Jozani biodiversity inventory report 2002 - Coastal Forests of Kenya ...

threat to reptiles, amphibians and invertebrates. Serious fires damage habitats, so reducing
their quality. Fire may also cause changes in species composition of an area through
encouraging some species and supressing others.
7. Habitat loss and fragmentation
This arises mainly from converting natural vegetation into agricultural land or settlements. It
is a major threat to most fauna species from large mammals to invertebrates. The decline in
the Zanzibar red colobus numbers is mainly attributed to habitat loss and fragmentation. This
factor is also known to affect to some extent the duiker species in the area. There are
obviously many other species affected in this way. It has been observed in Usambara
Mountains that frugivore species declined with decreasing forest fragment size. Consequently,
the loss of these dispersal agents depressed tree recruitment in the course of forest
fragmentation (Cordeiro and Howe, 2001). The lepidopterans (Butterflies and Moths) are
completely dependent on specific plant species during their larval stage, which is the feeding
stage. Any activities that result in the loss of the natural vegetation would adversely affect this
group of insects. The larval stage of Dragonflies and Damselflies (Odonata nymphs) are
aquatic predators. They are completely dependent on availability of fresh-water habitats. Any
activity that results into modification or loss of fresh-water bodies would adversely affect the
Odonata. For marine environment harvesting methods such as dynamiting and use of beach
seines can cause serious habitat damage.
8. Hunting/over exploitation
This includes both illegal and uncontrolled legal hunting. Hunting is the main cause of the
decline in numbers of duikers and blue monkeys in the survey area. It is reported that there is
increased demand for wild meat and trophies by tourists coming to the south eastern Zanzibar
and this is a potential threat to some animals especially the antelopes. Fish, molluscs and
other marine resources are adversely affected by over exploitation.
9. Diseases
Transmission of diseases between people-wildlife-livestock has been reported to occur in
Tanzania (GL-CRSP, 2002). Primates are close relatives of humans and diseases like polio,
pneumonia, measles and flu and there are over 20 known, potentially lethal viruses that can be
transmitted between non human primates and humans including Ebola, Marbug, hepatitis A
and B, herpes B, SV40 and SIV (Fano et al, nd). The possibility of such an event is high
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