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Monkey-dung study offers clues about land-use, wildlife ecology
Jim Barlow,
Life Sciences Editor
217-333-5802; jebarlow@uiuc.edu
4/6/06
|
CHAMPAIGN, Ill.
— Fecal matter of red colobus monkeys collected in western Uganda
has yielded a wealth of knowledge about human land-use change and wildlife
health and conservation. The main lesson, researchers say, is that the
intensity of tree removal translates directly to parasite populations
and the risk of infection of their hosts.
In an effort to glean predictive power out of years of research on the
effects of forest fragmentation on various species and ecological processes,
researchers looked at nine differently fragmented regions of forests
located in what is now agricultural landscape just west of Kibale National
Park, in the foothills of the Ruwenzori Mountains. Within these regions,
they focused on populations of red colobus (Piliocolobus tephrosceles)
monkeys and the presence of strongyle and rhabditoid nematodes.
For two years, Thomas R. Gillespie, a professor of pathobiology in the University of Illinois College
of Veterinary Medicine, and Colin A. Chapman, an anthropologist
at McGill University in Canada, surveyed the monkeys and determined
nematode levels by examining 536 colobus fecal samples. Their study
appears in the April issue of the journal Conservation Biology
Gillespie is co-director with Illinois pathobiology colleague Tony Goldberg
of the Kibale EcoHealth Project, a flagship program of the multidisciplinary
U. of I. Earth
and Society Initiative on Emerging Disease & Ecosystem Health.
Red colobus are one of the most endangered African colobine species.
The two groups of nematodes have been documented to infect red colobus
and have the capacity to cause gastrointestinal problems that can be
fatal.
Gillespie and Chapman sorted through nine potential factors, including
physical and biological attributes.
They concluded that the degradation of the forest and human presence,
as measured in stump density, strongly influenced the prevalence of
parasitic nematodes. Infection risk, they reported also was higher in
the fragment with the highest stump density than in the fragment with
the lowest stump density.
“Our results provide evidence that an easily measured index such
as the number of stumps in a given area can be used to predict the degree
to which a fundamental ecological process – host-parasite dynamics
– can be altered by human disturbance,” Gillespie said.
“We think that this pattern is likely to be common in disturbed
areas and may represent an unrecognized threat for the conservation
and management of various habitats.”
Gillespie, who also holds appointments in the anthropology department and the Program
in Ecology and Evolutionary Biology at Illinois, and Chapman, also
a researcher for the Wildlife Conservation Society, were part of a team
that last year reported that selective-logging practices in the region
had changed the ecological balance for three primate species. The red-tailed
guenon, they noted in the Journal of Applied Ecology, is still a primate
in decline. They also reported high levels of parasitic infections in
the guenons in the heavily logged areas.
The parasites being monitored in their studies occur at high frequency
in human populations in the logged region, but are absent from colobus
species within Kibale National Park, where people and primates interact
less frequently, Gillespie said.
Physical factors considered in the new study included size, location
and landscape of each of the nine fragmented regions, while biological
factors in the mix were tree diversity, tree density, stump density
and overall colobine density. Colobines are leaf-eaters that live in
groups of five to 300 individuals, and they depend on forest cover to
survive.
The National Center for Environmental Research, U.S. Environmental Protection
Agency, National Science Foundation, Ford Foundation and Wildlife Conservation
Society supported the research. Permission to conduct the research was
given by the Uganda National Council for Science and Technology and
the Uganda Wildlife Authority.
