44 African genera are in fact too little known to produce an evolutionary tree. This is important when discussing avian diversity in the Afrotropics, as taxonomic decisions ultimately determine the number of species in a given area. To be more specific, the placement of Groundscraper Thrush Psophocichla litsipsirupa into the monotypic genus Psophocichla appears reasoned and logical. I wonder if the Orange Ground Thrush Zoothera gurneyi population in Angola still exists and if it is really the same subspecies that occurs in Tanzania, Malawi and Zambia?. Sixteen subspecies of the Olive Thrush Turdus olivaceus are mentioned and the taxonomic note notes the persistant confusion but does not mention that some are essentially savannah forms (eg T. libonyana south of the Zambezi) while others are mainly restricted to forest. Other differences exist between the savannah and forest forms (eg significantly different egg colours - pale green and blotched in the savannah forms; light blue and relatively unmarked in the forest forms - and their DNA). There is much scope for future work on the basis of behaviour, vocal and molecular studies and I would not be surprised if there were some cryptic species in this conglomeration. Among warblers 45 genera and c210 species are currently recognised in Africa, and thus there is bound to be some disagreement and differences in interpretation of taxonomic relationships. In the text for Bradypterus baboecala it states that B. b. tongensis occurs in east and south Zambia and extreme east Zimbabwe in the Zambezi Valley from Tete to the Chobe River. Previously, it was stated to be largely absent from the Zambezi Valley which is confirmed by the distribution map. Another race merges with tongensis on the Chobe River but there is essentially no suitable habitat for this species below Victoria Falls and there is also no illustration of the well-studied southern form, which is much darker above and below than that which is illustrated. River Warbler Locustella fluviatilis is stated to be widespread in Zimbabwe during the austral summer but this is not supported by observations: it is very rare with perhaps two sightings a year. The large concentration reported in north-east Botswana in the austral summer was perhaps a one-off. The problem is that the land where the birds were wintering is inaccessible without a permit, which can only be obtained, after an exhaustive bureaucratic process, through the local wildlife agencies. The editors have dispensed with African Marsh Warbler in preference to African Reed Warbler, which they have retained as baeticatus despite suggestions that it is conspecific with European Reed Warbler. I agree with this decision, as it reflects its close taxonomic affinities with European Reed Warbler. However, the distribution map is surely a gross overstatement of its breeding range, particularly in southern Africa, reflecting observer confusion with similar warblers. The distribution map of Greater Swamp Warbler Acrocephalus rufescens on the Upper Zambezi is very disjointed: is this real or a function of the data available? In this area, it occurs in small patches of papyrus and, if papyrus occurs most of the way upstream from Victoria Falls, then the species will probably occur throughout. The two subspecies apparently occupy different habitats in West and East Africa, leading one to speculate that the two taxa might be specific - they appear quite dissimiliar. Certainly, the nest situation of a West African form was different to nests on the upper Zambezi. The taxonomic notes, which complete each cisticola species account, suggest that there is much taxonomic work to be done on this group. Sibley & Monroe suggested that the cisticolas are a distinct group within the Sylviidae, which should give some inkling of the possibility of a number of undescribed species. All such work has taken the form of molecular studies, but the authors ignore molecular differences in some cases (Cisticola chubbi and C. discolor) and opt for more traditional viewpoints. I understand that there are a number of undescribed cisticolas in Tanzania, highlighting the urgent need for taxonomic work on this group. Several taxa, presently considered species, were originally described as subspecies (eg C. bodessa (C. subruficapilla bodessa), C. njombe (C. aberrans njombe ), C. aberdare (C. robusta aberdare)) and it is possible that other subspecies in the C. laiso, C. galactotes and C. aberrans complexes are also meritorious of full species status, but data are currently lacking. Red-faced Cisticola Cisticola erythrops song is as a duet but this is