The zoogeography of the montane forest avifauna of eastern Tanzania - Biogeography and Ecology of the Rain Forests of Eastern Africa - page 224

Weaver Ploceus nicolli is most closely
related to the Olive-headed Golden
Weaver P. olivaceiceps (Franzmann, 1983).

together today did not evolve sympatrically and so
it is not surprising that the montane communiies
are now composed of species with diverse origins.
Table 10.3 presents data on the relaionships
between certain Montane Forest Groups. It can
be seen that 91 % of the South Malawi species
and 78% of the South of Zambezi species occur
in the East Coast Escarpment. These two
southen Montane Forest Groups are best con-
sidered to be composed of disincive species
assemblages, almost all of which are probably
derived from the easten Tanzanian forests. The
Cenral East African Montane Forest Group is
best considered a merging zone between the East
Coast Escarpment and the Alberine Rift, with
64% of its species occurring in the former and
78% in the latter. Species that originated in the
East Coast Escarpment seem to have spread both
to the north and to the south. It should also be
noted from Table 10.3 that nearly half (47%) of
the East Coast Escarpment species occur in the
Alberine Rift. It is therefore probable that the
orests of easten Tanzania have 'received' spe-
cies from this latter source (which is the major
centre of montane species diversity and endem-
ism in Africa) in addiion to 'contribuing' species
to other parts of the coninent.

The remaining 36 species, which are neither
endemic nor near-endemic, fall into two groups:

5. Six species are confined to montane forest
n the East Coast Escarpment but range
widely through lower alitude woodlands
and forests in some other parts of Africa.
These are the Barred Long-tailed
Cuckoo, Olive Woodpecker, Black-fronted
Bush-shrike, Olive Thrush, Brown-
headed Apalis and Dusky Flycatcher. The
origins of all these widespread and
adaptable species cannot be readily
determined.
6. The remaining 30 species are all
widespread (more or less) montane forest
species. Evidence from present-day
disribuion pattens suggests that at least
some of these probably speciated in the
East Coast Escarpment but have since
spread well beyond its limits. The likely
such species are the Moustached Green
Tinkerbird Pogoniulus leucomystax, Sripe-
cheeked Greenbul, Yellow-throated
Woodland Warbler Phylloscopus ruicap ila,
Bar-throated Apalis Apa/is thoracica,
Easten Double-collared Sunbird and
Kenrick's Starling. Many of the other
species probably originated elsewhere in
Africa, most likely in the species-rich
Alberine Rift forests, though possibly also
in Cameroun.

Conclusion
From the overview presented n this chapter, it is
clear that enough is now known of the zoogeogra-
phy of the easten Tanzanian montane forest avi-
auna to give a descripion of its relaionships to
aviaunas elsewhere in the coninent, and of its
diversiy, endemism, disribuion pattens,
subspeciaion and seasonal movements as well as
its likely origins. However, this overiew requires
one major qualiicaion. Many parts of the East
Coast Escarpment are yet to be eplored. For
instance, almost nothing is known of the northen
extension of the Nguru Mountains west of
Handeni, nor of the Rubeho Mountains, the
Uvidunda Mountains, most parts of the Uzung-
was (especially the northen extension at Image),
nor most parts of the Southen Highlands.
Mountains lying outside the main escarpment,
notably Malundwe, Mahenge, the Mbarika

The East Coast Escarpment Montane Forest
Group, therefore, has diverse origins. The mon-
tane species communiies occurring in Africa
today are clearly composed of species which have
evolved, dispersed and conracted in large part
independently of each other. Stuart (1983) car-
ried out several analyses of bird disribuion from
biogeographical, ecological and morphometric
angles. In each case the evidence or communiy-
wide interspeciic compeiion having a major
influence on bird distribuions was equivocal. It
seems likely that many species which occur