Roads have far-reaching impact on chimpanzees

Date:
September 15, 2021
Source:
University of Exeter
Summary:
Roads have a negative impact on chimpanzee populations that can
extend for more than 17 km, new research shows.



FULL STORY ========================================================================== Roads have a negative impact on chimpanzee populations that can extend
for more than 17 km, new research shows.


==========================================================================
A team led by the University of Exeter examined the impact of major
and minor roads on wild western chimpanzee numbers in the eight African countries in which they live.

The impacts extended to an average of 17.2 km (10.7 miles) from major
roads, and 5.4 km (3.4 miles) from minor roads.

Chimpanzee population density drops consistently from the edges of these
areas to a lowest value at the roads.

The situation in untouched areas is hard to assess because less than five
per cent of western chimpanzees' range is outside the "road-effect zones" identified in the study.

The paper is published in the journal Conservation Letters, and the
research team also included Concordia University in Montreal (Canada)
and the Potsdam Institute for Climate Impact Research.



========================================================================== "Western chimpanzees were once widespread across West Africa, but
the species has declined by 80% in the last 20 years and is currently classified as critically endangered," said Balint Andrasi, who led the
study as part of a masters in Conservation Science and Policy at Exeter.

"The human population in West Africa is growing rapidly, and
chimpanzees face mounting pressure from the expansion of settlements
and infrastructure.

"Previous research suggests that roads dramatically reduce western
chimpanzee numbers, rather than simply displacing the animals.

"Just 4.3% of their range remains unaffected by roads, so they don't
have anywhere else to go, and in any case migration over long distances
is uncommon.

"Western chimpanzees are highly territorial, so attempting to move
could lead to conflict with neighbouring groups." The study did not
directly investigate the reasons why roads affect chimpanzee numbers,
but the researchers highlight several possible explanations.



==========================================================================
As well as direct impacts like roadkill and noise, they say roads open
up unexploited areas to industries such as mining and agriculture which
often reduce or remove forest habitats.

Roads can also restrict chimpanzee movements, dividing populations and
causing genetic isolation.

Hunting is a persistent threat to western chimpanzees, and roads provide
easier access for hunters.

"When roads appear, so do all sorts of human activities," Andrasi said.

Regulations in many countries require that wildlife should be considered
before new roads are built, but until now the size of the impact area
affecting chimpanzees had not been estimated.

The researchers hope their findings will help to bring about more
effective guidelines to mitigate road impacts.

"This is the first time this analytical approach has been used to
understand the impact of roads on nonhuman primates, and the results
are shocking," said Dr Kimberley Hockings, of the Centre for Ecology
and Conservation on the University of Exeter's Penryn Campus in Cornwall.

"We hope these findings will ensure the true costs of infrastructure development on the critically endangered western chimpanzee are fully considered by policy makers.

"Our great ape cousins face so many threats, from habitat change to
hunting to disease.

"The impact of infrastructure development is much larger than I ever anticipated and is truly worrying.

"But we can't give up. We must do everything we can to ensure their
continued survival. I can't imagine a world where humans are the only
great apes left." The study combined data on western chimpanzee density
with road routes across the range inhabited by the species, which spans
Ghana, Guinea, Guinea Bissau, Ivory Coast, Liberia, Mali, Senegal and
Sierra Leone.

========================================================================== Story Source: Materials provided by University_of_Exeter. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Balint Andrasi, Jochen A.G. Jaeger, Stefanie Heinicke, Kristian
Metcalfe,
Kimberley J. Hockings. Quantifying the road‐effect zone for
a critically endangered primate. Conservation Letters, 2021; DOI:
10.1111/ conl.12839 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210915085839.htm

--- up 1 week, 6 days, 8 hours, 25 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)