The Njesi plateau expedition – a biological exploration into Mozambique’s ‘lost’ mountains

We’ve all had those moments; cold leaden skies outside leading to wistful searches for distant lands through the internet – the apparently endless portal that holds all the answers. But does it? Ten years ago, a scientist examining Google Earth satellite imagery of northern Mozambique was looking for the name of a mountain, but he couldn’t find it. Thereafter, he embarked on a remarkable story of scientific exploration in modern times, a story that opened the eyes of the world to the biological wonders of the mountains of Mozambique.

The mountains of East Africa, running southward through Kenya, Tanzania and to the west of Lake Malawi, are well known for their exceptional biological diversity. Because of their altitude, unique habitats, and separation from the lowlands of the region, these mountains harbour large quantities of highly range-restricted and endemic species. Much lesser known, but lying directly adjacent to these mountains, to the east of Lake Malawi, are the mountains of northern Mozambique. Scattered across the vast landmass north of the Zambezi River, are isolated clusters of mountains lying adjacent to, but disjunct from, the main highlands to the west. The cooler and wetter conditions on these isolated mountains have allowed lush tropical forest to flourish, forming ‘sky islands’ of unique habitat distinct to the surrounding lowlands, typified by Miombo woodland habitats.

Maps showing the relative positions of the southeast African highlands, the topography of the highlands in Tanzania, Mozambique and Malawi and the locations of specific north and northcentral Mozambiques mountains, including Mount Mabu.
Figure from Jones et al 20171, used with permission.

Until recently, however, the biodiversity of Mozambique’s mountains remained largely undocumented. A cocktail of geographic remoteness, continual conflict in the post-independence civil war, and limited historic study during its Portuguese colonial occupation, has majorly inhibited the exploration and biological understanding of these ‘lost’ mountains. Over the last decade, exploratory research efforts have shone new light on Mozambique’s mountains, largely catalysed by the discovery of the mountain with no name. The afore-mentioned unnamed mountain, discovered by Dr Julian Bayliss through the lens of Google Earth satellite imagery, we now know to be the largest mid-altitude rainforest in southern Africa; Mount Mabu. The discovery of Mount Mabu led to a series of other spectacular findings, including large numbers of species new to science (e.g. multiple new species of Chameleons2 and a new forest viper3) and significant new populations of threatened and range-restricted species (e.g. birds4). This series of discoveries occurred both on Mount Mabu itself and in exploring similar known, but poorly-studied mountains in Mozambique. Taken together, the distinct assemblages of species discovered on Mozambique’s mountains posed two timely questions:

  • Firstly, what other discoveries are there to be uncovered in Mozambique’s mountains, with greater survey effort?
  • Secondly, owing to their apparent distinctiveness, do these mountains warrant recognition as a unique ‘ecoregion’ in their own right?

The remote and intact montane forest patches of northern Mozambique attracted the Njesi Expedition team to conduct exploratory research.
Image by Mac Stone, used with permission.

As zealots of remote, poorly-studied places, these were questions pondered by myself and my friend and colleague Merlijn Jocque while sitting around a campfire late at night in our regular field site in Honduras, in the summer of 2015. Fast-forward over two years – after hundreds of hours of research, organising collaborations, preparing permits, and raising funds – and we find ourselves sitting around a campfire again. This time however, with Gallagos and African Wood Owls calling in the inky blackness surrounding us, we are sitting in a patch of forest at the foot of Mount Chitagal in Mozambique’s remote north-western Niassa province, a mountain that no biologists have previously visited.

Tim Van Berkel studies a strangler fig in the dense primary forest on the summit of Mt Chitagal.
Image by Mac Stone, used with permission.

Our expedition to the Njesi plateau

The highlands of Niassa province form some of the most significant highlands in northern Mozambique and one of the ‘stepping stones’ to mountains further north in Tanzania. Our expedition sought to document the biodiversity of the Njesi Plateau through a short, sharp biodiversity assessment expedition, bringing a variety of international experts in different disciplines to work on the ground all at once. Our team was comprised of eight local and international scientists spanning a range of expertise from birds to botany; a photographer, filmmaker, two local guides, a forest guard and a camp manager.

