A recent survey of tarsier numbers in the Philippines’ Mount Matutum Protected Landscape suggests worrying declines for the cute critters, with light and noise pollution believed to be among the key threats.

By Graeme Green

Published: Wednesday, 11 September 2024 at 08:33 AM


A survey of tarsier numbers in the Philippines’ Mount Matutum Protected Landscape has given conservationists cause for concern. 

The Philippine tarsier is one of the world’s smallest primates and belongs to the Tarsiidae family, with species found in Southeast Asia, including the Philippines, Borneo and Sulawesi. With large bulging eyes, a tiny body and long fingers, they are often compared to science fiction characters ET and Yoda.

But their cuteness has counted against them – they have been poached for the pet trade and made to pose for photos with paying tourists. Habitat loss, along with sound and light pollution are another key threats. Tarsiers are currently listed on the IUCN’s Red List of Threatened Species as Near Threatened.

Tarsiers are nocturnal primates about the size of a tennis ball/Getty

The Tarsier Sanctuary in the Mount Matutum Protected Landscape in Tupi, South Cotabato, in the Philippines was created in 2013 by the Department of Environment and Natural Resources (DENR), based upon an initial 2012/2013 survey that found a healthy population of tarsiers. 

Wildlife NGO Endangered Species International (ESI) conducted a 54-day tarsier population inventory in the Tarsier Sanctuary between September 2023 and June 2024, covering 815 hectares within the Mount Matutum Protected Landscape (509 hectares within the tarsier Sanctuary and 209 hectares outside the sanctuary).

Compared with the original survey in 2012/2013, the recent study suggests tarsier numbers have reduced by around 50%, with a concerning lack of infants seen.

Tarsier
Tarsiers have the largest eyes relative to body size of any mammal/Getty

The original 2012/2013 surveys were conducted solely inside the Tarsier Sanctuary – the latest survey covered a larger area, as conservationists encountered less tarsiers inside the sanctuary and wanted to see if they could find more beyond the sanctuary’s borders.

“In the 2012/2013 survey, there were 33 captures over 54 days,” says Pierre Fidenci, Founder and President of ESI.

“In 2023-24, we captured only five. Based on all sightings, we estimate the population of the Philippine tarsier to be below 15 individuals in the Tarsier Sanctuary and up to 21 tarsier individuals for the total 815 hectares.

“The population estimate was at least 40 tarsiers for the Tarsier Sanctuary in 2012/2013. We didn’t find any infant tarsiers during the 2023/24 surveys, whereas we encountered infants on several occasions in the first surveys of 2012/2013.”

“The situation is worrying, as we know few strongholds for the Philippine tarsier in the Philippines,” he adds. “Their decline is not good news as their current threats, especially habitat loss, noise and light pollution, are increasing in the Philippines, including within known tarsier areas.”

Fidenci believes the decrease in tarsier numbers could be “partly attributed to changes that have occurred in the village communities surrounding the sanctuary, particularly in Purok Bagong Silang.

“When ESI conducted its initial survey in 2012/20133, Purok Bagong Silang, a B’laan (Indigenous people) village inside the sanctuary, had no access to electricity. It was only connected to the power grid in December 2016. This development enabled villagers to use electric lamps during evenings and operate loud appliances, like radios and televisions, during the day.

“Noise pollution in the daytime, when tarsiers are usually asleep, may have resulted in sleep disturbances that negatively affected the tarsiers’ wellbeing and behaviour.”

“Tarsiers are known to be very sensitive to light. Noise pollution in the daytime, when tarsiers are usually asleep, may have resulted in sleep disturbances that negatively affected the tarsiers’ wellbeing and behaviour. We also observed that habitat within the tarsier sanctuary has been impacted due to encroachments and farming.”

Tarsier
Tarsiers, which are sensitive to light and noise, usually sleep in the daytime/Getty

Urgent action is needed, Fidenci suggests, in the Mount Matutum Protected Landscape but also in other tarsier areas across the Philippines.

“The population of the Philippine tarsier in the Tarsier Sanctuary has declined over a decade, which requires the implementation of immediate conservation measures to ensure a recovery and survival of the threatened tarsier,” he says.

“Measures should include habitat restoration (such as tree planting), the removal and stopping of new illegal encroachments within the protected area, noise reduction, and fostering organic ecological agriculture in the area. Human population increases, including noise pollution within the Tarsier Sanctuary, is highly detrimental to the survival of the species.”

Philippine tarsier climbing a tree
A Philippine tarsier grips on…/Getty

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