Tana Delta Irrigation Project, Kenya: An Environmental Assessment

Table 19. Spatial distribution and temporal trend notes by forest.
Forest # Forest Name Comment
46 Sailoni West 1 The one troop of red colobus reported in 1994 has not been reported
since. A troop of mangabeys was observed that hadn’t been seen here
before and should be considered to be a genetically isolated group. The
only other mangabey troop in this area that could possibly be the troop
sighted, is the troop in forest patch #49, recorded in 2001. This is only
one of two small forest patches where mangabeys were found; the other
forest patch is #69.
47 Sailoni West 2
48a Kulesa East All species recorded have been recorded for forest #48a. #48b was not
located and no troop sightings were recorded in #48b from the 1994 and
2001 census for either colobus or mangabey.
48b Kulesa East As above.
49 Kulesa West 1 The mangabey troop recorded in this forest in 2001 may have moved to
forest patch #46.
50 Kulesa West 2 No troops were found here previously or during the current census.
53 Wema West 1 After mapping, we recognise that this is not the location of forest #53.
The forest should be located further south. One troop of red colobus had
been seen in forest #53 in 1994 but not in 2001.
54 Wema West 2 Though this patch has not decreased considerably between the 1994
and 2005, no troops at all were observed.
55 Wema West 3 One troop of colobus was observed which hadn’t been seen in 2000 or
2001.
56 Wema East 1 Patch #56 has reduced in size markedly from 22 ha in 1994 to 4 ha in
2005. Likely due to the massive human activity, mangabeys appear to
have moved from patch #56 to #69 as in earlier censuses, troops were
found in #56 but not #68 however in later census work, the reverse is
true.
57 Wema East 2 Two of these small patches have been reduced to isolated trees.
58 Hewani West 1 This was by far the most interesting forest patch. Monkeys abound here.
Colobus were more than double the numbers observed in 1994 from
three to seven while mangabey numbers increased from two in 2000 to
three groups. Of all the forests, forest #58 shows a clear trend of
increasing troop numbers over time.
59 Hewani East 1 This patch has a core area of forest and is surrounded by mango trees
with much human activity. Only the forest area was censused.
60 Hewani East 2 In 1994, there was one troop of colobus in each forest – #60 and #61.
This census showed that perhaps the troop from #61 has now moved to
#60 though the second troop was not recorded during the 2000 or 2001
work. #60 and #61 are separated by a gap of grass and bushland.
61 Hewani East 3 As above
62 Hewani West 2 This forest is completely gone along with one troop each of colobus and
mangabey both seen in 2000 but not in 2001 or during this study.
63 Hewani South
1
64 Hewani South
2
65 Bvumbwe
North
66 Bvumbwe
South
This patch shows a progressive decrease in colobus troops from three in
2000 to 1 in 2001 and zero in 2005.
Strangely, the 10-13 groups of colobus sighted in 1994 were not found.
Instead only four groups were seen in 2001 and one troop in 2005.
Mangabeys have maintained a constant level of four troops since 1994.
One mangabey troop seems to have moved into this patch prior to 2001
and still remains. Little decrease in forest area was seen since 1994.
From our mapping, this forest appears to be further south that the field
map we were using. Could the field map be misreported as we did not
see any other forest in the vicinity? Regardless, there were no colobus or
mangabey previously reported in this forest.
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