Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide


Callosciurus finlaysonii
(Finlayson's squirrel)



Callosciurus finlaysonii (Finlayson's squirrel)


  • Last modified
  • 20 November 2018
  • Datasheet Type(s)
  • Invasive Species
  • Host Animal
  • Preferred Scientific Name
  • Callosciurus finlaysonii
  • Preferred Common Name
  • Finlayson's squirrel
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Chordata
  •       Subphylum: Vertebrata
  •         Class: Mammalia
  • Summary of Invasiveness
  • C. finlaysonii is a squirrel native to Thailand, Myanmar, Laos, Cambodia and Vietnam. It has been introduced to Italy (Be...

  • Principal Source
  • Draft datasheet under review

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Callosciurus finlaysonii (Finlayson's squirrel or variable squirrel); adult on tree trunk, feeding. Bangkok, Thailand. November, 2012. (image rotated 90° counter-clockwise)
CaptionCallosciurus finlaysonii (Finlayson's squirrel or variable squirrel); adult on tree trunk, feeding. Bangkok, Thailand. November, 2012. (image rotated 90° counter-clockwise)
Copyright©Thai National Parks - CC BY-SA 3.0
Callosciurus finlaysonii (Finlayson's squirrel or variable squirrel); adult on tree trunk, feeding. Bangkok, Thailand. November, 2012. (image rotated 90° counter-clockwise)
AdultCallosciurus finlaysonii (Finlayson's squirrel or variable squirrel); adult on tree trunk, feeding. Bangkok, Thailand. November, 2012. (image rotated 90° counter-clockwise)©Thai National Parks - CC BY-SA 3.0


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Preferred Scientific Name

  • Callosciurus finlaysonii (Horsfield, 1824)

Preferred Common Name

  • Finlayson's squirrel

Other Scientific Names

  • Sciurus finlaysonii Horsfield 1823

International Common Names

  • French: écureuil de Finlayson

Local Common Names

  • Germany: Finlayson-Hornchen
  • Italy: scoiattalo di Finlayson; scoiattolo variabile

Summary of Invasiveness

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C. finlaysonii is a squirrel native to Thailand, Myanmar, Laos, Cambodia and Vietnam. It has been introduced to Italy (Bertolino et al. 2000; Aloise and Bertolino, 2005Rima et al. 2007), Singapore and Japan (Oshida et al., 2007; Kuramoto et al. 2012), and is considered invasive in Italy and Japan. It is a species of lowland forests (Moore and Tate, 1965) as well as open woods and coconut plantations (Lekagul and McNeely, 1988). In Italy it is known to inhabit urban parks and pine woodlands, and to feed on Ceratonia siliquaPinus halepensis,P. pinea, Quercus virgiliana, Q. ilex, Olea europea and all kinds of fruit (Aloise and Bertolino, 2005).. Its presence in Italy has also been linked to severe damage as a result of bark-stripping behaviour of both deciduous and conifer trees, which can in severe cases kill trees (Aloise and Bertolino 2005; Rima et al., 2007; Mori et al., 2016).C. finlaysonii is listed on the IUCN Red list (IUCN, 2014) as 'least concern' due to its wide distribution.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Chordata
  •             Subphylum: Vertebrata
  •                 Class: Mammalia
  •                     Order: Rodentia
  •                         Family: Sciuridae
  •                             Genus: Callosciurus
  •                                 Species: Callosciurus finlaysonii

Notes on Taxonomy and Nomenclature

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The generic name Callosciurus is from the Greek 'callo' for beautiful, 'skia' for shadow, and 'oura' for tail (Borror, 1960; Lurz et al., 2005).

There have been no recent taxonomic revisions; but see Steppan et al. (2004) for an assessment of the phylogeny of squirrels using two nuclear genes (c-myc and RAG1). Their results show the tribe Callosciurini to be a monophyletic group, but suggested a re-ordering of subfamilies and tribes within the family Sciuridae, including the creation of the subfamily Callosciurinae containing the tribe Callosciurini and the tribe Funambulini.

