Chimpanzees can adapt in human habitats better than expected, by including human-cultivated foods into their diets and becoming more aggressive to deal with threats from humans, a new study has found.
Researchers spent 15 months carrying out 'genetic censusing' to provide an accurate method for counting chimpanzees in an unprotected human-dominated corridor of villages, agricultural lands and natural grasslands, between the protected Budongo and Bugoma Forest Reserves in Uganda.
This involved collecting 865 chimpanzee fecal samples across 633 square kilometres and genetically analysing them to identify the presence of 182 different chimpanzees.
They then estimated the total population size of the area to be either 256 or 319 chimpanzees, depending on the calculation used.
These figures are more than three times greater than a previous estimate of around 70 chimpanzees based on small-scale nest count surveys.
"Our results demonstrate a much larger population than previously estimated in this region," said lead author Maureen McCarthy from University of Southern California, US.
"This is very surprising given the fragmentation of forests in this region and the high human population density. Chimpanzees, therefore, appear surprisingly resilient and can survive even in degraded habitats if they are not hunted," McCarthy said.
"However, their future survival remains uncertain if protection is not afforded to them and habitat loss continues unabated," McCarthy said.
The substantially higher estimates reflect the improved accuracy of the genetic censusing approach over previous estimates, and not an increase in population of chimpanzees, the researchers said.
The surprising levels of chimpanzee survival in a fragmented human-dominated habitat are also likely aided by their behavioural flexibility.
This includes incorporating new (often human-cultivated) foods into their diets and adopting more aggressive behaviours to mitigate human threats.
"Our study demonstrates that even unprotected and degraded habitats can have high conservation value," McCarthy said.
"Though national parks and other protected areas are typically prioritised in conservation planning, unprotected areas should also be considered vital for conservation if they are highly valuable as wildlife corridors that harbour endangered species and maintain gene flow among larger populations of such species," McCarthy said.
The study was published in the journal BMC Ecology.