What we know so far about Finlayson’s squirrels

The Department of Environment and Natural Resources (DENR) issued a public advisory on April 16 about increased sightings of non-native Finlayson’s squirrels around various campuses and city spaces in Metro Manila. 

The Finlayson’s squirrel, or Callosciurus finlaysonii, is a rodent species native to various parts of Southeast Asia, particularly in Cambodia, Laos, Myanmar, Thailand, and Vietnam. These squirrels are terrestrial and highly arboreal, spending most of their lives in trees and are rarely seen on the ground. Their physical appearance may also vary, with coat colors ranging from white to red to black.

They have recently been spotted in various cities throughout the metro, particularly in Quezon City, Makati, Taguig, and Muntinlupa. There have also been reported sightings in nearby provinces, such as Cavite, Batangas, Rizal, and Nueva Ecija, according to the DENR Biodiversity Management Bureau (DENR-BMB), as reported by GMA News. 

A risk to biodiversity, local wildlife

The DENR classifies Finlayson’s squirrels as an “invasive” species whose presence is “not promoted.” They are known to spread rapidly, even within urban forests and green spaces, where they compete with local wildlife for both food and nesting territory. Since 2022, the DENR-BMB has led efforts to “control and eradicate” the squirrel species from the country.

While primarily frugivorous — animals that consume fruit as their main food source — their diet is broad, consuming tree matter, from bark and sap to seeds and fruits. However, this wide reliance on tree matter does not prevent them from disrupting local ecosystems by attacking birds and raiding nests, according to wildlife trade specialist Emerson Sy in a 2021 report by BusinessMirror.

The same report cited former DENR-BMB director Theresa Lim, who suspected that these invasive squirrels were illegally brought into the country as pets before later being let loose in the wild by their owners.

Under Republic Act No. 9147 or the Wildlife Resources Conservation and Protection Act, the introduction of exotic species, defined as those that do not naturally occur in the country, is prohibited without prior clearance from the secretaries of either or both the DENR and the Department of Agriculture, or their authorized representatives.

While the Philippines has its own squirrel species, they are usually endemic to specific islands, such as Palawan, as well as certain areas in the Visayas and Mindanao. Some of these species include the Northern Palawan tree squirrel, Southern Palawan tree squirrel, Philippine tree squirrel, and the Philippine pygmy squirrel. – Lance Ariel Bustos/Rappler.com

Lance Ariel Bustos is a Rappler intern. He is a third-year political science and Philippine media studies student at De La Salle University Manila, and the current intermedia editor of The LaSallian, DLSU’s official student publication.