Her hunger growing, she broke a short branch from a tree, ripped off the side-shoots and leaves, stripped down the bark, and sharpened the end with her teeth. Jabbing this self-made spear into a tree hollow, she struck lucky first time and dragged a screeching bushbaby from its sleeping space. With a few swift blows this chimpanzee had achieved her aim: dinner.
It’s nearly 15 years since scientists first observed western chimpanzees – a critically endangered subspecies of the common chimpanzee – hunting with spears at a site in south-eastern Senegal. Native to western Africa, western chimpanzees (Pan troglodytes verus) are the only chimps known to use spears. They also differentiate themselves by living in caves, sharing food and travelling and foraging at night.
Despite this chimp subspecies being well studied, the data tend to be specific to particular localities. With no central database of findings, it was hard for scientists to compare studies, observe population trends or map out the density distribution of the animals. And these are the kinds of data that conservationists need to make evidence-based decisions on how best to protect the ape and where to prioritize conservation activities.
To remedy this issue, in 2005 scientists established the International Union for Conservation of Nature (IUCN) Species Survival Commission Ape Populations, Environments and Surveys database, or APES, to bring together survey data for all 14 taxa of great apes. Fourteen years later, they are able to show the benefits achieved by sharing data this way, and to demonstrate that similar databases would bring huge conservation benefits to other endangered species.
For western chimpanzees, APES collated 52 datasets collected during separate studies between 2001 and 2015 across nine different countries in West Africa.
“For the first time we were able to model the distribution of western chimpanzee densities across their entire range,” says Stefanie Heinicke from the Max Planck Institute for Evolutionary Anthropology, Germany.
By comparing the chimp data with information on forest loss, the researchers could see that western chimpanzees are highly sensitive to forest loss, and that if a forest shrinks by more than 10% the chimps tend to disappear.
The database has already had an impact, demonstrating that western chimp numbers have declined by 80% since 1990 and providing the necessary evidence for the species to be updated to “critically endangered” on the IUCN’s Red List.
In their most recent publication, in Environmental Research Letters (ERL), Heinicke and colleagues reveal that only 17% of western chimps live in national parks, and 10% of western chimps live within 25 km of four multinational “development corridors” currently planned for West Africa.
“The results from our study can be used to estimate how many chimpanzees would likely be affected by such developments and advise on the locations where population connectivity might already be low and should therefore be avoided by new developments,” says Heinicke.
As well as improving our understanding of western chimps, this database has allowed researchers to get a handle on the distribution of bonobos, central chimpanzees and the western lowland gorilla, providing valuable input to the conservation action plans for these species.
A handful of similar taxon-specific databases are in existence for other taxa, but the researchers argue that rolling out these collaborative databases more widely would have huge conservation value.
“These databases help to fill the gaps in biodiversity data and they provide the level of detail needed for conservation planning,” says Heinicke.
Right now, funding to create such databases is thin on the ground, but Heinicke and her colleagues hope that the value of the information emerging from the APES database will encourage funders to adopt similar programmes for other taxa too.