not easily detected in the field despite specifically listening for it. Is C. e. nyasa, including arcana and elusa, the same as more northerly forms? C. lepe is treated as a subspecies of C. erythrops contra to some previous work, which accorded it full species status. I am unconvinced that C. discolor is conspecific with C. chubbi: genetic evidence suggests they are different and song playback results are equivocal. In my view, the authors should have stated that song similarities may exist but, until these are better studied, they followed genetic evidence in treating these forms as different species. The emini subspecies of Rock-loving Cisticola C. aberrans has different DNA but similar morphology and song to other forms and is therefore lumped with them. No mention is made of the significantly different song of C.a.nyika, which does not respond to playback of South African birds. It occupies a different habitat to these and is perhaps specifically distinct. In view of this, I wonder just how similar the calls of C.a. emini are to those of other forms and if it is best treated as a subspecies. Wailing Cisticola C. lais includes a variety of potentially new forms, eg Lynes's Cisticola C. distinctus, which is accorded specific recognition by Zimmerman et at but not by Dowsett & Forbes-Watson. Also included in this complex are C. l. mashona and C. l. oreobates from Zimbabwe and Mozambique, one of which has a very distinct breeding plumage not shared by the other, although this is not mentioned in the text. Indeed, oreobates may warrant specific recognition. It is extremely difficult to discover what the breeding plumage of any of the forms of Winding Cisticola C. galactotes looks like, as each section, almost without exception, refers the reader to a previously mentioned subspecies. From the same text, it is obvious that these subspecies' songs and, to some extent, habitats are different, but no mention is made of the possibility that more than one species may be involved. From a Zimbabwean perspective, isodactylus (the form occurring in the south-east of the country) is treated within suahelicus, but subsequently it is stated that galactotes is the form occurring in the south-east. This viewpoint rests on Lynes' (1930s) opinion and ignores a more recent (1960s) analysis which lumps the south-east Zimbabwean lowveld forms with those from Mozambique, which is far more likely. The authors appear not to have examined specimens from this area. If they had, they would surely have commented on the obviously grey head, grading into the grey back in non-breeding plumage of isodactylus. These birds are very obviously not suahelicus or galactotes on this basis, although they respond well to the call of galactotes from Kwazulu-Natal in South Africa. In breeding plumage, the head assumes a grey-brown colour - quite unlike the form occurring in north-west Zimbabwe. The distribution of the luapula subspecies is more widespread than given and it is likely that it, schoutedeni and stagnans are all conspecific - previously suggested by a number of authors but ignored here. These birds do not respond to the calls of galactotes from Kwazulu-Natal or East Africa, but with some vigour to calls from within their restricted-range (most of Zambia, north-east Namibia, north-east Botswana and north-west Zimbabwe). The described habitat occupied by a number of forms across its vast continental range varies from all types of marsh vegetation, except dense papyrus (although it is occasionally found there in north-west Zimbabwe), especially at the edge of open water etc, highland streams and marshes, highland grassland, broadleafed tall grass savannah and Acacia short grass savannah in Ethiopia, and bush, cultivation and dunes in East Africa. It is worth questioning whether these constitute the same species, as they occupy such a wide variety of habitats over a range of altitudes and localities, and possess a number of distinctly different songs and plumage types. In my opinion, there are potentially a number of full species within this complex. The Pectoral-patch C. brunnescens and Pale-crowned Cisticolas C. cinnamomeus are treated as full species (previously the form occurring in Zimbabwe was considered to be C. brunnescens cinnamomea) although the rationale for this is not well-explained (it appears to be on the basis of some instances of sympatry between the two and Wing-snapping Cisticola C. ayresii in Gabon). The description of breeding plumage Pale-crowned Cisticola is unconvincing; the form in Zimbabwe is more like the description of Pectoral-patch Cisticola and is similar to that