After 70 years, juvenile Mindanao treeshrews spotted anew on Dinagat Islands

The juvenile Mindanao treeshrews found by biologists in July 2022 on Dinagat Islands. MindaNews photo courtesy of TRISTAN LUAP SENARILLOS

KORONADAL CITY (MindaNews / 06 March) – After at least 70 years, two Filipino biologists have rediscovered by accident a pair of newborn Mindanao treeshrews (Tupaia everetti or T. everetti), a mammal resembling the traits of a chipmunk, on Dinagat Islands.

Tristan Luap Senarillos and Jayson Ibañez, both conservationists of the Philippine Eagle Foundation in Davao City, said they discovered the nest site within the Mounts Kambinliw-Redondo key biodiversity area in July last year.

“This nest discovery is a valuable contribution to the minimal existing literature about this poorly studied species, which may be increasingly threatened by anthropogenic impacts,” the duo said in a research paper.

It was titled “Notes on the Nest Architecture and Nest Site Characteristics of Mindanao Treeshrew (Tupaia everetti Thomas, 1892) from Dinagat Islands, Philippines,” which was published on March 1 at the Philippine Journal of Science.

Anthropogenic impact refers to changes to biophysical environments and to ecosystems, biodiversity and natural resources caused directly or indirectly by humans.

The biologists found the Mindanao treeshrew nest on the ground, built inside a cavity of a dead pandan tree surrounded by natural vegetation.

But none of the attending parents were seen during the encounter.

The team was carrying out a rapid faunal assessment at a community watershed area in Barangay General Aguinaldo in Libjo town, with the aim to document avifauna (birds), herpetofauna (amphibians and reptiles) and non-volant (incapable of flying) mammals in post-typhoon Odette, when they accidentally discovered the nest of the juvenile Mindanao treeshrews.

Typhoon Odette (international name: Rai) devastated Dinagat Islands in December 2021.

“(They are) secretive. They adapted to or specialized in climbing,” Senarillos, corresponding author, told MindaNews on Sunday. “So far, what we know is that they are diurnal (daytime) animals, are omnivores and found in areas associated with forests.”

“Mahirap sila makita sa field unless mag trap for study purposes (They are difficult to find in the field unless you trap them for study purposes),” he added.

The Mindanao treeshrew is one of the only two endemic treeshrews in the Philippines. The other is the Palawan treeshrew (Tupaia palawanensis).

According to the authors, the Mindanao treeshrew is an enigmatic non-volant mammal found only in the mountainous areas of mainland Mindanao and smaller nearby islands, including Dinagat and Siargao. 

The IUCN Red List of Threatened Species classified Tupaia everetti as a species of “least concern.”

It is reported to inhabit dense understory vegetation in close proximity to streams in lowland evergreen forests (below 500 meters above sea leave or masl) up to mossy forests (2,250 masl) and is occasionally encountered in varying densities in disturbed forest habitats, Senarillos and Ibañez wrote.

The nest of Mindanao treeshrews found by biologists in July 2022 on Dinagat Islands. MindaNews photo courtesy of TRISTAN LUAP SENARILLOS

In the wild, the Mindanao treeshrew utilizes hollows on the ground as nest and hiding places, they added, citing the “Notes on the Philippine Treeshrew, Urugale everetti Thomas. Journal of Mammalogy” (Wharton, 1950).

With regards to breeding, females in captivity are reported to produce two offspring after a gestation period of 54 to 56 days, the duo said.

Senarillos said there is little information about treeshrew species in the Philippines.

But based on studies with their relatives in peninsular Borneo, the Tupaia species are believed to contribute as seed dispersers, helping to regenerate fruiting trees in the forests they inhabit, he noted.

Both males

Both the discovered juvenile Mindanao treeshrews found in the nest were males.

“They slept in a curled, tight ball position, with the top of the head located very close to the belly, or in a ventral position with the tail resting on top of the belly,” the researchers said.

“Whenever the nest was disturbed, the juveniles became active and made an explosive snort and quick scratching motions, probably a form of territorial defense to deter predators and other nest intruders,” they added.

At the time of the observation, the juvenile T. everettis were already covered with dark brown fur and had rufous underparts. Their eyes were still closed though and when they opened their mouths, no dental development was observed. 

The researchers avoided touching the juveniles to prevent stress and human scent contamination, which could possibly lead to nest abandonment by the attending adults.

Mining threats

In Dinagat islands, the authors said that mining is the leading threat to biodiversity loss since the entire island province was declared a mineral reserve under Presidential Proclamation No. 391 of 1939, which legalized the quarrying of large forested areas on the island. 

There are 19 mining companies currently operating on Dinagat Islands for silver, nickel, copper, chromite, limestone and silica deposits.

Fortunately, the forest of Barangay General Aguinaldo where the juvenile Mindanao treeshrews were discovered is well-protected since it is declared a community watershed, the researchers noted. 

“The Mindanao treeshrew population’s long-term reproduction (on Dinagat Islands) benefited greatly from this level of nesting site protection,” they said.

Outside of Dinagat island, there is a stable population of T. everetti in several mountain ranges in Mindanao. 

“However, its widespread distribution does not warrant its conservation and protection due to deforestation and hunting pressures,” the authors said.

The authors highly recommended conducting more nest research and breeding ecology studies on Dinagat islands and other areas where T. everetti is found to determine if the nesting pattern is similar to what was discovered in their study. (Bong S. Sarmiento / MindaNews)