Species taxonomy was initially revised by Moore and Tate (1965) and then revised and expanded to include C. finlaysonii ferrugineus by Corbet and Hill (1992). For differences between subspecies, see Detection and Inspection.


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Coat colour is highly variable (for descriptions of subspecies see Detection and Inspection; for detailed coat colour descriptions see Moore and Tate (1965) and Corbet and Hill (1992). Timmins and Duckworth (2008) provided descriptions for subspecies in Laos). Morphological details of adult C. finlaysonii are shown in the table below.

Table 1: Morphological data from different studies for body mass (g), head to body length (mm), and tail length for adult males (M), females (F) and individuals of unknown sex (U). Sample sizes where known are given in brackets after the values.


Weight (g)







190.1 (14)

173.4 (14)

Hayssen, 2008a

Average data



191.8 (13)

172.8 (13)

Hayssen, 2008a

Average data











Moore and Tate, 1965

Range across subspecies





Corbet and Hill, 1992

Range across subspecies


278 (2)



Hayssen, 2008a






Kitamura et al., 2004


Moore (1961) noted the presence of three pairs of mammae, typical for Callosciurus species in the Indo-Chinese subregion. Observed hind-foot length range across subspecies are 44-58 mm (Moore and Tate, 1965) and 46.99-53.34 mm (Blanford 1888-1891). C. finlyasonii williamsoni and C. finlaysonii bocourti had the greatest reported skull length at 52.2 and 52.7 mm respectively and C. finlaysonii finlaysonii the shortest at 45.5mm (Moore and Tate, 1965). Corbet and Hill (1992) gave the range of skull length for this species as 44-57 mm.

The baculum in the subfamily Callosciurus is unique and characterised by a sharp-edged accessory blade attached to its dorsal surface (Corbet and Hill, 1992). The baculum of C. finlaysonii is long and slender (Corbet and Hill, 1992).


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C. finlaysonii is native to Cambodia, Laos, Myanmar, Thailand and Vietnam. Corbet and Hill (1992) and Thorington et al. (2012) provided information on mainland and insular subspecies distributions in Thailand, Myanmar, Burma, Laos and Cambodia (see Detection and Inspection). C. finlaysonii has been introduced to Singapore (Thorington et al., 2012), Italy (Bertolino et al., 2000) and Honshu, Japan (Kuramoto et al., 2012). No source references are provided for the introduction to Singapore and the current status of this population is unclear, although it was listed as introduced by the Singapore Government (2014).

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes


CambodiaPresentNativeCorbet and Hill, 1992; Thorington et al., 2012Subspecies C. f. annellatus and C. f. cinnanoneus
JapanPresentPresent based on regional distribution.
-HonshuPresentIntroduced Invasive Kuramoto et al., 2012
LaosPresentNativeThorington et al., 2012
MyanmarPresentNativeCorbet and Hill, 1992; Thorington et al., 2012Subspecies C. f. ferrugineus; geographically isolated
SingaporePresentIntroducedThorington et al., 2012
ThailandPresentNativeCorbet and Hill, 1992; Thorington et al., 2012Mainland and islands of Si Chang, Phai, Tut
VietnamPresentNativeCorbet and Hill, 1992; Thorington et al., 2012Subspecies C. f. germaini, C. f. harmandi on islands of Phu Quoc and Condor respectively


ItalyPresentIntroduced Invasive Thorington et al., 2012; Bertolino and Lurz, 2013See text section

History of Introduction and Spread

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No detailed information is available for the introductions of C. finlaysonii in Singapore or Japan, although Yanagawa (2000) did report the sale of squirrels as pets in Japan. In Italy, four individuals were released in a 2 ha urban park at Aqui Terme, northwest Italy, in 1981 (Bertolino et al., 1999), and 3-4 pairs of C. finlaysonii were introduced in southern Italy at Maratea, Basilicata region, in the mid-1980s (Rima et al., 2007). Bertolino et al. (1999) identified the subspecies in northwest Italy as C. finlaysonii bocourti. Both populations are reported to be increasing, the one at Maratea exponentially (Bertolino et al., 2000).

