Geographic Range
Finlayson's squirrels are native to central Indochina from central Myanmar southeast
through much of Thailand, Lao PDR, and Cambodia to the Mekong Delta in South Vietnam.
In addition, Finlayson's squirrels have been introduced to different locations. For
example, this species has been introduced to towns in Italy. One pair of this species
was introduced into Acqui Terme in the commune of Piedmont in northern Italy in 1982
and also in Maratea in the 1980's. In Asia, this species was introduced to Singapore,
Hamamatsu, and Shizuoka.
- Biogeographic Regions
- palearctic
- oriental
Habitat
Finlayson's squirrels are terrestrial and highly arboreal. They inhabit many forested
habitats, such as dense forest, coconut plantations, and sparse woods. They are known
from forested limestone mountains of central Lao PDR. Finlayson's squirrels spend
most of their time in trees and are rarely seen on the ground.
After the introduction into Maratea, the population expanded to colonize a narrow
belt of woods by the Tyrrhenian coast. It is predicted that the next habitat that
this species will take over is the deciduous forest adjacent to these coastal woods.
- Habitat Regions
- tropical
- terrestrial
- Terrestrial Biomes
- forest
- scrub forest
- mountains
- Other Habitat Features
- urban
- suburban
- agricultural
- riparian
Physical Description
Coat color in Finlayson's squirrels varies according to subspecies and members within
subspecies. The coat color may range from all white, to all red, to all black. Due
to the variability of the coat color of this species, it is often referred to as variable
squirrel.
Males and females can be distinguished from each other by the external scrotum and
testes on the male, and a vulva that appears as a dark dot on a white background on
the female. Females can also be distinguished by 4 visible teats.
On average, the head to body length of females is 191.8 mm. The average tail length
in females is 172.8 mm. For males, the average head to body length is 190.1 mm, and
average tail length is 173.4 mm. The average mass of adults (in both sexes) is 278.0
g. The average head to body length and tail length respectively in adults (in both
sexes) is 212.1 mm and 222.0 mm respectively.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
Reproduction
As a member of the family
Sciuridae
these squirrels have a polygyandrous mating system in which many males can mate with
many females. Males will perform mating calls and mating chases as a part of mating
rituals.
- Mating System
- polygynandrous (promiscuous)
Finlayson's squirrels have three reproductive periods: April, July to August, and
November to December. Females have only 1 to 2 offspring during each one of these
reproduction periods, and females reach sexual maturity at about their 2nd year of
life.
Finlayson's squirrels have a high reproductive rate because sexual maturity is reached
early and the females have a short gestational period.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
Finlayson's squirrels build nests from plant material to care for their young. Females
care for the young. Further research is required to observe details of parental care
in this species.
- Parental Investment
- altricial
- female parental care
-
pre-fertilization
- provisioning
-
protecting
- female
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
Lifespan/Longevity
Limited information is available for the lifespan of Finlayson's squirrels. In captivity,
they are known to survive a maximum of 12.8 years. There is currently no record of
the lifespan of the species in the wild.
Behavior
Finlayson's squirrels spend from 75.9% to 96.3% of their time active, with a major
proportion of that time spent foraging.
Home Range
Communication and Perception
There have been 10 types of vocalizations identified in this species, in particular
in the members that reside in Acqui Terme. They consist of alarm signals in the presence
of
cats
and of
magpies
, male distant calling signals, male close calling signals, male courtship calls (made
of three sequences of emissions with different intervals), mating calls, mother distant
calls, young distant calls, and squeaks. It is likely that they also communicate with
visual and chemical cues.
- Communication Channels
- acoustic
Food Habits
Finlayson's squirrels spend a majority of their active time foraging. Their diet varies
seasonally and regionally. For example, they will feed on bark and buds during the
winter, flowers in the spring, and then mature seeds and fruit between June and October.
In the summer, the squirrels will search for and eat insects.
Finlayson's squirrels feed on a wide variety of trees. Since the majority of their
time is spent in trees, they also spend the majority of their feeding time consuming
tree matter. In Acqui Terme, these squirrels spend 36.5% of their feeding time consuming
bark and sap, 36% seeds and fruits, 11.3% on buds and 6.5% on flowers.
Finlayson's squirrels also cache food. In the urban park areas of Acqui Terme, this
can be observed occasionally when the squirrels store hazelnuts, walnuts, and seeds
given to them by visitors. They store food in nests or scatter them across trees.
Their ability to adapt to a wide range of foods, active foraging skills, and hoarding
behavior are key factors in their ability to survive outside of their native habitat.
