Partridges, Quails, Francolins, Snowcocks, Guineafowl, and Turkeys

eductions in numbers or even extirpation of the gorgeted
wood-quail in Cundinamarca Department, Colombia
(Wege and Long 1995). The species is now restricted to a
small area of remaining forest in Santander and is in
critical danger of extinction (del Hoyo et al. 1994).
The clearance of habitat to make way for agriculture is
another common reason for habitat destruction. Forests
may be cleared for agricultural uses, such as plantations of
coffee, rubber, and tobacco, or for the grazing of livestock.
This is a particular problem where intensive farming
methods are used subsequent to habitat clearance, as vast
continuous tracts of land may become inhospitable. In
India, reclamation and conversion of large tracts of the
tall wet grassland in the Gangetic Plain has reduced the
availability of such habitat and is a major concern for the
conservation of the swamp francolin (Javed et al. 1999).
The Tacarcuna wood-quail is a Vulnerable and littleknown
species inhabiting humid forest within its tiny
range in Panama and Colombia. Clearance of its habitat
to make way for coca Erythroxylon coca plantations is a
major threat at present, as is habitat degradation through
mining activities and hunting for food (Alvarez-Cordero
et al. 1994). Increasingly, habitats are cleared for urban
settlement, road building, or reservoir construction. The
Sichuan hill-partridge is an Endangered species, and recent
survey work by Dai Bo et al. (1998) revealed that road
construction within the tiny range of this species is making
its forest habitat more accessible to logging operations
and to hunters. Although road construction itself may not
be severely detrimental to habitats, the opening up of
previously inaccessible areas means that habitat loss and
degradation may be accelerated. In Panama, completion
of the Pan-American Highway link through Darién could
lead to severe, long-term damage to the forest of the
Tacarcuna Ridge, thereby destroying habitat of the already
Vulnerable Tacarcuna wood-quail (Alvarez-Cordero et
al. 1994, Wege 1996).
Whatever the reason for habitat destruction, the
inevitable result of the process is increased fragmentation
in the distribution of a species. Habitat loss frequently
leads to the disruption of all but small blocks of suitable
habitat, which become separated from each other by large
expanses of uninhabitable ground. These habitat “islands”
contain populations that are often both small and isolated,
making them particularly at risk of extinction through
effects such as genetic drift, inbreeding depression, and
local catastrophe (Primack 1998). For example, local
populations normally able to recover from natural
disasters, such as floods, may be rendered too small and
isolated to withstand such devastating natural events.
Several extinctions of isolated local populations through
such episodes may rapidly add up to large-scale
disappearances of a species.
The swamp francolin, found in northeast India,
Bangladesh, and Nepal, has become localised in its
distribution through fragmentation of its wet grassland
habitat. This fragmentation may have increased the
vulnerability of this species to local extinction through
random natural events (Javed and Rahmani 1998, Javed et
al. 1999).
Habitat degradation is a reduction in the quality of a
habitat without the loss of all original vegetation. It can
result from activities such as selective removal of forest
products and grazing by domestic or feral animals. One
example is selective logging, where only a proportion of
trees (usually valuable species) is removed from the forest
in an area. This can vary in impact from the removal of a
small proportion of the standing trees, to the loss of all but
a few trunks. The associated problems, such as damage to
residual trunks and soil compaction, are discussed by
Whitmore (1984), while Marshall and Swaine (1992) more
fully discuss the effects of selective logging on tropical
forest. The term ‘selective logging’ is often taken to imply
that trees are harvested according to sustainable principles
and that alterations to forest structure are as limited as
possible. At its most extreme, however, the resulting forest
is severely degraded, with few trees left undamaged, and
with an unnaturally patchy and irregular canopy.
The Nahan’s francolin, until recently a very littleknown
species, is found in a few localities in the Democratic
Republic of Congo and Uganda. It is a strict tropical
rainforest specialist, and degradation of its habitat in the
Mabira Forest in eastern Uganda through intensive
agricultural encroachment appears to have led to a dramatic
reduction in bird densities in the area (Dranzoa 1998).
However, nearly half of the Mabira Forest has now been
given protection as a nature reserve and buffer zone. Work
is in progress to understand why this species was unrecorded
during a recent survey in Kibale Forest in southwestern
Uganda. Grazing within non-protected forests on Hainan
Island, China is considered to be one of the reasons for
reductions in the populations of the Hainan hill-partridge
(Gao Yu-ren in litt.).
Agricultural encroachment and habitat degradation are affecting
populations of Nahan’s francolin in Uganda.
© Lynx Edicions
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