other mammals

TAKE A LOOK AT SOME OF OUR RECENT WORK

 

trail cam studies

Trail cams are sensitive cameras that respond to any movement in front by capturing an image or video of the moving object.  They are extremely useful in assessing mammal faunas in dense vegetation or where animals are very elusive (for example where hunting pressure is intense).  Over the past 10+ years, we have monitored key forest sites in The Gambia and surveyed most of the protected areas using trail cams.  This has helped us make several important discoveries and revealed information that has helped with the management of individual sites.

Acrobatic otters and cryptic cats

Cape clawless otters (Aonyx capensis) occur in The Gambia, but their distribution and abundance are poorly understood.  One student group was determined to capture an otter's image and placed a trail cam above a site regularly used by territorial otters.  Male otters mark their territory nightly by leaving spraints (droppings perfumed by excretions from the anal glands that other otters can individually identify).  The next morning the students were disappointed when they found no images had been taken even though the otter had marked its territory.  The camera's smell was clearly new to the otter, which responded by marking it with a spraint - on top!.. To achieve this, the otter must have performed a handstand to make its deposit on the camera, attached to a tree around 1m above the ground.  We asked the students if the camera had “captured” any other animals, and they told us the only thing was a cat, probably from the nearby village.  When we checked the images, we did find a cat, but it had very long limbs and distinctive ear tufts.  It was the first year of a species that had not been seen for so long in The Gambia that it was thought to be extinct - a Caracal (Caracal caracal). The following year, with the help of a goat's leg, we also got a video of another very rare cat, the Serval (Leptailurus serval).

student dissertations

Project Wild Gambia provided a decade’s worth of camera trap images from five West Gambian forests to two students who attended the field course to collect their own camera trap data. These students discovered the presence of a fascinating species (not previously known to The Gambia), which we are helping them report in a scientific paper. The paper will also summarise our findings over 10 years of forest surveys, during which we have added to our understanding of the distributions of many species. These species include civets, genets, mongooses, porcupine (which we’ve discovered are especially fond of potatoes as bait) and African palm civet (Nandinia binotata) - a species whose known distribution we doubled from 2 sites to 4 from our project research.

The images collected by the students also revealed the first bushbaby to have ever been caught on a camera trap. Bushbabies are an arboreal species, which may explain why they are not usually detected. We intend to set up arboreal camera traps to test this and hopefully provide further insight into their behaviour and distribution. Our surveys of Bushbabies (using eyeshine surveys on foot or from the back of open-top Land Rovers) have shown an interesting pattern of distribution along the coast; they are relatively common from Kartong to North of Sanyang but are then mostly absent going North until again being common on the North Bank.  We have ongoing research looking into what ecological factors determine this distribution.  

The dissertations students also conducted habitat assessments to compare the effects of environmental variables on Gambian mammals. The study found that five of the seven variables measured had a significant relationship with the number and rarity of mammals recorded. This suggests preferences that can be incorporated into management strategies for each forest, including species choices for tree nurseries and the impact of hunting, grazing, etc.

Our trail cams continue to collect data when we are not there, providing coverage all-year-round.  They also act as our eyes in the forest, detecting grazing, human disturbance, wood extraction, and illegal hunting.  We have used our images to inform village elders etc., of the activities in their forests, allowing them to take appropriate action.  For example, the image below was used by a village committee to take out an injunction against the monkey hunter, banning him from entering their forest.

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Dissertation student measuring the DBH (diameter at breast height) of a tree

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