Bulletin of the EANHS 27< I ) 
ARTICLES 
THE DECLINE OF ANGOLAN COLOBUS 
MONKEYS COLOBUS ANGOLENSIS 
PALUATUS IN DIANI 
Though not currently listed as threatened, Colatms 
angoleruas ssp pallialus may be at least vulnerable to 
extinction in East Africa Although < ' angolenm enjoys 
an extensive range in central African rainforests, tlir sub- 
species palliatos is restricted to isolated fragmented 
and largely threatened coastal forests of Kenya and 
Toiuania I is current distribution in Kenya includes the 
Shiniba Hills National Reserve. Mwalunganje Forest 
Reserve. Gongoni Forest, and relic forest patches in 
Dtani. Galu Kinondo. RanusL Cluleand Slumoni. lulling 
already disappeared from approximately one third of its 
former range which included Kilifi tTnmra. 19*6) and 
Tsavo West (Estes. 1992), In Tanzania n is found in the 
Usambara mountains, the Selous Game Reserve and 
coastal forests in southern Tanzania la very isolated 
population of C angoUmts in the Maltalc mountains 
nun be a distinct subspecies (Ntshidarf a! . 19X1 n While 
at first glance this handsome black and white monkey It 
easily confused with its better known relalite, llicgucre/a 
( Colobus guerna). which has a similar glossy 
contrasting black and whitc coat, the Angolan colobus 
difTcrs by* having while epaulettes t mantle in (lie guercra k 
long white cheek hairs and ;i white tail tip (fluffy white 
tail in guereza) 
This report refers to a census conducted in Dtani where 
long time residents have noticed a decline in the number 
and sizes of Angolan colobus groups over the past 10 
years or so. Thirty volunteers participated in the primate 
census of Diani that established the population and 
distribution status of this colobus and other priinalc 
species (baboon Papin eynocrphalus. verve! 
Ccrcoplihecus aethiops. and Sykes' monkeys 
Cercopithecus mills albogularls ) 
Seven teams of 4 volunteers searched blocks of foresi 
on the 30* November and 1" of December 1996. The aim 
was to establish a total count of colobus by' groups, 
group s iz es and habitat locations. Other primate species 
groups were also enumerated The area surveyed was 
from the Tiwi River in the north to the Neptune Hotel in 
the south, approximately 9.7 km ! (800 m wide and 12 km 
long), including two kay a forests lying approximately I 
km west Forest blocks were classified as Diani Forest 
modified forest and llie kayos 
A total of 85 pnmale groups were enumerated with 
colobus and Sykes' being the most common (table 1 1 
Hie total population of colobus monkeys in Diani is 
estimated lobe 234 animals based on an average group 
size of 6, Tliree solitary colobus were observed, one 
was a female One bachelor group of three males was 
also observed fie overall density or colobus was 24 
indivtdualsknr ranging from 1 1'lro' in ihe kayas to 72 1 
km- tn Duim foiea Diani Faren occupying only l 5 km' 
(nr 1 54a oflltc urea treasured) contained almost half of 
Ihe pnmale population of Dtani wiih 24 pninale troops/ 
km 1 or 164 monkeysfcnr Almost half of dicse were 
colobus. The Diam ami Ukuoda Karas, containing 
similar dosed forest lo Diani Forest were surprisingly 
deficient in all species of pnmates. while the modified 
areas had more pnmates than the kayas 
Table 1 Group counts for each primate species 
by census block in Diani 
Location Colobus Sykes' Vervet Baboon 
Kayas 3 3 1 0 
Diani Forest 18 17 0 1 
Modified 17 18 6 1 
Total 38 38 7 2 
The EANHS wishes to thank the following for their support: 
Sponsors of the Society 
A. R Gregory 
J.H.E. Leakey 
Drs T Butynski & J. Kalina 
P Colbert 
M. K Minot 
T Lehumbog 
A Forcsii 
S. Collins 
M . Rigby ' 
N. Hcyei 
Dr V Soracn 
J RuparcJ 
N Searle 
t Bt.idlcy Mamu 
Corporate members: 
Elsa Conservation Ti 
Monsanto 
U.TC 