illustrated in Zimmerman et al, which on this treatment is not cinnamomeus but brunnescens. The decision to split the two also caught the artist off-guard and Pale-crowned Cisticola is 'stuck' between a number of races of brunnescens. As a result, variations in cinnamomeus are not illustrated, including the obvious breeding plumage. A detailed taxonomic note is warranted under brunnescens and not under ayresii, which is a very different bird altogether. Additionally, I found the explanation under ayresii to be unconvincing as there is no literature citation but many pers. comms. without obvious supporting data (eg tape recordings or specimens) of the birds in question. The variation in the plumage types of Bar-throated Apalis Apalis thoracica is almost unbelievable and a detailed appraisal of the DNA of these forms might reveal some surprises in terms of their relationships. The occurrence of different songs among these forms (fuscigularis) is mentioned, and the comment that some incipient speciation may be occurring in this group appears an understatement. This group deserves intensive work, a comment equally applicable to most members of the genus. Rwenzori Apalis A. ruwenzorii was initially considered a form of A. pulchra, on the basis of vocal similarity, but is now recognised as a species on the basis of distribution, plumage characters and its differing number of tail feathers. Likewise, Yellow-breasted Apalis A. flavida occurs in a number of locally sympatric and vocally distinct forms, suggesting that a number of unrecognised species are currently retained in this grouping. My experience of Black-headed Apalis A. melanocephala in the lowland forest of Zimbabwe indicates that it has red-brown eyes (confirmed from specimen-labels at Bulawayo Museum), but most illustrations depict the species as having pale irides. Is this significant in a breeding context, as the birds we saw were in the non-breeding season? Chapin's Apalis A. chapini is specifically distinct from A.porphyrolaema due to its different head and breast pattern, and voice, as is Brown-headed Apalis A. alticola which was recently discovered to be sympatric with the Grey Apalis A. cinerea in parts of its range, supporting the contention of some authors (eg Sibley & Monroe) that it is a species. Five apalis species have grey backs and rufous throats / upper breasts, making sight records very difficult to verify, and I wonder what the impact of sight records has been on the distribution maps presented here. Also, given different skin preparation techniques and possibly undescribed plumage variation, how accurate has the identification of these forms in the museum been? The placement of Apalis moreau and Orthotomas metopias in the genus Artisornis coupled with a change in their common names could have been better defended and explained. Bleating Warbler Camaroptera brachyura is a contentious species whose exact limits and races have been the subject of much debate and taxonomic revision over a long period. Here, it is retained in the lumped form (with some misgivings) and despite strong evidence (molecular and otherwise eg song and preferred habitat) that brachyura and brevicaudata are perhaps distinct enough to warrant separate species status. Hybridisation has been reported in zones of contact but some supposed hybrid specimens in Bulawayo Museum can be allocated to one taxa or the other with some confidence. My belief is that two species are involved. I concur with the placement of the small grey warblers, some of which are barred below, which occur in the woodlands of central Africa in Calamonastes but disagree with the comment that 'all forms might be considered well-marked races of a single species', which made me wonder how well the authors know these warblers in the field, if at all? The taxonomy is no better for the treatment given this group and if anything has taken a retrogressive step, as in the field these birds are quite different. Detailed analysis of these forms' songs is presented in the voice section of C. undosus and the differences between simplex / undosus and stierlingi highlighted. As the use of song / voice differences has been used in this volume as a justification for some taxonomic decisions, I was very surprised to note that obvious differences in the song of these birds has been ignored in this respect. The calls of C. stierlingi and simplex from Zambia are very different as is the habitat occupied with simplex occurring in richer (=moister) Miombo woodland than stierlingi. Benson et al mention a hybrid zone but some such specimens held in Bulawayo could quite easily be