- On Zanzibar’s second-largest island, Pemba, lives a diminutive antelope that hasn’t been officially recorded in at least 20 years.
- Its long absence has fueled fears the animal may have been exterminated from Ngezi Forest Reserve by hunters.
- In early December, a group of scientists and conservationists set up camera traps to try to find signs that this subspecies of the tiny blue duiker is still alive.
PEMBA ISLAND, Tanzania — Pemba Island’s Ngezi Forest Reserve, a complex of moist evergreen and coastal forests, mangroves and heathland in the Zanzibar archipelago, is the last refuge of the Pemba blue duiker . But are there any of these tiny antelopes still alive?
Philantomba monticola pembae, or paa wa pemba as it’s known locally, is believed to be a subspecies of the blue duiker (Philantomba monticola), a small antelope widely distributed throughout East, Southern and Central Africa.
While the Pemba blue duiker may resemble its mainland cousins, the island’s long separation may have created conditions for the animal to become something genetically unique.
“When species end up in a place under similar ecological pressure, morphologically they can stay similar to the original population, even if they’ve been isolated for a million years,” said Michele Menegon, a conservationist and herpetologist based in the mainland Tanzanian city of Arusha.
“An oval with legs and two little horns — there are not many features that can change.”
The diminutive blue duiker, standing just 30 centimeters (12 inches) at the shoulder, belongs to the Bovidae family of mammals, notable for its much larger members.
“Basically it’s the same family as the buffalo, but probably only weighs the same as the tongue of a buffalo,” said Menegon, who was helping to survey wildlife in early December alongside the Oikos Institute, an Italian nonprofit working with the Zanzibar government to manage the Ngezi reserve.
The native forests of Pemba Island, part of the Zanzibar archipelago, have all but disappeared in little under a century, but the 2,900-hectare (7,200-acre) Ngezi Forest Reserve is one of the few remaining patches of intact forest. Local informants have told Ngezi’s acting chief-in-charge, Khamis Ali Khamis, about a number of places where elusive blue duikers may still be found.
One of these is in the southeast corner of the reserve, reached via a bumpy road that marks the boundary between the reserve and farmland where native zebu cattle graze beneath coconut trees. In early December, a group of local forest guards and members of a team from Oikos visited this patch of forest to look for signs of life.
The area the team was surveying was traversed by numerous footpaths; not animal paths, but those made by firewood collectors and trap setters. Unlike the camera traps, however, these traps were set to kill animals, and the likely target, Khamis said, were small mammals like the blue duiker and the eastern tree hyrax (Dendrohyrax validus).
Along one of these paths he found and snapped off a nylon noose that was cunningly attached to the end of a piece of native vine. He estimated it had been set at least a month earlier, and was still strong enough to hold a trapped animal.
Ironically, considering the team’s mission, the traps were actually a good sign. They meant that this patch of forest might still hold blue duikers in it.
“They still exist inside the forest, but there are very few,” Khamis told Mongabay.
Days earlier, when they visited this site, all they found was a tiny jawbone and a piece of skull. But no duikers. Now, at the site of an ancient tree fall, shiny-leaved Dracaena fragrans shrubs provided the sort of thick cover favored by the duikers. Encouraged by the bone fragments they’d found earlier, Menegon and Khamis set up camera traps at this and other spots, attaching them near the base of slender plant stems, and sprinkling bait on the ground that would hopefully prove irresistible: diced coconut mixed with peanut butter.
Once the camera traps were set, and the team was bumping its way back in a vehicle to a temporary field station at the heart of the reserve, Menegon told Mongabay that he and colleagues would work with local authorities to have DNA from the jaw and skull fragment tested. This might help to clarify whether the Pemba blue duiker is indeed a subspecies, or even a species in its own right. If it’s the latter, it could help raise the profile of the animal as a candidate for urgent conservation action.
DNA analysis could also help to clarify how long ago the animals occupied Pemba Island, which lies around 50 kilometers (30 miles) from the coast of Tanzania and is estimated to have separated from the continent 10 million years ago.
“Considering the special characteristics of the island, the time of isolation and the biogeographical context, molecular investigations of any species that may have colonized the island over the past thousands or millions of years would be desirable,” Menegon told Mongabay.
Some scientists don’t consider the Pemba blue duiker to be a subspecies at all, suggesting instead that it’s the same as the blue duikers that live in coastal areas of Tanzania and Kenya. DNA sequencing could settle that debate too.
Mongabay was present when Khamis and Menegon downloaded the pictures from a camera trap they had promptly set up on the day they found the blue duiker remains.
“It could be a Beamys hindei [long-tailed pouched rat] with that white belly,” Menegon said, squinting at a dark shadow flitting across the tiny screen.
His colleague, Oikos project adviser Silvia Ceppi, whipped a laptop out of a rucksack. Seen on the bigger screen, the image of the rat clambering along a vine and, a little later, the bushy tail of an indeterminate species of galago, a small nocturnal primate, were clearly visible.
But still no duikers.
Two days after setting up the camera traps, however, Menegon and fellow herpetologist John Lyakurwa were walking along a trail through a different part of the reserve’s moist evergreen forest when Lyakurwa heard a movement in the undergrowth.
“I turned and I saw something like a small antelope,” he told Mongabay afterward. “I said, ‘Michele, there’s an antelope,’ and Michele moved some meters further and he managed to also see it.”
This is believed to be the first official sighting of the Pemba blue duiker in more than 20 years.
Menegon said the fact that it was spotted in a section of forest some distance away from the site of all the poachers’ traps suggests there may be at least two tiny populations of the animals persisting against all odds.
“I’m very happy,” he said. “Now we have an antelope to celebrate, rather than an antelope to mourn.”
Banner image: A blue duiker (Philantomba monticola) — the Pemba blue duiker is a subspecies of this small antelope that has become genetically unique from its relatives on the African mainland over time. Image by Derek Keats via Wikimedia (CC BY-SA 2.0)
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