- Animal Foods
- insects
- Plant Foods
- wood, bark, or stems
- seeds, grains, and nuts
- sap or other plant fluids
- Foraging Behavior
- stores or caches food
Predation
In Acqui Terme, Finlayson's squirrels interacted with species such as
magpies
,
hooded crows
, and
domestic cats
. They would emit alarm calls when the magpies and crows approached their juveniles
or when cats would approach a tree that they were at. Cats were unsuccessful as predators
and only once was it observed that a cat followed a squirrel up a tree. Predators
in their native range are not reported, but are likely to be arboreal predators, such
as birds, cats, and snakes.
Finlayson's squirrels mostly arboreal lifestyle is an adaptation related to competition
and predator avoidance in its native territory in Indochina.
Ecosystem Roles
As an invasive species, Finlayson's squirrels have a significant impact on native
species where they have been introduced, including Italy and Japan. Since the diet
is comprised of mainly plant matter, it strips many species of trees of its bark.
In Acqui Terme Finlayson's squirrels stripped the bark off of 80% of the 10 species
it found most palatable. In Maratea, the squirrels strip the bark off of these species
of trees:
Ceratonias iliqua
,
Quercus virgiliana
,
Quercus ilex
, and
Olea europea
. Ecosystem roles in their native habitat are not reported, but may include seed dispersal
and acting as an important prey source for arboreal predators.
Economic Importance for Humans: Positive
There have been no studies documenting positive effects of this species on economy.
Members of this species are often sold as domestic pets, especially in Italy.
- Positive Impacts
- pet trade
Economic Importance for Humans: Negative
Finlayson's squirrels have a negative impact on the human economy because they destroy
electric cables and other structures. More study is required to assess the full impact
this species has on humans.
Conservation Status
Finlayson's squirrels are categorized as Least Concern because of their wide distribution
and ability to adapt to a wide range of environments.
Other Comments
Finlayson's squirrels are also called variable squirrels because of their wide range
in coat color.
Additional Links
Contributors
Luqian Liu (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, Tanya Dewey (editor), University of Michigan-Ann Arbor.
- Palearctic
-
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- oriental
-
found in the oriental region of the world. In other words, India and southeast Asia.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- mountains
-
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
- urban
-
living in cities and large towns, landscapes dominated by human structures and activity.
- suburban
-
living in residential areas on the outskirts of large cities or towns.
- agricultural
-
living in landscapes dominated by human agriculture.
- riparian
-
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- polygynandrous
-
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- altricial
-
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
- female parental care
-
parental care is carried out by females
- arboreal
-
Referring to an animal that lives in trees; tree-climbing.
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- acoustic
-
uses sound to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- stores or caches food
-
places a food item in a special place to be eaten later. Also called "hoarding"
- pet trade
-
the business of buying and selling animals for people to keep in their homes as pets.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
References
Bertolino, S., G. Aloise. 2005. Free-Ranging Populations of the Finlayson's Squirrel Callosciurus Finlaysonii (Horsfield,1824)(Rodential, Sciuridae) In South Italy. Hystrix Italian Journal of Mammalogy , 16 (1): 70-74.
Bertolino, S., I. Currado, P. Mazzoglio, G. Amori. 2000. Native and Alien Species of Squirrels in Italy. Hystrix Italian Journal of Mammalogy , 11.2: 65-74.
Bertolino, S., P. Lurz. 2013. Callosciurus squirrels: worldwide introductions, ecological impacts and recommendations to prevent the establishment of new invasive populations.. Mammal Review , 43: 22-33.
Bertolino, S. 2004. Activity Budget and Foraging Behavior of Introduced Callosciurus Finlaysonii (Rodentia, Sciuridae) in Italy. Journal of mammalogy , 85: 254 - 259.
Bertolino, S. 2005. The Application of the European Strategy on Invasive Alien Species: An Example with Introduced Squirrels. Hystrix Italian Journal of Mammalogy , 16: 59-69. Accessed March 06, 2014 at http://www.italian-journal-of-mammalogy.it/index.php/hystrix/article/viewArticle/4343 .
Brown, E., Squirrel Girls, A. Peri, N. Santarosa. 2012. "Sciuridae squirrels" (On-line). Animal Diversity Web. Accessed April 12, 2014 at http://animaldiversity.ummz.umich.edu/accounts/Sciuridae/#aff530c6611542a5bb60cae66f79b2b2 .
Duckworth, J., R. Timmins, M. Parr. 2008. "IUCN Red List of Threatened Species" (On-line). Accessed March 06, 2014 at http://www.iucnredlist.org/details/3596/0 .
Thorington, R. 2012. Squirrels of the World . Baltimore, MD: Johns Hopkins University Press.
Weigel, R. 2005.
Longevity of Mammals in Captivity; from the Living Collections of the World
. Stuttgart: Kleine Senckenberg-Reihe 48.