There was initially some uncertainty whether the species was introduced to Japan. Oshida et al. (2007) carried out a preliminary genetics study to determine the origin of introduced Callosciurus to Japan. Their findings identified two genetic lineages (A and B). Lineage A was found to be related to C. finalysoni. Precise species identifications, however, proved difficult due to the high level of variability in Callosciurus species and subspecies, and the occurrence of hybridisation and gene introgression between subspecies and species. However, the introduction of C. finlaysonii to Japan was confirmed by further work by Kuramoto et al. (2012), using mitochondrial DNA. All 83 individuals from the Callosciurus population at Hamamatsu, Shizuoka Prefecture, tested had C. finalysonii haplotypes. The 'CfJ1' haplotype, present in 25% of the animals, has also been reported from C. finlaysonii boonsongi in north-eastern Thailand, and the authors speculate that the population in Japan may have been imported from Thailand via Bangkok (Kuramoto et al., 2012).


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Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Italy 1981-1986 Ornamental purposes (pathway cause) Yes No Bertolino et al. (2000)
Japan Thailand   Yes No Kuramoto et al. (2012) C finlaysonii traded as pets around 2000; mtDNA haplotype match C. f. boonsongi from north-eastern Thailand

Risk of Introduction

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In both Italy and Japan, where C. finlaysonii is considered invasive, the pet trade seems a high risk pathway for introduction. Experience with tree squirrel species has shown that animals obtained through the pet trade are a prime source for continued human-mediated, deliberate releases that greatly assist in the successful spread of the species involved (e.g. Martinoli et al., 2010; Bertolino and Lurz, 2013). No information is available from Singapore.


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There are few detailed descriptions on habitat preferences aside from broad descriptions that link the species to a wide range of forest habitats, such as open woods, coconut plantations, and dense forest (Lekagul and McNeely, 1988). Specific examples of habitat include moist evergreen forests of elevations between 600-800 m in Khao Yai National park, Thailand (Suzuki et al., 2006; see also Kitamura et al. 2004), mixed deciduous and dry dipterocarp forest in Mae Hong Son Province, northern Thailand at elevations of 800-1200 m (Watanaratchakit and Srikosamatara, 2006), and lowland mixed forests (especially fruit trees) on the island of Phu Quoc, Vietnam (Abramov et al., 2007).

Duckworth et al. (2008) considered C. finlaysonii highly tolerant of degradation and fragmentation.

Habitat List

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Terrestrial – ManagedManaged forests, plantations and orchards Secondary/tolerated habitat
Urban / peri-urban areas Present, no further details
Terrestrial ‑ Natural / Semi-naturalNatural forests Principal habitat

Biology and Ecology

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Chromosomes have been described by Nadler et al. (1975): C. finlaysonii has 2n = 40, and the karyotype is comprised of six pairs of metacentric, 10 of submetacentric and three pairs of acrocentric autosomes, one of which bearing satellites (Nadler et al., 1975). A re-examination by Tanomtong et al. (2009) based on the subspecies C. finlaysonii bocourti supported the number of diploid chromosomes being 2n=40, and provided more detail in the description of autosomes: four large metacentric, four large submetacentric, 14 large acrocentric, two medium telocentric, four small metacentric, six small acrocentric and four small telocentric chromosomes (Tanomtong et al., 2009).

Oshida et al. (2001) studied the molecular phylogeny of five squirrel species in the genus Callosciurus based on cytochrome B sequences. Their findings indicated two lineages, one containing C. erythraeus, C. caniceps and C. finlaysonii, and the other containing C. nigovittatus and C. prevostii. Whilst these results support Moore's (1961) division of Callosciurus species, based on morphological characteristics, into a mainland and a Sundaland unit, Oshida et al. (2001) did not rule out the possibility of other geographical lineages pending a comprehensive analysis of all 15 described species of Callosciurus.

Reproductive biology

Reproductive behaviour and mating strategies unknown. One reported litter size of two (Hayssen, 2008b).

