Working for birds in Africa

Forest Birds In Côte d'lvoire. A survey of Tai National Park and other forests and forestry plantations 1989-1991

Sat, 29/12/2012 - 14:02 -- abc_admin
Mary E. Gartshore, Phillip D, Taylor and Ian S. Francis, 1995. Study Report 58, BirdLife International, Cambridge. 81pp. Available from Natural History Book Service, 2-3 Wills Road, Totnes, Devon TQ9 5XN, UK. £5.50
pages 136 - 137

Tai National Park (330,000 ha) is by far the largest and best-preserved remnant of rainforest in West Africa and is as such of critical importance for the survival of many species. Despite its importance no detailed studies of its avifauna had been undertaken before the present study. The aims of the project were not only to collect information on the status and ecology of the birds occurring in Tai particularly the threatened and near-threatened species but also to investigate other forests and forest plantations in order to compare their species composition with that of Tai. Of the eight threatened and five near-threatened bird species found in Tai the study reports four threatened and all five near-threatened species from forest reserves in Côte d'lvoire. The most remarkable finding however is that two threatened and three near-threatened species also appear to frequent commercial forest plantations (Western Wattled Cuckoo Shrike, Nimba Flycatcher, Brown-cheeked Hornbill, Copper-tailed Glossy Starling and Rufous-winged Illadopsis). These findings together with other results suggest that for some bird species plantations begin to resemble natural forest after c20 years and therefore could play an important role in maintaining species diversity. I was particularly interested in the field methods employed during the study. Unfortunately the overall efficacy of bird-census techniques in a tropical forest environment remains limited. At best the results of all methods combined only seem to be able to point out the obvious, at worst they are difficult or impossible to interpret. Clearly, more research is needed to develop a more adequate methodology. In an attempt to find some order in the apparent chaos of field data the report frequently makes use of statistical methods and formulae, so that the text in places becomes unintelligible for someone unfamiliar with these. Although it may be perfectly sound to perform 'a PCA on the covariance matrix of the resulting data' or to compute 'the chi-square probability of Fisher's exact test for the two-way table', I cannot but note that these sorts of methods often just result in trivialities - for example the conclusion that some species are more often found in bird parties than others (or as the authors put it 'show a significant positive association' with bird parties). I was rather surprised to learn that canopy surveys from temporary platforms did not seem to be particularly productive; apparently they are not really worth the effort. The inclusion of maps of all forests and forest plantations studied, with an indication of the area visited, would have considerably enhanced the practical value of the study. It would have permitted, among other things, an understanding of why the data recorded in Yapo Forest are so divergent from those collected by others who know this forest well (cf Demey & Fishpool 1994, Malimbus 12:100-122). In view of the Yapo list of 225 species, the number of 82 species found during the present study seems particularly low, even if observations were limited to four or five field days (by how many observers?). The reason for this low species total remains unexplained. Truly remarkable is the composition of the species list. Species that are common to not uncommon there such as Ansorge's, Spotted, Red-tailed, Yellow-bearded and Golden Greenbuls were missed, while a rare species such as Green-tailed Bristlebill is claimed. Even more surprising is the absence of malimbes, while scarce species such as White-breasted Negrofinch figure on the list. There are other anomalies, eg the absence of Tit-hylia, Chestnut-capped Flycatcher, Black Bee-eater and White-crested Hombill but presence of the much more rarely recorded Blue-headed Crested Flycatcher, Blue-headed Bee-eater and Black-wattled Hombill and no owls, but Brown Nightjar! All this makes me very curious to know which part of the forest was visited. It also clearly demonstrates that a short visit can only produce rather biased data which may give an inaccurate picture of the site. As a consequence comparisons between the avifaunas of the sites covered by this report cannot be made with confidence and hence the checklist given in Appendix 1 is rather misleading. Details are presented on Red Data Book species, but it is a pity that more notes on other species of interest have not been included. The sightings of Pale-fronted Negrofinch constitute the first for Côte d'lvoire and should be properly documented, especially given the paucity of records from the Upper Guinea forest block. Details should also have been given on Brown Nightjar, the sightings of which constitute the first definite records for the country. In these times of nomenclatural and taxonomic uncertainty, I always find it particularly annoying not to know which authority has been followed. This should be mentioned, especially in a study on African birds. These criticisms should not detract from the fact that this attractively produced report, based upon extensive field work, contains a lot of interesting information and at the same time indicates how much remains to be discovered. It is therefore highly recommended to anyone seriously interested in the West African forest avifauna.

Ron Demey

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