- Six new species of pygmy chameleon have been described from Tanzania’s Eastern Arc Mountains.
- The mountain forests are subject to intense human pressure, threatening the diverse plant and animal species that live in them.
- A recent study using satellite imagery discovered that in one district alone, 27% of its montane forests were lost to small-scale farmers and herders between 2011 and 2017.
- The Tanzanian government is currently working to increase agricultural production in a region that overlaps with the Eastern Arc Mountains, raising fears this will be at a cost to biodiversity.
Michele Menegon and a team of local and international scientists have just described six new species of thumb-sized chameleon in Tanzania’s Eastern Arc Mountains. The forest-capped mountains form an inland archipelago, stretching 900 kilometers (560 miles) from the northern tip of Lake Tanganyika to the Taita Hills in southeastern Kenya. Much like the 13 islands of that other famous archipelago, the Galapagos, the Eastern Arc’s 13 isolated mountain blocks harbor startling biodiversity.
The latest discovery brings to 26 the total number of Rhampholeon, or pygmy chameleons, described to date. More than half of them live in the Eastern Arc Mountains, whose mountain blocks resemble biological islands that have become the sites of species radiation for the tiny reptiles, just as the Galapagos Islands did for Charles Darwin’s finches. But these forests are threatened by farmers and herders who clear them to grow crops and raise livestock. Most of the six newly described chameleons are already at risk of extinction due to habitat loss, according to researchers.
Menegon, an ecologist, conservationist and researcher, began working in the Eastern Arc Mountains 30 years ago. He would emerge after a day spent in the forest with more unknown species on his list than known ones.
Most of the pygmy chameleons are endemic, or unique, to individual mountain blocks.
Sometimes they are confined to a small patch on a single mountain, Menegon told Mongabay. “If you go to one side of the mountain — at a certain elevation — you have a species. You move to another side of the mountain, at another elevation, you have another species.”
Shortly after his paper was published, Menegon discovered what is likely to be yet another new species. It was during a visit he made to the forested flanks of one of the mountain blocks — the Nguru Mountains — in Tanzania’s Morogoro Region. This chameleon was small and spiny with long horns above its eyes.
“When I saw it, I thought, ‘OK, this is different. We start again,’” he said.
The biodiversity extends beyond chameleons: At least 800 plants and at least 96 vertebrates — including birds, reptiles, amphibians and mammals — live there and nowhere else.
“In 3,500 square kilometers [1,350 square miles] of closed-canopy forest in the Eastern Arc Mountains, there is roughly the same number of amphibian species as the entire Democratic Republic of Congo [at 2.3 million km2 (888,000 mi2)],” Menegon explained.
“It is unbelievable.”
The deforestation threatening this treasure trove of biological diversity stems from the demand for agricultural land. Tanzania’s human population, which grew to more than 63 million in 2021 from around 35 million in 2002, needs land on which to grow crops like bananas, cassava and maize.
In the Eastern Arc Mountains, cardamom is also in demand. For that, farmers do need some shade: Large trees are left standing while the understory is cleared. But that is the very place where the chameleons live.
“We have lost some of [the chameleons] already, in the forest that’s no longer there,” said Menegon, who is also co-director of the PAMS Foundation, a conservation NGO.
The Tanzanian government has over the past 10-15 years tried to stem biodiversity losses by upgrading the status of a number of high-altitude forest patches in the Eastern Arc Mountains from forest reserve to nature reserve, he said. On paper, at least, that should give them more protection. In reality, there are insufficient resources to patrol them and enforce the law.
“Farmers are getting into the forest and clearing more and more,” said Menegon. “There is no clear idea on how to control access.”
A separate study using satellite imagery discovered that in the Mvomero district alone, more than 20,000 hectares (50,000 acres), or 27%, of its montane forests were lost or degraded between 2001 and 2017. The district includes the Nguru mountain block that is home to two of the newly described pygmy chameleons and the peculiar undescribed horned species that Menegon stumbled upon a few weeks ago.
The lead author of the forest loss study, Eliakim Hamunyela from the University of Namibia, told Mongabay that a lack of funding has meant he and his team have not been able to track deforestation trends beyond 2017. He said despite the existence of forest reserves, the encroachment by farmers into them represented “a loophole in the current mechanisms for protecting forests in this area.”
His study found that at least 12% of all forest disturbances that occurred in Mvomero district, including deforestation, happened within areas designated as forest reserves. Immigration to the area by pastoralists may have contributed to the disturbances, he said.
The Nguru mountain block is composed of two main areas. According to the World Database on Protected Areas, the northern portion has been part of the Kanga Forest Reserve since 1954 while much of the larger southern portion was gazetted as the Mkingu Nature Forest Reserve in 2019. Satellite data from forest monitoring platform Global Forest Watch show deforestation has intensified in both reserves since the turn of the century, particularly in Mkingu where forest loss jumped nearly sevenfold between 2017 and 2020. Both Mkingu and Kanga experienced comparative lulls in deforestation in 2021, but preliminary data for 2022 and 2023 suggest forest loss has rebounded.
Cattle herders, including the Barabaig, Maasai, Mbulu and Sukuma, have been migrating to Mvomero from drier regions in search of water and pasture. Ground-truthing surveys by Hamunyela’s team found that cattle browsed saplings and seedlings, meaning that land left fallow by the district’s farmers could not easily regenerate trees.