Activity patterns

In Thailand C. finlaysonii is diurnal and probably most active in the afternoon (Suzuki et al., 2006).

Nutrition and seed dispersal

Known dietary items include tree seeds and fruits (Kitamura et al., 2004; 2006; Rima et al., 2007). Kitamura et al. (2004; 2006) suggested that C. finlaysonii eats Canarium euphyllum fruits and seeds, and is a short distance seed disperser for Aglaia spectabilis in moist evergreen forests in Thailand.


D'Ovidio et al. (2014) reported finding eggs of the parasitic flatworm Dicrocoelium dendriticum in two pet C. finlaysonii in Italy.


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Af - Tropical rainforest climate Preferred > 60mm precipitation per month
Cs - Warm temperate climate with dry summer Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers

Notes on Natural Enemies

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There is no specific mention of particular predators in the literature (see Research needs); however, key natural enemies are likely to be small to medium-sized mammalian predators, birds of prey and snakes.

Means of Movement and Dispersal

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The pet trade appears a high-risk pathway for long distance dispersal and introductions of C. finlaysonii beyond its natural range.

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Pets and aquarium species Yes Bertolino and Lurz, 2013; Yanagawa, 2000

Economic Impact

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There are no detailed accounts of economic impacts for C. finlaysonii across its native range, although the species' presence in coconut plantations (Lekagul and Ncneely, 1988) may suggest the potential for damage.

In Italy, C. finlaysonii has been linked to extensive, if currently localized, damage to trees through bark-stripping behaviour. The animals strip the bark of trees to obtain access to sap bearing tissue. Damage that girdles the stems or trunk can kill parts of the tree, or even the whole tree if this happens on the main trunk. Bark-stripping damage can also facilitate secondary infections (such as fungal infections) and reduce the economic value of timber. Affected tree species in Italy include Certonia siliqua, Quercus virgiliana, Q. ilex, Olea europea and Pinus halepensis (Aloise and Bertolino, 2005; Mori et al., 2016).

Environmental Impact

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In Italy the localized presence of C. finalysonii is linked to severe damage to trees through bark-stripping behavior, with an estimated 80% of trees damaged in the urban park where they were first introduced in northern Italy. Damage to trees has also been recorded in the other area of introduction in southern Italy. In severe cases extensive damage can kill trees (Bertolino et al., 2000).

Introduced populations in Italy, Japan and Singapore are still localized and often there is a lag effect with respect to population expansion linked to squirrel introductions with small founder sizes (e.g. Lurz et al., 2001; Wood et al., 2007). Broader biodiversity or ecosystem impacts tend to occur once the population expands. Both in Italy and in Japan Callosciurus squirrels are expanding their range and are considered invasive.

Tree squirrel and other rodent introductions have been linked to the introduction of novel parasites and diseases including the spread of zoonotic disease (e.g. Khodakevich et al., 1986; Langkop et al., 2003; Dozière et al. 2010; Romeo et al., 2014). Whilst there are currently no data for C. finlaysonii finlaysonii due to a lack of studies, the risk of disease transmission, and introduced individuals acting as vectors for parasites and diseases that can harm native wildlife (and potentially humans) should not be ignored.

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Is a habitat generalist
  • Capable of securing and ingesting a wide range of food
  • Highly mobile locally
  • Benefits from human association (i.e. it is a human commensal)
  • Has high reproductive potential
Impact outcomes
  • Damaged ecosystem services
  • Negatively impacts forestry
  • Reduced native biodiversity
Impact mechanisms
  • Competition - monopolizing resources
  • Competition
  • Pest and disease transmission
Likelihood of entry/control
  • Highly likely to be transported internationally deliberately
  • Difficult to identify/detect in the field
  • Difficult/costly to control

Uses List

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  • Botanical garden/zoo
  • Research model
  • Sport (hunting, shooting, fishing, racing)


  • Skins/leather/fur

Detection and Inspection

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Based on Corbet and Hill (1992) the following nine mainland and seven island subspecies have been described (see also Thorington and Hoffmann, 2005):


C. finlaysonii nox - from a small coastal area of Thailand, near Cape Liant. Coat is entirely black.

C. finlaysonii cinnamomeus (encompasses subspecies C. finlaysonii splendens and C. finlaysonii herberti) - from south-east Thailand and south-west Cambodia. Coat is all red or with a small amount of olive agouti on head and limbs.

