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| Hunting and habitat degradation are universal threats to primates across the tropics, thus deciphering
the relative impact of threats on population relative abundance is critical to predicting extinction risk
and providing conservation recommendations. We studied diurnal primates over a period of nearly
6 years in the Udzungwa Mountains of Tanzania, a site of global importance for primate conservation.
We assessed how population relative abundance of five species (of which two are endemic and IUCNEndangered)
differed between two forest blocks that are similar in size and habitat types but contrast
strongly in protection level, and how abundance changed during 2004–2009. We also measured habitat
and disturbance parameters and, in the unprotected forest, evaluated hunting practices. We found significant
differences in primates’ abundance between protected and unprotected forests, with the greater
contrast being the lower abundance of colobine monkeys (Udzungwa red colobus and Angolan colobus)
in the unprotected forest. At this site moreover, colobines declined to near-extinction over the study period.
In contrast, two cercopithecines (Sanje mangabey and Sykes’ monkey) showed slightly higher abundance
in the unprotected forest and did not decline significantly. We argue that escalating hunting in the
unprotected forest has specifically impacted the canopy-dwelling colobus monkeys, although habitat
degradation may also have reduced their abundance. In contrast, cercopithecines did not seem affected
by the current hunting, and their greater ecological adaptability may explain the relatively higher abundance
in the unprotected forest. We provide recommendations towards the long-term protection of the
area. | |
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