Tana Delta Irrigation Project, Kenya: An Environmental Assessment

Rehabilitation of the Tana Delta Irrigation Project, Kenya: An Environmental Assessment.
67 Lango La
Simba
One of the “old channel forests”. Previously this forest had one troop of
colobus, but during this survey, only one solitary adult was seen. The
other “old channel forest”, Hewani South 2 (#64) also had a reduction in
colobus numbers. Further census will show if indeed there is a trend
between loss of colobus in this type of forest as has been seen in
senescent and dying forests #30, 33, 41, 45, 51, 52 along Channel 1
(Butynski and Mwangi, 1994).
This forest had a high buffalo population. There is a possibility that
troops were missed by teams looking more closely for buffalo than for
monkeys though all teams had been increased from two to four members
to increase the number of people looking for both buffaloes and
monkeys.
68 Wema East 4 Curiously, mangabeys have not been previously sighted in this large
forest until this survey. The move of a troop to this forest from nearby
#56 which had steady sightings of mangabeys until 1989.
69 Mitapani South
1
70 Mitapani South
2
Unknown forest
Four elephants in this forest. Though four transects were started, only
one was completed. One mangabey troop was sighted. This group is
probably genetically isolated from the main concentration of mangabeys
to the north.
This forest was very difficult to find due to the change of the river course
and the lack of canoes to transfer the team to the other side. Therefore,
this forest was not censused however in the 2000 and 2001 censuses,
neither red colobus nor mangabey were observed.
Although this forest is not on the original list of forests to census, we
observed a group of colobus while we were in the area.
Status and Distribution of Sykes Monkeys and Yellow Baboons
Tana River sykes monkey (Cercopithecus mitis albotorquatus) and yellow baboons (Papio
cynocephalus cynocephalus) were observed throughout the census area. Nineteen troops
and one solitary adult of sykes and twelve troops of baboon were recorded. Other groups
were seen outside forest patches. Due to the inconsistency of counts of individuals, this
information was not collected for either sykes or baboon.
RECOMMENDATIONS
In the light of the survey carried out and the subsequent observations, the following brief
recommendations are made:
1. Assessments should be made on the two groups of colobus in the northern section of
the census area to determine their long term survival risk and to review potential
management strategies to incorporate them into the main population area depending
on appropriate available forest habitat.
2. Forest #58 and #64 are important for mangabeys as they are the only forests with
more than one troop (three and four respectively), only #58 had significant troop
numbers of both mangabeys and colobus making it the most crucial forest in terms of
requirements for conservation.
3. An assessment should be made to establish the suitability of erecting colobridges
between isolated trees, between forest patches and over the Tana River to provide
habitat corridors. Since 1997, colobridges have been successfully providing habitat
connectivity in the Diani area (150,000 crossings per year for 22 colobridges). This
could be an additional tool in developing corridors at the early stage, and for enabling
connectivity between forest patches across barriers such as the Main Canal, Tana
River and Main Access Roads.
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