The socioecology of interspecific associations among the monkeys of the Mwanihana rain forest, Tanzania: a biogeographic perspective - Biogeography and Ecology of the Rain Forests of Eastern Africa - page 278

now been described for a number of taxonomic
groups found in the Easten Arc Montane Forest
Chain.

Acknowledgements
This project began as part of a combined effort by
several botanists and zoologists to characterise the
wildlife of the Uzungwa forest. The project was
iniiated by Alan Rodgers and Jon Lovett, with the
support of the (then) World Wildlife Fund and
the National Geographic Society. Permission to
carry out this study was granted from the
Serengeti Wildlife Research Institute, the
Tanzanian National Parks, the Tanzanian
Deparment of Forestry, and the Tanzanian
Naional Scieniic Research Council. Jon Lovett
provided valuable assistance in plant idenifica-
ion, as well as informaion on plant species dis-
tribuions across Central Africa. Assistance on
plant identiicaions also was provided by the
Botany Department of the University of Dar es
Salaam. We are paricularly grateful for the help
of several field assistants, including Alison Star-
ling, Preston Hardison, Virginia Bound, Ayoub
Njalale, Agricola Lihuru, and Langson Kisoma.
Special thanks go to Alison Starling, without
whom this project never would have begun, and to
Mpishi Jon Lemani, who bakes the finest forest
bread in all of Tanzania. Valuable comments on
the manuscript were provided by Carolyn Crock-
ett, Jon Lovett, Faina Mturi Omari, Gordon
Orians, Rudy Rudran, Tom Struhsaker, Lauren
Marra Wasser, and two anonymous reviewers.
This research was supported by grants to the
author from the Naional Geographic Society and
the World Wildlife Fund.

Summay

Grouping and foraging pattens were studied
among the Uhehe red colobus (Colobus badius
gordonoum), the black-and-white colobus (.
angolensis palliatus), the Sykes monkey (Cercopithe-
cus mitis moloneyi) and the Sanje crested
mangabey (Cercocebus galeitus sanjei) in the
Mwanihana Forest of the Uzungwa Mountains,
Tanzania. The Uzungwa Mountains are part of
the Eastern Arc mountain chain - a string of
ancient, biogeographically isolated, forested
mountains that stretch across easten Tanzania.
All primate species in the Mwanihana Forest were
found to associate interspecifically during the 11-
month study period. However, the highest rates of
interspeciic associaion were ound between the
two colobines (>50% of their sighings; 25% of
all monkey sighings). The red and the black-and-
white colobus rarely associate with one another
wherever else they co-occur. Overlap in plant
food species among the colobines in the Uzung-
was also was relaively high compared with other
locaions, whereas dietary overlap at the part per
plant species was comparatively low. These con-
diions sharply contrast with those between the
Sykes monkey and the mangabey; both of these
species show strong preferences for fruit
throughout their range. Accordingly, their dietary
overlap in the Mwanihana was high at plant spe-
cies as well as plant part levels; they also rarely
formed mixed species associaions with one
another. Results suggest that dietary divergence at
plant part level may have reduced compeition
between the Uzungwa colobines, while preserving
their tendencies (through high plant species over-
lap) to feed in the same species of ree. Such
dietary pattens may have resulted from a com-
paraively lower availability of potential plant food
species in the biogeographically isolated Uzungwa
Mountains compared with elsewhere. The possi-
bility that these events represent a form of charac-
ter displacement is discussed.

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