World’s smallest primate is fading into extinction, scientists fear

The world’s tiniest primate, the Madame Berthe’s mouse lemur (Microcebus berthae), a creature small enough to curl inside a human fist, could soon disappear as the human imprint on its forest habitat grows.

Since 2018, surveyors deployed at the lemur’s preferred habitat in Madagascar’s western dry forests have failed to spot the animal, stoking fears that the lemur, described just 30 years ago, is already on the verge of extinction.

Lemurs are endemic to Madagascar, which is home to an astounding variety of them: more than 100 are known to science. But most of these species occupy niche habitats, amplifying the danger from habitat loss. Nearly all 107 lemur species on the IUCN Red List are on the path toward extinction, with 103 falling in the critically endangered or endangered categories.

Signaling a deepening environmental crisis in a renowned biodiversity hotspot, this September, another team of researchers warned that the Milne-Edwards’s sifaka (Propithecus edwardsi), a species native to the tropical rainforests of eastern Madagascar, could vanish in 25 years.

“The risk of extinction accelerates dramatically when we take into account deforestation and climate extremes,” said Eric Isai Ameca y Juárez, a specialist in biodiversity loss and climate change at Beijing Normal University. The team, including researchers from Centre ValBio, Ranomafana National Park in Madagascar, published their findings in the journal Biological Conservation.

These rain-fed forests that run down Madagascar’s eastern flank are vulnerable to cyclones that regularly strike the country’s eastern shoreline and bring heavy rainfall inland, leading to habitat degradation. Storms damage vegetation and degrade habitats. But it is droughts that have the most insidious effects. Abnormally dry conditions can translate into poor fecundity for Milne-Edwards’s sifakas and can cause infant lemur deaths.

However, Juárez said, a shrinking habitat is the biggest danger for the sifaka.

Madagascar’s protected area estate grew more than four times in the past two decades, covering about 8% of its terrestrial area. Many of these conserved areas protect the remaining rainforests and dry forests, both of which are home to an eye-watering number of living organisms. However, protected areas have met with limited success on the island.

What works in favor of P. edwardsi is that a chunk of its range lies within Ranomafana National Park, the oldest national park in Madagascar and one of the better-preserved parks in the country. Deforestation rates within its boundaries are significantly lower than outside, where villagers clear forests to grow food crops like rice or cut down trees to make charcoal.

The Menabe Antimena Protected Area, known by its French acronym APMA, is the Madame Berthe’s mouse lemur’s only known habitat and is witnessing massive forest loss. About a third of the tree cover of the park, spread over 210,300 hectares (519,700 acres), has been scrubbed out since 2015, when it became a protected area.

The dry deciduous forests of Kirindy and Ambadira within APMA are believed to host Madame Berthe’s mouse lemur populations.  For decades, the Kirindy forest has been under severe deforestation pressure as plantations of food crops like maize and cash crops like peanuts eat into centuries-old woodland.

While poverty fuels much of this destruction, many experts, including Matthias Markolf, a conservation biologist at the University of Göttingen, say poor enforcement of environmental regulations also plays a role. Markolf and his colleagues at the German Primate Center in Göttingen published a study in the journal Conservation Science and Practice about the M. berthae surveys.

The forests of Menabe Antimena are subject to greater pressure because many Malagasy citizens migrating from the country’s parched south in search of livelihoods settle in the region. Prolonged drought conditions have left communities in dire need of food, and for many migrating to bigger settlements north is the only way out of crushing poverty.

“Without a strict strategy and strong economic alternatives for all the communities who are migrating every year, the issues will remain,” said Tiana Andriamanana, executive director of Fanamby, one of the nonprofits managing the Menabe Antimena Protected Area. “We cannot respond to all the needs.”

The years-long pandemic disruptions have only made matters worse, impacting both Menabe Antimena and Ranomafana, where a steep fall in tourism income has disrupted local economies. This revenue source also funds government agencies involved in conservation work, which already face perennial finance and human resource shortages.

There is no state-run program to monitor lemur populations, even within protected areas. The Malagasy government shares responsibility for managing the protected area network with a semiautonomous agency, local community associations, and a bevy of international and local NGOs.

The plight of the Madame Berthe’s mouse lemur came to light because scientists went out in search of the iconic lemur in a famous park. For many other species, there is no such surveillance. In the past few years alone, several new lemur species have been added to Madagascar’s tally, including a mouse lemur, Microcebus jonahi, in 2020. We know very little about them, their population distribution, their ecology, or how they are dealing with human impacts, Markolf said.

A sliver of hope does exist for the Madame Berthe’s lemurs. Surveys conducted by the German Primate Center this year suggest some individuals are present in other pockets of the lemur’s range. “It is more than urgent to protect the remaining potential habitat,” Markolf said.

Banner image: The Madame Berthe’s mouse lemur is small enough to curl inside a human fist. Image by Matthias Markolf.

Citations:

Kappeler, P. M., Markolf, M., Rasoloarison, R. M., Fichtel, C., & Durbin, J. (2022). Complex social and political factors threaten the world’s smallest primate with extinction. Conservation Science and Practice, 4(9). doi:10.1111/csp2.12776

Zhang, L., Ameca, E. I., Otero-Jimenez, B., Montaño, S. K., Shea, A., Kelly, T., … Wright, P. C. (2022). Human-induced deforestation increases extinction risk faster than climate pressures: Evidence from long-term monitoring of the globally endangered Milne-Edward’s sifaka. Biological Conservation, 274, 109716. doi:10.1016/j.biocon.2022.109716