Monkey Moves 
Among western red colobus monkeys, females have the freedom to 
transfer from troop to troop. The males generally don V 
by E. D. Starin 
I had spent weeks trying to observe 
the shy, predominantly arboreal west- 
ern red colobus monkey in The Gam- 
bia’s Abuko Nature Reserve, and still 
could not understand what type of so- 
cial organization they possessed. For 
much of the time I saw only a foot here, 
a tail there, and then a mass of black- 
and-reddish bodies fleeing through the 
forest canopy and leaping out of sight. 
After weeks of not always being able to 
differentiate females from males, of not 
knowing whether I was watching one 
troop or two, I was about to give up try- 
ing to concentrate on social behavior 
when one day the colobus stopped run- 
ning and hiding and allowed me to fol- 
low them throughout their home range. 
Red colobus monkeys are spread 
throughout equatorial Africa, in a vari- 
ety of habitats from The Gambia to 
Zanzibar. In The Gambia, they inhabit 
riverine forest, mangrove swamp, var- 
ious types of savanna, village perime- 
ters, and infrequently, residential gar- 
dens. For the past forty-two months, I 
have been studying the socioecology of 
the western red colobus monkey ( Colo- 
bus badius temmitickii) in the Abuko 
Nature Reserve. The reserve, located 
about twelve miles from the capital, 
Banjul, comprises some 263 acres of 
Aggression is infrequent within 
a troop of western red colobus. 
Moments before this photograph was 
taken, this adult female expressed 
a threat, but quickly changed to 
the expression of appeasement seen 
on her face here. 
riverine forest; shady, dense raffia palm 
swamp; sunny, swampy clearings; and 
various types of savanna. Scattered 
throughout the reserve’s swamps are 
pools inhabited by both Nile and dwarf 
crocodiles. 
The colobus share the reserve with 
two other monkey species: the red patas 
and the green vervet. Although patas 
and vervets eat some of the same foods 
as the colobus, there is probably little 
competition. The patas monkeys live in 
harems and spend most of their time on 
the ground in the savanna zones and 
croplands that surround the reserve. 
Foraging through leaf litter, patas ap- 
pear to consume insects and small rep- 
tiles, such as skinks — food sources the 
thumbless colobus would find difficult 
to harvest. The vervets, on the other 
hand, are everywhere, utilizing all lev- 
els in all habitat zones — from digging 
holes in the savanna to sleeping, feed- 
ing, and resting high in the riverine can- 
opy. Young vervets have even been seen 
playing and possibly feeding in pud- 
dles. Although they eat some of the 
same fruits, flowers, stems, and young 
leaves as the colobus, vervets also feed 
on items not eaten by the colobus: in- 
sects, mushrooms, tender grass shoots, 
palm-nut kernels, tubers, and red ant 
nests. Although classified as folivores, 
the Abuko colobus feed on large 
amounts of fruits, flowers, and seeds. 
They even consume the odd gall and 
appear to relish the soil from aban- 
doned termite trails. 
The vervets and patas have an essen- 
tially neutral relationship with the co- 
lobus. In fact, the patas and colobus 
rarely meet. In forty-two months, I saw 
patas in the main study troop’s home 
range on only fourteen occasions. Ver- 
vets and colobus, however, do occa- 
sionally interact. (When a colobus and 
a vervet of the same size meet on a path, 
the colobus usually takes precedence. 
Often, if a small colobus is threatened 
by a larger vervet, the colobus will ei- 
ther ignore the vervet or it will squeal 
until a gang of its older associates ar- 
rives and chases the vervet off.) While 
one-and-a-half to three-year-old female 
colobus frequently seek out nearby ver- 
vets for grooming and resting sessions 
and have even attempted to kidnap 
newborn vervets from their mothers, 
young male colobus tend to ignore the 
vervets. One young male colobus, how- 
ever, spent more than a year as a mem- 
ber of a vervet troop while he shadowed 
colobus troops. 
There are probably few carnivores in 
the reserve capable of taking a colobus. 
The Nile crocodile and the African py- 
thon do prey on them, however. And 
while I have never seen colobus being 
attacked by birds of prey, they give 
alarm calls at most large birds; one 
adult female and her two-year-old son 
even gave alarm calls at a falling three- 
foot-long leaf, and an adult male gave 
an alarm call at a low-flying helicopter. 
There is a tremendous amount of in- 
dividual variation in colobus facial fea- 
tures, hair color, postures, and vocali- 
zations — traits that the colobus prob- 
ably use to recognize each other. And 
what I found most intriguing were 
the individual behavioral differences, 
which in many cases do not appear to 
be related to gender. After I gradually 
learned to recognize individuals, it be- 
came clear to me that the Abuko colo- 
bus do not live in compact troops. 
Rather, they exhibit a form of “fusion- 
fission” social organization, that is, like 
E D Stann 
37 