C. finlaysonii annellatus - from central and east Cambodia, and the south of Laos. Coat mainly reddish brown with a cream band near the base of the tail.

C. finlaysonii williamsoni - from Laos. Coat red to orange above, sharply demarcated from chestnut below, tail maroon.

C. finlaysonii boonsongi - from north-east Thailand. Coat mostly black or very dark, with white rim on ear and greater venter. Note a small proportion of creamy white and red individuals occur.

C. finlaysonii bocourtii (includes leucogaster, leucocephalus, floweri, tachardi, prachin, rajasima and cockerelli) - from central Thailand. Coat on dorsum black, rest including head white or cream, entirely cream in some peripheral populations.

C. finlaysonii sinistralis (includes dextralis, lylei and grulei) - from central to north-west Thailand. Coat mostly red but dorsum reddish agouti and a cream band on the tail.

C. finlaysonii menamicus - from north-central Thailand. Coat all red with buffy white tip to tail.

C. finlaysonii ferrugineus - from Burma. As C. finlaysonii menamicus but geographically isolated

Two potentially unnamed forms were reported by Timmins and Duckworth (2008) from Laos (see also Evans et al., 2000).


C. finlaysonii finlaysonii - from Si Chang, Thailand. Coat all white, tinged yellow especially on back.

C. finlaysonii folletti - from Phai, Thailand. Coat white with grey hair bases showing.

C. finlaysonii trotteri - from Lan, Thailand. Coat grey with white tail and blackish feet.

C. finlaysonii frandseni - from Chang, Thailand. Coat red with grey flanks.

C. finlaysonii albivexilli - from Tut, Thailand. Coat black, but with white tip to tail. Thorington et al. (2012) gave Koh (= island) Kut as location.

C. finlaysonii harmandi (includes C. finlaysonii pierrei) - from Phu Quoc, Vietnam. Coat dark reddish brown above, light orange-red below, tail greyish white. Abramov et al. (2007) also notes that the fluffy, light gray tail has length white under-hairs.

C. finlaysonii germaini - from Condor I, Vietnam. Coat all black.

Similarities to Other Species/Conditions

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Corbet and Hill (1992) noted that ‘the species is so variable that no simple diagnosis applies.’ Across parts of its range it is sympatric with C. erythraeus and may be confused with this species. For example, C. finlyasonii sinistralis can only be distinguished from C. erythraeus atrodorsalis by the pale base of the tail. Moore and Tate (1965) provided a key to distinguish Callosciurus from other sympatric squirrel genera and describe the following characteristics:

  1. The least inter-orbital breadth exceeds the greatest length of the nasal bone.
  2. There are no pronounced longitudinal stripes on the back (although there may be on sides and venter)
  3. There is a single, unforked bony septum across the chamber of the auditory bulla.
  4. The 3rd upper molar is present.
  5. The coronoid process of the mandible is high and falcate.
  6. The upper edge of the infra-orbital foramen is well separated from the maxillo-premaxil-larysuture
  7. The baculum consists of two separate parts, a shaft and a blade.
  8. Orbit length exceeds 13 mm.
  9. The supra-orbital notches are obsolescent.

Callosciurus is distinguished from the other genera of squirrels of the Indian and Indochinese subregions by the above characters as follows: from Ratufa by 3, 4, 6 and 7; Funambulus by 2, 5 and 7; Tamiops by 2 and 8; and Dremonys by 1.

Prevention and Control

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C. finlaysonii is considered an invasive alien species where it has been introduced outside its natural range. Timmins and Duckworth (2008) alluded to an eradication plan for C. finlaysonii finlaysonii in Singapore, citing Lee BPY-H (in prep), but no further information could be found. In Italy, Bertolino and Genovesi (2005) discussed measures for C. finlaysonii control with respect to the wider European strategy on invasive alien species.

