Gráinne McCabe, Head of Field Conservation and Science here at Bristol Zoological Society, marks Earth Day by recalling her recent visit to Tanzania, searching for the elusive Sanje mangabey monkey.
It’s 5 a.m. when we wake in the forest. The tent is still dark as the sun has yet to rise above the mountains that loom over the valley. The forest isn’t quiet by any stretch of the imagination - the insects are still singing loudly and it won’t be long before the birds start to wake.
I unzip my tent and crawl out into the humid air beneath the tall ancient trees. We have to be on the trail in the next 30 minutes if we are to reach our destination in time, so it’s a very quick breakfast around the campfire, with thick coffee and leftover beans and rice from the night before, and then we are off.
Deep among the dense forest we could be anywhere - the hot, humid forests of Panay Island in the Philippines, the dry Sambirano region of northwestern Madagascar, the dense rainforest of the Congo Basin in Equatorial Guinea, the wet tropical forest of the Central Valley of Costa Rica, each one a flagship conservation project site of the Bristol Zoological Society.
But this is Tanzania, the remote and little-explored Udzungwa Mountains, also known as the Galapagos of Africa for its high level of biodiversity and number of species found here and only here. We are on the trail of the elusive Sanje mangabey monkey. I started my work here more than 10 years ago, examining whether female mangabeys could keep their babies alive if they conceived at a time of year with little food available. The answer was, sadly, they couldn’t.
The research got me thinking about how fragile their existence is in these valleys. Sanje mangabeys are endemic to this region; they live here within only 377km2. Previous estimates from more than 17 years ago suggested only 4,200 animals remained. They are found in two forest blocks, one a well-protected national park; the other, an unprotected nature reserve with illegal hunting, logging and forest clearance for agriculture happening at a rapid rate. These forests are separated by over 100 km of agricultural land – a vast distance almost impossible for a monkey to cross in search of mates or food.
I have come back to the mountains this time to see how many monkeys may be left in a study led by one of my PhD students and carried out by our incredibly dedicated and hard-working Tanzanian field team.
Sanje mangabeys live in large groups – some can have more than 70 individuals. In the morning, the dominant males in each group will make a very distinctive loud call known as a ‘whoop-gobble’. This strange sound (part chimpanzee call - part turkey gobble), can travel a long distance through the valleys, and acts as a spacing mechanism, warning other groups that might be in the area that they are here. Such calls let monkey groups avoid what could become very dangerous inter-group encounters that could lead to fights over territory. Luckily for us, these calls can also allow us to easily count the number of groups that we hear in each valley – giving us an accurate group number for each forest.
So after breakfast, we hike up to the ridge of the mountain in the early light to wait. And before long, we hear them. Two groups - the males’ calls echoing down the valley, their early morning conversation ringing out as we note the direction, the distance and angle to the call.
Later, back in the UK, we will run the numbers and find some alarming results – almost a 30% decline since the early 2000s. But strikingly, the national park population seems to be holding steady, a testament to the power of actively protected areas.
The numbers in the other forest fragment where they are found are more concerning, and in response we are now joining forces with other partner conservation organisations in the region to fund wildlife patrols here. This is just one conservation project of many driven by a collective passion and determination from my team at the Society, as well as the local communities we engage with.
Our conservation staff have achieved some incredible things in recent years. We’ve established a sustainable palm oil project. We’ve helped to rescue, rear and release more than 5,700 African penguin chicks off the coast of South Africa. We’ve trained 36 members of the Conservation Service in Bénoué National Park, northern Cameroon, in the use of drones for monitoring illegal activities within the home range of the Critically Endangered Kordofan giraffe. We have supported more than 30 Malagasy researchers undertaking conservation science projects on lemurs and other animals threatened with extinction in northern Madagascar.
And closer to home in and around Bristol, we have cleared more than 215km of river bank of invasive non-native species with the help of more than 11,000 hours of volunteer time. In 2018 alone, more than 11,000 people engaged with our Avon Gorge and Downs Wildlife Project through walks, talks and events. We’ve established 17 safe refuge sites for the native white-clawed crayfish, currently under threat of extinction from invasive species and crayfish plague.
Strengthening protected areas is a key activity of the Society in many of our conservation projects and, from our small base in Bristol, we continue to champion safe and healthy ecosystems to ensure the survival of threatened species around the world. By visiting Bristol Zoo and Wild Place Project, you are also helping us to halt the decline of threatened species like the mangabeys in the Udzungwa Mountains.