They may appear to be cute and cuddly. But the Finlayson’s squirrel (Callosciurus finlaysonii), a nonnative species in the Philippines, is now considered an invasive alien species that threatens Luzon.
The proliferation of the Finlayson squirrel species was first reported in Metro Manila as early as 2000. Now, sightings of the species in Batangas and Nueva Ecija raised concern about the proliferation of the species in other parts of Luzon.
The Department of Environment and Natural Resources (DENR) Region IV-A, or Calabarzon area, has confirmed threat posed by the Finlayson’s squirrel in the province of Batangas.
On the other hand, the DENR Region 3 (Central Luzon) has yet to validate the reported sightings of the invasive squirrel in the area.
Whether they are naturally occurring or was just introduced in an area, squirrels are often referred to as nuisance wildlife and they present their own unique set of dangers when it comes to their interaction with humans, according to PestWorld.org.
“They can become aggressive when they feel frightened or threatened,” it says in an article about squirrels posted in its official website.
Squirrels generally look alike and for the untrained eye, it’s hard to distinguish one species from another.
Squirrels are generally small rodents with slender bodies, bushy tails and large eyes, it says in its website.
Their fur is short, soft and silky, and ranges in thickness from species to species and the color of their fur is highly variable. They can be whitish, gray, yellow, red, brown, or even black.
Also known as Variable squirrel because of its variable color and pattern, the upper side of the Finlayson’s squirrel is of a darker color than the underside, according to the Biodiversity Management Bureau (BMB).
They thrive naturally in lowland forests, open woods, plantations, and even in dense forests.
The species is highly tolerant of degraded and fragmented habitats. Like other squirrel species, Finlayson’s squirrel is a canopy-dweller and feeds mainly on fruit and crops.
While it is native to Thailand, Myanmar, Laos, Cambodia, and Vietnam, the Finlayson’s squirrel has been introduced to other countries such as Italy, Japan, and Philippines where it is now considered an invasive alien species.
According to the DENR-BMB, there’s no record of the lifespan of the species in the wild, but in captivity, they are known to survive a maximum of 12 years.
These squirrels are ultimate survivors and threaten other species in the Philippines, including its very own native species.
Native squirrel species
The DENR-BMB said there are nine recorded native species of squirrels in the Philippines. But they are mostly found in Palawan and Mindanao. Luzon has no native species on record.
These are the Philippine pygmy squirrel (Exilisciurus concinnus), Northern Palawan tree squirrel (Sundasciurus juvencus), Southern Palawan tree squirrel (Sundasciurus steeri), Palawan flying squirrel (Hylopetes nigripe), Palawan montane tree squirrel (Sundasciurus rabori), Philippine tree squirrel/ Mindanao tree squirrel (Sundasciurus philippinensis), Mindanao flying squirrel (Petinomys crinitus), Culion tree squirrel (Sundasciurus moellendorffi) and the Busuanga tree squirrel (Sundasciurus hoogstraali).
All these species are endemic to the Philippines, particularly in some islands of Palawan and in Mindanao faunal region.
The Finlayson’s squirrels have successfully established breeding populations in Metro Manila, specifically in the areas with sprawling tree vegetation, like in Dasmariñas Village, Makati City; Ninoy Aquino Parks and Wildlife Center, Quezon City; and Alabang Hills Village, Muntinlupa City.
The invasive squirrels had been documented to feed on fruits, vegetables, and young shoots of coconut trees. However, they can also attack smaller animals, including birds and their eggs.
Since there are no known native squirrels in Luzon, it was widely believed that the invasive species was introduced in the Philippines through the illegal pet trade.
DENR Calabarzon Regional Executive Director Nilo Tamoria through a Zoom meeting on June 9, confirmed to the BusinessMirror that the Finlayson’s squirrels have also established breeding populations in Batangas.
“There was a turn-over last November 9, 2020. There were six heads of squirrels. Out of six, upon turnover, one is already weak. The squirrels were turned over by CENRO Calaca to the Regional Wildlife Rescue Center of DENR Region IV-A,” Tamoria said.
“The caretaker of the farm captured the squirrels using trap for rodents,” he said.
In Central Luzon, the DENR Regional Information Officer, Don Guevarra told the BusinessMirror in an interview over Messenger on June 9 that there is no confirmed or verified report of a breeding population existing in the region.