Tree squirrels can be highly successful invaders with only few individuals needed for successful establishment (e.g. Bertolino and Genovesi, 2005; Wood et al., 2007) and in many ways represent an alien species conundrum (Bertolino and Lurz, 2013). By the time small founder populations expand sufficiently and their behaviour (such as competition with native species, damage to trees and crops, and being a vector for disease or parasites) is considered a problem, it is often too late for effective control or eradication due to logistic, economic or political reasons. Squirrels have an innate appeal and are often fed by members of the public where they occur in urban or suburban areas. Experience in Italy (Bertolino S, pers. comm.) has shown that any management action needs to include monitoring (to assess distribution and effectiveness of management actions; see Gurnell et al. (2009) for methods), as well as measures to increase public awareness and understanding with respect to the economic and conservation problems and dangers of introduced invasive species.

Gaps in Knowledge/Research Needs

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There is a dearth of information with respect to ecology (e.g. function of species in ecosystem, potential role as disperser of seeds), behaviour (e.g. dispersal, mating, foraging), life history (mortality, fecundity), population dynamics in different habitat types, parasites and diseases (and potential as vector for zoonotic diseases), as well data on population trends for known subspecies across Myanmar, Thailand, Laos, Cambodia and Vietnam.

Given the huge variability in described forms, the reports of as yet unnamed forms (Evans et al., 2000; Timmins and Duckworth, 2008), and the suggestion of hybridisation with closely related Callosciurus species, a systematic, comprehensive review of this species using morphological and genetic approaches is highly desirable.


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Abramov AV, Kalinin AA, Morozov PN, 2007. Mammal survey on Phu Quoc Island, southern Vietnam. Mammalia, 71:40-46.

Aloise G, Bertolino S, 2005. Free-ranging population of the Finlayson's squirrel Callosciurus finlaysonii (Horsfield 1824) (Rodentia, Sciuridae) in South Italy. Hystrix, 16:70-74.

Bertolino S, Currado I, Mazzoglio PJ, 1999. Finlayson (variable) Squirrel Callosciurus finlaysonii in Italy, Mammalia, 63(4):522-525

Bertolino S, Currado I, Mazzoglio PJ, Amori G, 2000. Native and alien squirrels in Italy. Hystrix It. J. Mamm, 11:49-58.

Bertolino S, Genovesi P, 2005. The application of the European strategy on invasive alien species: an example with introduced squirrels. Hystrix It. J. Mamm. (n.s.), 16:59-69.

Bertolino S, Lurz PWW, 2013. Callosciurus squirrels: worldwide introductions, ecological impacts and recommendations to prevent the establishment of new invasive populations. Mammal Review, 43(1):22-33.

Bertolino S, Mazzoglio PJ, Vaiana M, Currado I, 2004. Activity budget and foraging behavior of introduced Callosciurus finlaysonii (Rodentia, Sciuridae) in Italy. Journal of Mammalogy, 85(2):254-259.

Blanford WT, 1891. Mammalia. London, UK: Taylor and Francis, 375.

Borror DJ, 1960. Palo Alto, Calif. N-P Publications, v+134 pp.

Corbet GB, Hill JE, 1992. The mammals of the Indomalayan region: a systematic review. Oxford, UK: Oxford University Press, 488 pp.

d'Ovidio D, Rinaldi L, Ianniello D, Donnelly TM, Pepe P, Capasso M, Cringoli G, 2014. FLOTAC for diagnosis of endo-parasites in pet squirrels in southern Italy. Veterinary Parasitology, 200(1/2):221-224.

Dozières A, Pisanu B, Gerriet O, Lapeyre C, Stuyck J, Chapuis JL, 2010. Macroparasites of Pallas's squirrels (Callosciurus erythraeus) introduced into Europe. Veterinary Parasitology, 172(1/2):172-176.