The team also noted that agriculture-driven forest loss within Mvomero may relate, in part at least, to the Southern Agricultural Growth Corridor of Tanzania, or SAGCOT — a joint initiative launched more than a decade ago by investors and the Tanzanian government to promote food production in the region by linking small-scale farmers to markets.
“Market-driven agricultural development is likely to trigger an expansion of cropland at the expense of forests to meet the increased demand for the agricultural products promoted,” the study warned.
Geoffrey Kirenga, the chief executive of SAGCOT Center Limited, told Mongabay it would be unfair to suggest the initiative was promoting biodiversity loss. He said his organization championed the opposite by, among other things, holding annual meetings with partners throughout the region on preventing bushfires and the expansion of slash-and-burn agriculture, especially in mountainous areas. He said SAGCOT believed in taking care of the environment for sustainable transformation of food systems.
“We care for our environment, soil, water and biodiversity on it,” he said in an email. “Indicator organisms such as butterflies, birds, chameleons and even mammals are critical tools to show the environment’s health and should be protected by all means.”
What is certain is that in a country like Tanzania, with its showpiece natural wonders like the Serengeti National Park, Ngorongoro Crater and Mount Kilimanjaro, the species-rich forests of the Eastern Arc Mountains and the threats facing them are all too easily overlooked.
“A place like this in another country would be a super-bright highlight,” said Menegon, the chameleon expert. “I think the Eastern Arc Mountains as a whole need to be raised in terms of profile.”
To try to do that, he and his co-authors named some of the new chameleon species after prominent individuals.
Princeeai’s pygmy chameleon (Rhampholeon princeeai), for instance, was named after U.S. rapper and poet Prince Ea. He’s been honored for his work highlighting threats to the environment around the world, including deforestation. Wayne’s pygmy chameleon (Rhampholeon waynelotteri) was named in honor of Wayne Lotter, a South African conservationist and co-founder of the PAMS Foundation who worked to combat poaching in Tanzania before his assassination in Dar es Salaam in 2017.
Tim Davenport — the East African regional focal point for the Key Biodiversity Areas Program —agreed that much more needs to be done to market the Eastern Arc Mountains for tourism and conservation.
Recently retired as director of the Wildlife Conservation Society’s Tanzania program, one of the projects Davenport is promoting is primate tourism in the Eastern Arc Mountains and the Southern Highlands. It was in the Southern Highlands where he and the WCS team got Mount Rungwe — an extinct volcano whose evergreen forests were threatened by charcoal-burning and logging — upgraded to nature reserve status.
Thirteen years of community-based conservation work around the mountain and the Livingstone Forest in the Kitulo National Park saw numbers of one of the region’s iconic and critically endangered monkey species, the kipunji (Rungwecebus kipunji), increase by 65%.
“You need the resources and the right interested parties to support some of these forests and isolated mountains — dedicated projects that focus on greater protection, greater law enforcement, greater support to communities and greater science,” he said.
Just as the work with the kipunji helped to guide and monitor habitat restoration around Mount Rungwe, so could pygmy chameleons and other charismatic species living in the Eastern Arc Mountains.
“The chameleons will help [as flagship species] but they won’t make it on their own,” noted Menegon, adding that the PAMS Foundation has now started a project working with 180 farmers to replant 300,000 native tree seedlings on the western flanks of the Nguru mountains.
“It’s a fantastic opportunity to restore and bring back part of the forest cover that got lost in the last decades and centuries,” he said. “I see this as an element of hope.”
Banner image: Most of the pygmy chameleons are endemic, or unique, to individual mountain blocks. Image courtesy of Michele Menegon.
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Citations:
Menegon, M., Lyakurwa, J. V., Loader, S. P., & Tolley, K. A. (2022). Cryptic diversity in pygmy chameleons (Chamaeleonidae: Rhampholeon) of the eastern arc mountains of Tanzania, with description of six new species. Acta Herpetologica, 17(2), 85-113. doi:10.36253/a_h-12978
Hamunyela, E., Brandt, P., Shirima, D., Do, H. T., Herold, M., & Roman-Cuesta, R. M. (2020). Space-time detection of deforestation, forest degradation and regeneration in montane forests of eastern Tanzania. International Journal of Applied Earth Observation and Geoinformation, 88, 102063. doi:10.1016/j.jag.2020.102063
Burgess, N., Butynski, T., Cordeiro, N., Doggart, N., Fjeldså, J., Howell, K., … Stuart, S. (2007). The biological importance of the eastern arc mountains of Tanzania and Kenya. Biological Conservation, 134(2), 209-231. doi:10.1016/j.biocon.2006.08.015
Lyimo, E. (2014). An analysis of the stakeholders and drivers of deforestation and forest degradation in the South Nguru landscape. TFCG Technical Paper, 45, 1-59.
Davenport, T. R., Machaga, S. J., Mpunga, N. E., Kimiti, S. P., Mwalwengele, W., Mwaipungu, O., & Makumbule, P. M. (2022). A reassessment of the population size, demography, and status of Tanzania’s endemic Kipunji Rungwecebus kipunji 13 years on: Demonstrating conservation success. International Journal of Primatology, 43(2), 317-338. doi:10.1007/s10764-022-00281-3
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