separated into stierlingi or simplex, although Stjernstedt has a taperecording of an apparent hybrid from the area of overlap. It seems that they have been unnecessarily lumped on the basis of their plumage alone (which in my opinion is unconvincing) and without taking into account the song and habitat differences between the two. A more logical arrangement would be: C. simplex in the north, C. undosus entices in Rwanda, Tanzania, Angola, Congo and north Zambia, C. stierlingi in the rest of Zambia, Zimbabwe, east Botswana, south-west Angola, Caprivi (Namibia), Mozambique and South Africa and C. fasciolatus in Namibia, south-west Angola, Botswana and the Transvaal (South Africa). A taxonomic note suggests that a number of species (two or more?) may be involved in the Pale=Pallid Flycatcher Bradornis pallidus complex and stresses the need for field studies of the various forms. This applies to all species for which there is dispute over the number of races and their status. Certainly the distribution map of this species suggests that a number of species may be involved - fieldwork will prove or refute this. Whilst Zimmermann et al use Lead-coloured Flycatcher, The Birds of Africa coin the new (?) name Grey Tit-Flycatcher for Myioparus plumbeus. To my mind, Fan-tailed Flycatcher is probably the best name as it well-describes the bird and its actions. The other member of the genus, M. griseigularis, could be called Grey-throated Fan-tailed Flycatcher - no less of a mouthful than Grey-throated Tit-Flycatcher and probably describes the bird much better. These taxa were originally considered to be warblers and, given the behavioural similarities between Fan-tailed Flycatcher and Fairy Flycatcher, there may be some justification for treating them within the same genus. The monotypic endemic Fairy Flycatcher Stinostira scita has been through the taxonomic mill, having been variously treated as a muscicapid flycatcher, monarchid flycatcher and a sylviid warbler by different authors. The authors make a novel suggestion that Myioparus plumbeus is close enough to (presumably based on behaviour) Stinostira and that they should both probably be placed in that genus (which pre-dates Myioparus). Molecular data suggest it is a warbler and fieldwork should help assess its evolutionary placement and relationship to Fan-tailed Flycatcher. Genuine plumage variability is recorded in Paradise Flycatcher Terpsiphone viridis but it is not stated how this affects the subspecies which are subsequently described and some confusion in taxonomy results: male T. v. viridis is described as having deep rufous upperparts, white wing edgings, glossy blue-black throat extending onto breast, and rufous tail and undertail coverts. This race is illustrated as having the back, all upperwing-coverts, tail, undertail-coverts and lower breast white; the flight feathers, mid- and upper breast, head, nape and crest are blue-black. Reports of hybrids between T. viridis, T. rufiventer, T. bedfordi and T. batesi, based solely on the study of museum skins should, I believe, be reported with caution, due to the large amount of individual variation in subpopulations of these species. I concur that field studies in areas from where 'hybrids' have been reported would be most instructive. Flycatchers, wattle-eyes and batis are other groups which have been through the taxonomic treadmill, having been variously treated as flycatchers, shrikes, warblers and thrushes. Molecular studies have demonstrated that some are closest to crows, bush-shrikes and helmet-shrikes. A complete study of the calls, behaviour, nesting and DNA of each species might heighten our understanding of their taxonomic affinities. The forms of Red-cheeked Wattle-eye, Dyaphorophyia blissetti blissetti and D. b. chalybea, are considered the same species by some, as they occur in the same location at different altitudes, but as allospecies by other authorities. They appear different on the basis of this book's illustrations and, despite the authors decision to treat them as conspecific until more data are available, they seem safely separable to me. Likewise, the three subspecies of Yellow-bellied Wattle-eye D. concreta look different, do not overlap in distribution and habitat, and sing differently; characteristics which have previously been used to justify specific separation. Opinions concerning the species limits and superspecies affiliations of batis have varied greatly over the years and the final say will presumably be had by students of vocal and other social communication characteristics. A number of species are almost identical, creating major