Duckworth JW, Timmins R, Parr M, 2008. Callosciurus finlaysonii. The IUCN Red List of Threatened Species 2008: e.T3596A9964363

Evans TD, Duckworth JW, Timmins RJ, 2000. Field observations of larger mammals in Laos, 1994-1995. Mammalia, 64(1):55-99.

Gurnell J, Lurtz P, McDonald R, Pepper H, 2009. Practical techniques for surveying and monitoring squirrels. Practice Note - Forestry Commission, No.011:12 pp.

Hayssen V, 2008. Patterns of body and tail length and body mass in Sciuridae. Journal of Mammalogy, 89:852-873.

Hayssen V, 2008. Reproductive effort in squirrels: Ecological, phylogenetic, allometric, and lattitudinal patterns. Journal of Mammalogy, 89:582-606.

IUCN, 2014. The IUCN Red List of Threatened Species.

Khodakevich L, Jezek Z, Kinzanzka K, 1986. Isolation of monkeypox virus from wild squirrel infected in nature., Lancet, 327(8472):98-99 .

Kitamura S, Suzuki S, Yumoto T, Poonswad P, Chuailua P, Plongmai K, Maruhashi T, Noma N, Suckasam C, 2006. Dispersal of Canarium euphyllum (Burseraceae), a large-seeded tree species, in a moist evergreen forest in Thailand. Journal of Tropical Ecology, 22(2):137-146.

Kitamura S, Suzuki S, Yumoto T, Poonswad P, Chuailua P, Plongmai K, Noma N, Maruhashi T, Suckasam C, 2004. Dispersal of Aglaia spectabilis, a large-seeded tree species in a moist evergreen forest in Thailand. Journal of Tropical Ecology, 20(4):421-427.

Kuramoto T, Torii H, Ikeda H, Endo H, Rerkamnuaychoke W, Oshida T, 2012. Mitochondrial DNA sequences of Finlayson's squirrel found in Hamamatsu, Shizuoka Prefecture, Japan. Mammal Study, 37:63-67.

Langkop CW, Austin C, Dworkin M, Kelly K, Messersmith H, Teclaw R, Howell J, Michael J, Pontones P, Pezzino G, Hansen GR, Wegner MV, Kazmierczak JJ, Williams C, Croft DR, Ahrabi-Fard S, Will L, Bostrom HH, Davis JP, Fleischauer A, Sotir M, Huhn G, Kanwal R, Kile J, Sejvar J, 2003. Multistate outbreak of monkeypox - Illinois, Indiana, Kansas, Missouri, Ohio, and Wisconsin, 2003. Morbidity and Mortality Weekly Report, 52(24):561-563.

Lekagul B, McNeely JA, 1988. Mammals of Thailand. Bangkok, Thailand: Darnsutha Press.

Lurz PWW, Gurnell J, Magris L, 2005. Sciurus vulgaris. Mammalian Species, 769:1-10.

Lurz PWW, Rushton SP, Wauters LA, Bertolino S, Currado I, Mazzoglio P, Shirley MDF, 2001. Predicting grey squirrel expansion in North Italy: a spatially explicit modelling approach. Landscape Ecology, 16(5):407-420.

Martinoli A, Bertolino S, Preatoni DG, Balduzzi A, Marsan A, Genovesi P, Tosi G, Wauters LA, 2010. Headcount 2010: The multiplication of the grey squirrel introduced in Italy. Hystrix, 21:127-136.

Moore JC, 1961. Geographic variation in some reproductive characteristics of diurnal squirrels. Bulletin of the American Museum of Natural History, 122:1-32.

Moore JC, Tate GHH, 1965. A study of the diurnal squirrels, Sciurinae, of the Indian and Indochinese subregions. Fieldiana Zool, 48:1-351.

Mori E, Mazzoglio PJ, Rima P, Aloise G, Bertolino S, 2016. Bark-stripping damage by Callosciurus finlaysonii introduced in Italy, Mammalia, 80(5):507-514

Nadler CF, Hoffmann RS, Hight ME, 1975. Chromosomes of three species of Asian tree squirrels, Callosciurus (Rodnetia, Sciuridae). Experientia, 31:166-167.

