The zoogeography of the montane forest avifauna of eastern Tanzania - Biogeography and Ecology of the Rain Forests of Eastern Africa - page 203

10 The zoogeography of the
montane forest avifauna of easten
Tanzania

S. N. STUART, F. P. JENSEN, S. BR0GGER-JENSEN AND R. I. MILLER

areas within a few kilomeres of forest (Stuart,
1983). This 'overspill' efect is sill vey poorly
understood from an ecological perspecive.
Seasonal alitudinal movements can make it dii-
cult to decide whether or not a species is 'mon-
tane'. Certain species are montane only through
part of their ranges. Examples include the Barred
Long-tailed Cuckoo Cercococyx montanus, Olive
Woodpecker Mesopicos griseocphalus, Grey
Cuckoo-shrike Coracina caesia, Pink-footed Puff-
back Dyoscopus angolensis, Lagden's Bush-shrike
Malaconotus lagdeni, Olive Thrush Tu rdus oliva-
ceus, Rufous-cheeked Ground-robin Shppardia
bocagei, Black-throated Apalis Apa/is jacksoni,
White-winged Apalis A. chariessa, Brown-headed
Apalis A. alticola and Dusky Flycatcher Musdcapa
dusta. In these cases we have included the mon-
tane populaions in the analysis and discussions in
this chapter. Other species can be considered
basically lowland but have isolated montane
subspecies which are included in this chapter,
these being Green Barbet Stactolaema olivacea
(subsp. bechei included), Elliot's Woodpecker
Mesopicos elliotti (subspp. johnstoni and kupeensis
included), Tiny Greenbul Phyllastrephus debilis
(subsp. albigula included), Liihder's Bush-shrike
Laniarius luehi (subspp. brauni and amboimensis
included), Many-coloured Bush-shrike Mala-
conotus multicolor (subspp. nigifrons and raueri
included), Masked Apalis Apa/is binotata (subsp.
pesonata included) and Margaret's Bais Batis
marga ritae (nominate subsp. included).
On the basis of the distribuion of montane

Inroducion
The evoluion and zoogeography of the montane
forest avifaunas of Africa have long been a source
of fascinaion to oithologists (e.g. Chapin, 1923,
1932; Moreau, 1933, 1952, 1954, 1963, 1966;
Dowsett, 1971, 1980a,b; Hamilton, 1976;
Diamond & Hamilton, 1980; Stuart, 1981a,
1983, 1986; Jensen & Stuart, 1985). The mon-
tane forests are characterised by many
alitudinally restricted species which usually have
disjunct distribuions reflecing the patchiness of
the available habitat. Many lowland species occur
in Africa's montane forests, but do not necessarily
do so as isolated populaions; these species are
not considered here. For the purposes of this
chapter we have defined montane forest species as
those which do not normally occur below a certain
alitude (in easten Tanzania, few such species
occur below 700-900 m a.s.l. during the breeding
season), and which seem to be dependent upon
forest or their survival (usually for nesing sites
and food). Thus species restricted to forest at
intermediate elevaions (usually between 700 and
1500 m), such as the Banded Green Sunbird
Anthrptes ubitorques, are considered here to be
montane.
It is not always easy to decide what is a forest
species and what is a montane species, since the
disinctions are not necessarily hard and fast ones
(see Stuart, 1983 for a fuller discussion of this
problem). One complicaion is that many forest-
dependent species are able to survive in cleared

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