problems in the field for the uninitiated and past mistakes with identifications, even in the museum, will be very difficult to rectify. For example, plumage differences between Senegal Batis Batis senegalensis and Angola Batis B. minulla are not as great as those between B. poensis poensis and B.p. occulta, which are probably separate species (as suggested by Lawson). Additionally, the accompanying taxonomic note does not detail the distribution of B. p. occulta at all. If their ranges overlap, then there are certainly two species involved, but this decision cannot be made according to the information presented here. The songs of Cape Batis Batis capensis kennedyi (the isolated Zimbabwean population) are different from those in the Cape. Although these two populations are morphologically similar, the territorial calls are different (although both respond to and make the same mobbing call). It is also difficult to determine the exact ranges of B. c. hollidayi and B. c. capensis, as details of their distribution suggest that the two forms overlap in the Kwazulu-Natal region of South Africa, making me speculate on the subspecific validity of hollidayi. This illustrates just how difficult it is to make an informed decision using a single feature (eg plumage, distribution or voice) and that the multi-taxonomic viewpoint is probably the most informed option to take. From a southern African perspective, some distribution maps had errors. Records of Red-winged Warbler Heliolais erythroptera in Kruger National Park, South Africa are erroneous. The map for Burnt-necked Eremomela Eremomela usticollis incorrectly shows a gap in Hwange National Park, Zimbabwe where it is regularly found. Likewise, the dashed line dividing the northern long-billed forms of Long-billed Crombec Sylvietta rufescens from southern short-billed forms does not equate with that described in the text. The 1994 record of Blackcap Sylvia atricapilla in eastern Zimbabwe has been overlooked, although this suggests that some birds may wander down the Rift Valley. The isolated population of Black Flycatcher Melaenornis pammelaina in the Kalahari desert of Botswana is erroneous and the occurrence of Yellow-bellied Hyliota Hyliota flavigaster in the Caprivi of Namibia is unproven. Records of Blue-mantled Crested Flycatcher Trochocercus cyanomelas at Victoria Falls are unacceptable and considered to be misidentifications (for a Puffback Shrike Dryoscopus cubla in one instance). No population is known from nearby so the supposed records cannot be of local birds and in the absence of a specimen are best ignored. There are remarkably few typographical errors: two I found were Chinanimani mountains = Chimanimani Mountains on p. 76 and Herremans, M. not H. (under River Warbler). I regularly use the already published volumes as a baseline from which to plan further work or to discover what is known of the birds in which I'm interested. Despite the comments above, this volume is the best yet and if all the remaining volumes are as good, then we really have something to look forward to. By highlighting the gaps in our knowledge, the authors are providing an important service whereby it can be pinpointed if new observations add to existing knowledge of little-known species, some of which have limited distributions and possibly small populations. Time is of the essence in this production though and I trust that the remaining volumes will be produced a little more quickly than this one. In addition, the Handbook of the Birds of the World is being published at such a rate, it could overtake The Birds of Africa as the first choice information source on African birds. It is up to the editorial team to see that this does not happen.

Dr Kit Hustler
References: 
Benson, C.W., Brooke, R.K., Dowsett, R.J. and Irwin, M.P.S. 1971. The Birds of Zambia. London, UK: Collins.
Dowsett, R.J. and Forbes-Watson, A.D. 1993. Checklist of birds of the Afrotropical and Malagasy Regions. Liege, Belgium: Tauraco Press.
Lawson, W.J. 1984. The west African mainland forest dwelling populations of Batis; a new species. Bull. Brit. Ornithol. Cl. 104:144-146.
Lawson, W.J. 1986. Speciation in the forest-dwelling populations of the avian genus Batis. Durban. Mus. Novit. 13: 285-304.
Sibley, C.G. and Monroe, B.L., Jnr. 1990. Distribution and Taxonomy of Birds of the World. New Haven & London, UK: Yale University Press.
Stjernstedt, R.J. 1993. Birdsong of Zambia. Privately published.
Zimmerman, D.A., Turner, D.A. and Pearson, D.J. 1996. Birds of Kenya and northern Tanzania. London, UK: A.& C. Black.

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