Oshida T, Torii H, Lin L-K, Lee J-K, Chen Y-J, Endo H, Sasaki, M, 2007. A preliminary study on origin of Callosciurus squirrels introduced into Japan. Mammal Study, 32:75-82.

Oshida T, Yasuda M, Endo H, Hussein NA, Masuda R, 2001. Molecular phylogeny of five squirrel species of the genus Callosciurus (Mammalia, Rodentia) inferred from cytochrome b gene sequences., Mammalia, 65(4):473-482

Rima P, Aloise G, Cagnin M, Wauters L, 2007. The use of species-specific cone remains of sympatric arboreal rodents to monitor their distribution. Italian Journal of Zoology, 74:289-296.

Romeo C, Wauters LA, Ferrari N, Lanfranchi P, Martinoli A, Pisanu B, Preatoni DG, Saino N, 2014. Macroparasite fauna of alien grey squirrels (Sciurus carolinensis): composition, variability and implications for native species. PLoS ONE, 9(2):e88002.

Singapore Government, 2014. Mammal species. National Parks.

Steppan SJ, Stolz BL, Hoffmann RS, 2004. Nuclear DNA phylogeny of the squirrels (Mammalia: Rodentia) and the evolution of arboreality from c-myc and RAG1. Molecular Phylogenetics and Evolution, 30:703-719.

Suzuki S, Kitamura S, Kon M, Poonswad P, Chuailua P, Plongmai K, yumoto T, Noma N, Maruhashi T, Wohandee P, 2006. Foraging activity patterns of frugivorous or omnivorous animals on the forest floor of a tropical seasonal forest in Thailand with reference to seasonal changes. Natural History Bulletin of the Siam Society, 54:177-194.

Tanomtong A, Khunsook S, Jantarat S, Supanuam P, Kenthao A, Kaewsri S, 2009. Standardized karyotype and idiogram of the variable squirrel, Callosciurus finlaysoni bocourti (Milne-Edwards, 1867) by conventional staining technique. Journal of Wildlife in Thailand, 16:83-93.

Thorington Jr RW, Koprowski JL, Steele MA, Whatton JF, 2012. Squirrels of the World. Baltimore, USA: The Johns Hopkins University Press.

Thorington RW, Hoffmann RS, 2005. Family Sciuridae. In: Mammal Species of the World. A Taxonomic and Geographic Reference, 2 [ed. by Wilson, D. E.\Reeder, D. M.]. Baltimore, USA: Johns Hopkins University Press, 813-818.

Timmins RJ, Duckworth JW, 2008. Diurnal squirrels (Mammalia Rodentia Sciuridae) in Lao PDR: distribution, status and conservation. Tropical Zoology, 21(1):11-56.

Wattanaratchakit N, Srikosamatara S, 2006. Small mammals around a Karen village in northern Mae Hong Son province, Thailand: abundance, distribution and human consumption. Natural History Bulletin of the Siam Society, 54:195-207.

Wilson DE, Reeder DM, 2005. Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed.). Baltimore, Maryland, USA: Johns Hopkins University Press, 2142 pp.

Wood DJ, Koprowski JL, Lurz PWW, 2007. Tree squirrel introduction: A theoretical approach with population viability analysis. Journal of Mammalogy, 88:1271-1279.

Yanagawa H, 2000. Alien squirrels introduced to Japan as a pet. Sciurid Information, 7:2-3.

Links to Websites

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GISD/IASPMR: Invasive Alien Species Pathway Management Resource and DAISIE European Invasive Alien Species Gateway source for updated system data added to species habitat list.
Global register of Introduced and Invasive species (GRIIS) source for updated system data added to species habitat list.
IUCN Red List
Singapore Government, National Parks: mammal list

Principal Source

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Draft datasheet under review


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11/09/14 Original text by:

Peter Lurz, Royal School of Veterinary Studies, UK

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