The Njesi Plateau expedition; A quantitative assessment of biodiversity on the Serra Jecci massif (Mozambique) – addressing a biogeographical gap in the East African Rift

The southerly reaches of the East African Rift run south from Tanzania through eastern Malawi, largely lying to the west of Lake Malawi. Scattered adjacently to the east, throughout north and north-central Mozambique, are a number of isolated mountains and massifs (e.g. Mts. Namuli and Mabu) with Mt. Gorongoza representing one of the largest massifs to the south. Owing to the historic conflict-fractured nature of Mozambique, these mountains have remained generally off-limits until recent years and as a result also poorly explored scientifically with their biodiversity and habitats largely undescribed. This lack of biogeographical information can be broadly extended to the majority of northern Mozambique, with even basic information on vertebrate species diversity and abundance lacking. Latterly, however, a program of research and exploration efforts has highlighted how unique these forested massifs are, with particular focus placed on documenting the montane forests of Mts. Mabu and Namuli.

These expeditions accentuated not only the biological uniqueness of the southerly mountains of the East African Rift, but also the vast knowledge gaps in data on all taxa. Several new species were described as a result, such as 5 new Chameleons (Branch & Tolley 2010; Branch et al. 2014), the forest viper Atheris mabuensis (Branch & Bayliss 2009), the bat Rhinolophus mabuensis (Taylor et al. 2012) and 7 new Butterfly taxa (Congdon et al. 2010). Furthermore, species assemblages across several taxa represented that of a distinctly different composition to the comparatively well-studied mountains of southern Tanzania, but with ancient linkages, suggesting long periods of isolation. Subsequently, it has been suggested that these high-altitude massifs and their associated habitats may comprise a unique montane eco-region (Bayliss et al. 2014).
In light of these recent findings, biological assessments of similar unstudied massifs further north in Mozambique now exhibit a key missing link in the interpretation of east African biogeography and for the potential appraisal of this unique eco-region and subsequent protected areas.

  • One of highest inselbergs in northern Mozambique is that of the Njesi Plateau (12°49’19.8″S, 35°11’39.9″E) in Niassa province, with heights reaching in excess of 1800m. The Njesi Plateau is situated some 330km and 400km north of Mounts Namuli and Mabu respectively, comprising of high plateaus and a series of mountain peaks topped with seemingly pristine evergreen forest patches, interspersed with grasslands and bare granite protrusions. On the lower slopes, the plateau is surrounded by pristine miombo woodland with a seemingly large intergrade zone of mixed woodland-types as altitude increases (C. Spotiswoode in litt.). To date, the Njesi plateau remains virtually unexplored scientifically, particularly on the northernmost mountains of Chitagal and Chilungo (Spotiswoode et al. 2008) and, like much of Niassa province, little to no information on its biodiversity is available. Current information is based upon a one day avifaunal survey in 2001 (Ryan & Spotiswoode 2001), a 6 day survey of the herpetofauna in 2011 (Portik et al. 2013) and a 3-day exploratory visit sampling the Lepidoptera in 2009 (Congdon et al. 2010). The latter two visits were to the more accessible main plateau. Historically, a brief collecting effort of birds was also undertaken in 1945 (Benson 1945, 1946), although no specific location is available.
  • Owing to difficult access, these efforts almost exclusively sampled the southerly extreme of the plateau with the northern peaks of mount Chitagal and Chilungo remaining unsurveyed despite harbouring perhaps the most extensive areas of montane forest habitat on the plateau. Furthermore, previous data on the taxa sampled was largely opportunistic in nature with the habitats and extent of forest cover present not formally assessed. Thus, the terrain is still largely known from google earth satellite imagery. Preliminary observations of the biodiversity of the massif were highly promising, however, including the re-discovery of the highly disjunct sousae race of Long-billed tailorbird, a Critically Endangered East African endemic known only from northern Tanzania and the discovery of a Butterfly species (Charaxis nov.) new to science and currently awaiting formal description (Ryan & Spotiswoode 2003; J.Bayliss in litt.). No data is available on any other flora or fauna from the plateau, although Ryan & Spotiswoode (2003) mention local people suggest they harbour populations of large vertebrates such as Elephant, Leopard, Zebra and Sable antelope. In light of a burgeoning local population and ongoing deforestation its impact will likely be felt here soon. Considering the large number of endemic species associated with similar outcrops in other areas of Mozambique and especially the positioning of the Njesi Plateau, an expedition assessing its biodiversity and to collect quantitative information on the already known highly endangered taxa of the massif is critical.

We mounted the first multiple taxa biodiversity exploration of the northernmost mountains of the Njesi plateau. In an express biodiversity survey with 8 scientists, partly national, partly international, we surveyed montane forest on Mt. Chitagal, Mt. Sanga and the Njesi plateau. We climbed the peaks on foot and camped in their associated forest patches to perform standardized biodiversity surveys for selected taxa. Taxa included were birds (mistnetting and point counts focusing particularly on assessing the populations of Long-billed Tailorbird), large mammals (camera trapping), small mammals (Sherman traps), amphibians and reptiles (VES), ground beetles and spiders (pitfalls), butterflies and Odonata (butterfly net) and selected moths (hawkmoths and emperor moths) (light trapping). The main goal is to assess the biodiversity in the montane forest patches, describe new species encountered and quantitatively document species assemblages through well-established rapid assessment protocols. It provides some of the first quantitative baseline assessments of a variety of taxa for northern Mozambique. With the collected data we aim to formally assess, document and present its conservation value and contribute to an ongoing conservation effort for the larger region by the Rift Valley Corporation. We hope that our data will form key contributions to the assessment of southern African montane biogeography and sparse biological coverage of Mozambiques montane environments. 

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James Egremont-Lee (Rift Valley Corporation, Niassa, Mozambique)
Rudy Jocque, PhD (Royal Museum for Central Africa, African spiders)
Rosser Garrison, PhD (California Pest Management, dragonflies)
Simon Loader, PhD (University of Basel, Switzerland, African frogs)


Sam Jones (UK)
Merlijn Jocque (Belgium)