Apes Dismantle Snares
Bushmeat traps are unfortunately ubiquitous contraptions in central Africa. Most are homemade and illegal. Not only are the traps deadly to their intended prey (antelope, wild boar, etc) but also to chimpanzees and gorillas. They are currently one of the greatest threats to gorillas. But there is hope that fewer apes will be caught in the traps, as both chimps and gorillas have been learning to deactivate the snares. On July 19th a group of gorillas in Rwanda were witnessed deactivating a snare, just two days after a snare killed a young female in their group.
John Ndayambaje, a field data coordinator for the Dian Fossey Gorilla Fund was working in Volcanoes National Park, close to a group of mountain gorillas when he noticed a snare very near the group. Amazingly, as he went to approach the snare to deactivate it (to protect the gorillas), the Silverback of the group pig-grunted (a vocalization of warning) at the Fossey employee to stay back, and immediately two juveniles together with a blackback (a teenage silverback) ran toward the snare and together pulled the branch that was used to hold the rope and deactivated the trap. The gorillas saw another snare nearby and just as swiftly destroyed the branch and pulled the rope out of the ground.
Although Silverbacks have been observed deactivating snares in the past, this is the first time anyone has witnessed the younger gorillas taking on this duty.1
“We knew that gorillas do this but all of the reported cases in the past were carried out by adult gorillas, mostly silverbacks,” said Veronica Vecellio, gorilla program coordinator at the Karisoke Research Center. “Today, two juveniles and one blackback from Kuryama’s group worked together to deactivate two snares and how they did it demonstrated an impressive cognitive skill.”2
The snares consist of a loop of rope or iron wire hidden on the ground under brush or dirt or are dangled just above the ground in a pathway. The wire or rope is attached loosely to a bent back branch, sapling or stalk of bamboo and also firmly attached to a nearby tree. When an animal steps into the loop, the branch springs back up and pulls the loop tight, causing the trapped animal to be noosed and attached to the tree. If the animal struggles, the noose becomes ever tighter.
To disable the snare, the gorillas were observed breaking the bent branch, thus releasing the tension on the rope. Sometimes they also pull the rope out of the ground.
Although gorillas are good at dismantling the traps prior to getting caught in them, once they are snared, they are injured as they fight to free themselves. And even if they can cut through the rope or a human tracker cuts them free, they have difficulty loosening the remaining noose or wire which can continue to cause injury. Here, Inkumbuza, a three-and-a-half-year-old mountain gorilla has been snared. Her family members inspect the rope. Read the story here: gorilladoctors.wildlifedirect.org
A wound from a wire snare. Read the story here: gorilladoctors.wildlifedirect.org
Only 480 mountain gorillas remain and they live in the Virunga Massif, a wilderness area encompassing Volcanoes National Park in Rwanda, Virunga National Park in the Democratic Republic of Congo, and Mgahinga National Park in Uganda. A second, smaller mountain gorilla population lives in Uganda’s Bwindi Impenetrable National Park. On average, anti-poaching patrols remove more than 1,500 snares from the Virunga Massif annually.
2012, has seen the death of two juveniles to snares so far. See: Mountain Gorilla Veterinary Project.
In western Africa a similar story is taking place, although most chimpanzee groups have yet to figure out how to dismantle snares, one group in the Bossou region of Guinea has. Japanese primatologists Mr Gaku Ohashi and Professor Tetsuro Matsuzawa observed a group of five male chimps deactivating and attempting to deactivate snares along a path. Although gorillas are never the intended prey in bushmeat traps, chimps are. The snares the chimps are deactivating are intended for them.3
Many chimps are killed and maimed each year in snares, however very few snare injuries are reported in the Bossou region and after the Japanese scientists observations, we now understand why. The scientists observed six different occurrences were the chimps either grasp the snare stick and shake it violently or hit the arched sapling to spring it. In all cases, the chimps avoided touching the dangerous part, the wire loop.3
Watch a BBC Video of the chimps deactivating a snare here: news.bbc.co.uk
Another newly observed behavior is that of chimp hand holding. It appears certain groups of chimpanzees hold hands while grooming one another. Because certain troops have their own peculiar way of holding hands (some palm to palm, some clasping wrists, etc.) and because it is behavior not practiced by every group, it is considered a cultural behavior. See the study here: spb.royalsocietypublishing.org
LiveScience story: www.livescience.com
1) Fossey News Release: gorillafund.org/news--events/pr_120721
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the photographer set up to get the shots...
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