. Bonner zoologische Beiträge : Herausgeber : Zoologisches Forschungsinstitut und Museum Alexander Koenig, Bonn. Biologie ; Zoologie. Forêt de montagne afrotropicale disjonctions 197 oiseaux Les oiseaux forestiers sont donc une conséquence de la fragmentation d'une plage continue exi- sting lors glacials. Hall (1963) dans son examen de Francolinus acceptée du point de vue Moreau et considérées comme les populations isolées associées aux forêts de haute altitude comme des reliques d'un temps froid et humide, quand la forêt de montagne et le groupe dans son ensemble avait une distribution plus ou moins continue entre l'extrême p

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. Bonner zoologische Beiträge : Herausgeber: Zoologisches Forschungsinstitut und Museum Alexander Koenig, Bonn. Biology; Zoology. Afrotropical montane forest bird disjunctions 197 forest birds are thus a consequence of the fragmentation of a continuous range exi- sting during glacials. Hall (1963) in her review of Francolinus accepted Moreau's point of view and con- sidered the isolated populations associated with high altitude evergreen forest as relicts from a cold and wet epoch, when the montane forest and the group as a whole had a more or less continuous distribution between the extreme points where they are now found. Hall (loc. cit.) published a map of the assumed distribution of montane forest and the connections between the various mountain blocks, in a cold and wet area, and another map showing the immense area covered by forest in a warm and wet area. Livingstone (1975) noted that many montane species are highly temperature sensi- tive and that some populations of the species are widely disjunct from their nearest relatives. He suggested moreover that montane forest species were able to extend their range into lowland forest, when the climate was wet between 10, 000 and 7, 000 B. P. Although the distance is much shorter between East Africa and the Ethiopian high- land than between central Africa and Cameroon, only few birds were able to achieve the south-north passage across very dry country, while many montane forest birds took the more humid east-west route. Paleoclimatologists (see Livingstone 1975, for earlier references) have added new facts to our knowledge about the vegetational cover of the Afrotropical Region, during glacials and interglacials: the glacials correspond to very arid periods and even if the temperatures were low enough to move the montane forest boundaries to lower alti- tudes, the aridity was too high to support forest. These climatic conditions during glacials have been accepted by all biologists, espe- cially ornithologists dealin

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