“We still need to verify with the PENROs (Provincial Environment and Natural Resource Office) if there are indeed squirrels in their area,” he said.
Creeping population; threat to farms, wildlife
DENR Undersecretary for Special Concerns Edilberto Leonardo, also the concurrent DENR-BMB director, in a telephone interview confirmed that the invasive squirrel are now creeping and establishing breeding populations in Luzon.
Interviewed over the phone on June 15, Leonardo said the squirrels must be recovered but it will require the help of the communities. He appealed to communities to help capture the squirrels and turn them over to the DENR for proper handling and disposal, if necessary.
“We cannot just extinguish them in the wild because we don’t want other species to be affected, like rodents,” he said.
Leonardo said the potential economic damage to farms and agricultural areas of invasive squirrels will be enormous, including damage to the country’s biodiversity.
“It will affect our biodiversity,” he said.
In case of population outbreak, the DENR may take appropriate actions, but in a humane way,” he said.
He said communities can help by trapping the squirrels and turning them over to the DENR.
“If the countries where they naturally occur accept them back, we will turn them over. If not, we may accept them and keep them in our rescue center for proper disposal,” he said.
‘Don’t shoot them’
Leonardo advises those who wish to hunt them like the pest they are to do it at their own risks. He reminded them that Republic Act 9147, otherwise known as the Wildlife Resources Conservation and Protection Act, prohibits such cruelty to animals.
“It is illegal to hunt them in the wild,” he said.
He said the best way is to trap them, as doing so will help prevent those captured from further breeding.
“We need to prevent the spread of their population because they might reach and start to invade our Protected Areas,” he said.
According to the official, the invasive squirrels affecting Metro Manila and other areas in Luzon was a result of their release into the wild.
He warned pet lovers not to release their pets into the wild as they may become a pest in the future, citing the case of the invasive squirrels that have established breeding populations in the wild.
Emerson Sy, a wildlife trafficking specialist, said the proliferation of squirrels in Metro Manila is now spreading fast. “There are also squirrels now in Rizal Province,” he told the BusinessMirror via Messenger on June 16.
A squirrel pair, he said, was recently monitored being sold online. A pair of the Finlayson’s squirrel can fetch P2,500 to P6,000 in the domestic market. He said some of those being sold may have been captured from the wild.
According to Sy, there’s a need to tighten watch on the illegal pet trade as he confirmed that unscrupulous traders are trading the Finlayson’s squirrels, physically, and online.
He warned that these pet lovers may eventually get tired and release the squirrels into the wild, thereby establishing a viable squirrel population in the area.
“It would be great if the BMB can come up with a policy on invasive species. For instance, there is a special order on the collection of the invasive Chinese softshell turtle. We are now exporting the species for a few years now,” he said.
According to the DENR-BMB, like other rodents, Finlayson’s squirrels are prolific breeders. They have a high reproductive rate because sexual maturity is reached early. Females reach sexual maturity in 2 years and that they have a short gestational period.
Female squirrels are likely to have multiple litters per year. Females have only 1 to 2 offspring during reproduction periods but the species has a polygynous mating system in which both males and females have multiple mating partners during a breeding season.
The DENR-BMB said they feed on agricultural crop s, hence it may cause potential loss of income to farmers.
They had been documented to feed on fruits (e.g. lanzones, durian, banana, santol, duhat, mango), vegetables (e.g. patola, patani) and young shoots of coconut trees.
Besides being a potential pest to agriculture, Finlayson’s squirrel also poses a potential threat to the Philippine environment, including: loss of native biodiversity (e.g., birds, lizards, and insects) due to predation and competition; spread of non-native diseases; and invasion of protected areas resulting in disruption of ecosystem services. Protected areas and watersheds nearest to Metro Manila are exposed to the highest risk of exotic squirrel invasion.
As early as 2014, the BMB has been trying to fight the proliferation of the invasive squirrels in Metro Manila, but to no avail.
The BusinessMirror learned from sources at the DENR that a Department Administrative Order along with a Technical Bulletin would soon be released to eliminate the invasive squirrels.
Until then, however, these cute and cuddly but pesky rodents will continue to breed under the protection of the Wildlife Act.