Nav: Home

Scientists estimate: Half of tropical forests under hunting pressure

May 14, 2019

Hunting is a major threat to wildlife in tropical regions. A previous study led by Ana Benítez-López at Radboud University, showed that bird populations declined on average by 58 percent and mammal populations by 83 percent in hunted forests. The same group of scientists has now been able to map the expected decline for each mammal species across all tropical forests.

4000 mammal species mapped

The scientists base their conclusions on data collected over the span of 40 years on the numbers of mammals in hunted and unhunted areas. Based on these numbers, they estimated the impact of hunting on approximately 4000 mammal species in the tropics. The populations of medium sized mammals, such as monkeys, showed an average decline of 27 percent. The average decline in large mammals, like jaguars, leopards, elephants and rhinos is even bigger: more than 40 percent. "Hunters target primarily large-bodied species because they provide relatively large meat yields and commercially valuable by-products such as horns and bones. In addition, large mammals reproduce at slow rates, which means that it takes longer for their populations to recover when exploited", Ana Benítez-López explains.

Where are species more threatened by hunting?

According to the study, more than half of tropical forests are under hunting pressure. Benítez-López: "Even forests that are considered intact according to satellite images - in which there is no visible deforestation or logging - could be partially defaunated." The scientists identified hotspots where hunting pressure is highest. "We mapped the tropical areas and for each location estimated how severe the impact of hunting on mammals is. We found the biggest declines in Western Africa, with more than 70 percent of population reduction. Our calculations show that even in protected areas mammal populations could be under hunting pressure, particularly in Western and Central-Africa, and South-East Asia."

Take into consideration in retaining biodiversity

Hunting is not the only driver of animal decline in tropical landscapes. Other drivers are habitat destruction and fragmentation by deforestation and logging. The abundance decline of mammals may have profound implications for ecosystem functioning. Benítez-López: "Hunting of carnivores may lead to an increase in herbivores with negative consequences for the vegetation whereas the hunting on species that feed on fruits and disperse their seeds can have negative consequences on forest regeneration". In addition, some rural communities are dependent on wild meat for their food supply, but their main sources of protein may be slowly disappearing. "Hunting effects were to this point not considered in large-scale biodiversity assessments and our results may help to fill this gap and to eventually produce more representative estimates of human-induced biodiversity loss. Further, now we have identified hotspots of hunting that require monitoring and conservation", Benítez-López concludes.
-end-
Publication

Ana Benítez-López, Luca Santini, Aafke M. Schipper, Michela Busana, Mark A. J. Huijbregts. Intact but empty forests? Patterns of hunting-induced mammal defaunation in the tropics. PLOS Biology. DOI: 10.1371/journal.pbio.3000247

Radboud University Nijmegen

Related Tropical Forests Articles:

NASA examines potential tropical or sub-tropical storm affecting Gulf states
NASA's Global Precipitation Measurement mission or GPM core satellite passed over a developing low pressure area in the Gulf of Mexico and gathered two days of rainfall and storm height information.
Lianas stifle tree fruit and seed production in tropical forests
Vines compete intensely with trees. Their numbers are on the rise in many tropical forests around the world.
'Narco-deforestation' study links loss of Central American tropical forests to cocaine
Central American tropical forests are beginning to disappear at an alarming rate, threatening the livelihood of indigenous peoples there and endangering some of the most biologically diverse ecosystems in North America.
Long-term fate of tropical forests may not be as dire as believed, says CU Boulder study
Conventional wisdom has held that tropical forest growth will dramatically slow with high levels of rainfall.
Climate policies alone will not save Earth's most diverse tropical forests
Many countries have climate-protection policies designed to conserve tropical forests to keep their carbon locked up in trees.
Smart road planning could boost food production while protecting tropical forests
Conservation scientists have used layers of data on biodiversity, climate, transport and crop yields to construct a color-coded mapping system that shows where new road-building projects should go to be most beneficial for food production at the same time as being least destructive to the environment.
Road planning 'trade off' could boost food production while helping protect tropical forests
Scientists hope a new approach to planning road infrastructure that could increase crop yield in the Greater Mekong region while limiting environmental destruction will open dialogues between developers and the conservation community.
Natural regeneration may help protect tropical forests
A new article summarizes the findings of 16 studies that illustrate how natural regeneration of forests, a low-cost alternative to tree planting, can contribute significantly to forest landscape restoration in tropical regions.
NASA sees Tropical Storm Nicole going 'extra-tropical'
Tropical Storm Nicole was becoming extra-tropical when the NASA-NOAA Suomi NPP satellite passed over it from space and captured a visible picture of the storm.
Can't see the wood for the climbers -- the vines threatening our tropical forests
Woody climbing vines, known as lianas, are preventing tropical forests from recovering and are hampering the ability of forests to store carbon, scientists are warning.

Related Tropical Forests Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".