The highlands of the Njesi plateau region are made up of three key mountains/plateaus – those of Mount Chitagal, Sanga and the Njesi Plateau. Only rough topographical maps were available so most of our routes were plotted by a combination of satellite imagery and the help of local guides to find suitable campsites and water sources. Access is only possible on foot, taking up to 2 days to get to certain highland forests of interest. In practical terms this meant our team, with the help of an additional 25 porters during transit, carrying over 500kg of equipment for each mountain, often breaking camp far before dawn in order to escape the merciless daytime heat.

On each mountain, we set up camp in forest patches at altitudes typically above 1500masl. Sampling took place in the forest patches around each camp and nearby. Because of the diversity of our research team, work was being undertaken virtually around the clock, from dawn bird surveys to late night light-trapping and surveys for amphibians along streambeds – all fuelled by the simple childhood desire to explore and discover. And the discoveries came thick and fast. We found several large range extensions and new national records for multiple species of birds, confusing species of amphibians that may turn out to be new to science, once genetic work has been undertaken, and many insect species that are almost certainly new to science. At least on two of the peaks, human pressures were apparently low, meaning that many of the species we were documenting are not under any immediate threat.

Long-billed Tailorbird were found on all three mountains, and the team were able to collect data on their population, genetics and behaviour.
Photograph by Sam Jones.

Of particular interest to myself and Gabriel Jamie (the other ornithologist on the expedition), was the presence of the little-known, but highly endangered Long-billed Tailorbird (Artisornis moreaui) a species known only from one tiny population over 900km to the north in the Amani mountains of Tanzania. Virtually nothing is known about this species in Mozambique, and before our visit this Mozambican population had been seen by just three ornithologists.

We were excited to find large numbers of Long-billed Tailorbirds on all three mountains, indicating that its apparent rarity is largely an artefact of its remoteness and lack of historic study. Because of the number of Tailorbirds we encountered we were also able to collect valuable data on their population, genetics and behaviour, which once fully analysed will significantly increase our understanding of this rare and peculiar species.

Despite two years of preparation, the expedition was over in a flash, but as we finalise our full report we are also fully aware that discoveries will continue to be unearthed as species are sorted through in specimen draws at different museums and as our results gradually make their way out into the broader scientific literature.

It can be easy to forget sometimes how little we know about many regions of the world. The mountains of northern Mozambique are a shining example that there are still new worlds to discover, ‘lost’ species that we know nothing about and biological frontiers waiting to be explored. It’s just down to us, to look.

Rocky outcrops of Sanga Mountain, Mozambique.
Image by Mac Stone, used with permission.

References

1. Jones S.E.I., Clause J.K., Geeraert L., Jamie G.A., Sumbane E., van Berkel, T. and Jocque M. (2017) The Njesi Plateau expedition: a biological assessment of Mt Chitagal, Mt Sanga and the Njesi Plateau in Niassa Province, Mozambique. BES Report 6.3 (25 October 2017). Biodiversity Inventory for Conservation. Glabbeek, Belgium, 80 pp.
2. William r. Branch, Julian Bayliss, Krystal Tolley (2014) Pygmy chameleons of the Rhampholeon platyceps compex (Squamata: Chamaeleonidae): Description of four new species from isolated ‘sky islands’ of northern Mozambique. Zootaxa
3. William r. Branch, Julian Bayliss (2009) A new species of Atheris (Serpentes: Viperidae) from northern Mozambique. Zootaxa
4. Claire N Spottiswoode, Hassam I Patel, Eric Herrmann, Jonathan Timberlake & Julian Bayliss (2009) Threatened bird species on two little-known mountains (Chiperone and Mabu) in northern Mozambique. Journal of African Ornithology

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