{{Short description|Species of mammal}}{{Use mdy dates|date=November 2025}} {{Multiple issues|{{Cleanup rewrite|date=October 2025}} {{Technical|Description section|date=October 2025}}}} {{Speciesbox | name = Nicobar treeshrew | image = Nicobar Treeshrew (Tupaia nicobarica nicobarica).jpg | status = EN | status_system = IUCN3.1 | status_ref = <ref name=iucn>{{cite iucn |title=''Tupaia nicobarica'' |name-list-style=amp |author1=Laginha Pinto Correia, D. |author2=Kennerley, R. |article-number=e.T22454A115166757 |year=2016 |errata=2017 |access-date=26 January 2022}}</ref> | status2 = CITES_A2 | status2_system = CITES | status2_ref = <ref name=iucn/> | genus = Tupaia | species = nicobarica<ref name=msw3/> | authority = (Zelebor, 1868) | synonyms = | range_map = Nicobar Treeshrew area.png | range_map_caption = Nicobar treeshrew range }}
The '''Nicobar treeshrew''' ('''''Tupaia nicobarica''''') is a species of small, non-volant<ref name=":0">{{Cite journal |last1=Kundu |first1=Shantanu |last2=Tyagi |first2=Kaomud |last3=Kamalakannan |first3=Manokaran |last4=Kumar |first4=Vikas |last5=Venkatraman |first5=Chinnadurai |last6=Sivaperuman |first6=Chandrakasan |last7=Chandra |first7=Kailash |date=2020-04-02 |title=Molecular investigation of non-volant endemic mammals through mitochondrial cytochrome b gene from Andaman and Nicobar archipelago |url=https://doi.org/10.1080/23802359.2020.1738282 |journal=Mitochondrial DNA Part B |volume=5 |issue=2 |pages=1447–1452 |doi=10.1080/23802359.2020.1738282|doi-access=free }}</ref> mammal.<ref name=msw3>{{MSW3 Helgen |id=11900037 |page=108 |heading=''Tupaia nicobarica''}}</ref> It is endemic to the Nicobar Islands of the Andaman Sea, India.<ref name=":1">{{Cite journal |last1=Kundu |first1=Shantanu |last2=Pakrashi |first2=Avas |last3=Kamalakannan |first3=Manokaran |last4=Singha |first4=Devkant |last5=Tyagi |first5=Kaomud |last6=Banerjee |first6=Dhriti |last7=Venkatraman |first7=Chinnadurai |last8=Kumar |first8=Vikas |date=2022-01-18 |title=Complete mitogenome of the endangered and endemic Nicobar treeshrew (Tupaia nicobarica) and comparison with other Scandentians |journal=Scientific Reports |language=en |volume=12 |issue=1 |pages=877 |doi=10.1038/s41598-022-04907-7 |issn=2045-2322 |pmc=8766473 |pmid=35042947 |bibcode=2022NatSR..12..877K }}</ref> where it inhabits the islands' rain forests. Based on geographical distribution, there are two subspecies identified: ''T. nicobarica nicobarica'' from the Great Nicobar Island and ''T. nicobarica surda'' from the Little Nicobar Island.<ref>{{Citation |last1=Sivaperuman |first1=C. |title=Mammals of Andaman and Nicobar Islands |date=2018 |work=Indian Hotspots: Vertebrate Faunal Diversity, Conservation and Management Volume 2 |pages=151–164 |editor-last=Sivaperuman |editor-first=Chandrakasan |url=https://doi.org/10.1007/978-981-10-6983-3_8 |access-date=2025-10-30 |place=Singapore |publisher=Springer |language=en |doi=10.1007/978-981-10-6983-3_8 |isbn=978-981-10-6983-3 |last2=Gokulakrishnan |first2=G. |last3=Parthipan |first3=P. |editor2-last=Venkataraman |editor2-first=Krishnamoorthy|url-access=subscription }}</ref>
It is threatened by habitat loss,<ref name="iucn" /> anthropogenic activities, forest fragmentation, tsunami events, and predation by other animals.<ref>{{Cite journal |last1=Srinivasulu |first1=C. |last2=Srinivasulu |first2=Bhargavi |last3=Rajesh |first3=A. |last4=Rao |first4=C.A.N. |last5=Nagulu |first5=V. |date=2004-05-21 |title=Fauna of Protected Areas - 8: Non-volant small mammals of Kasu Brahmananda Reddy National Park, Andhra Pradesh |url=https://doi.org/10.11609/jott.zpj.1088.1495-7 |journal=Zoos' Print Journal |volume=19 |issue=6 |pages=1495–1497 |doi=10.11609/jott.zpj.1088.1495-7 |issn=0973-2535}}</ref> and is classified as an Endangered species in the IUCN Red List of Threatened Species.<ref name="iucn" /> Despite the listing, it is commonly found in its appropriate habitats.<ref>{{cite journal |last1=Oommen |first1=MA |last2=Shanker |first2=Kartik |year=2008 |title=Ecology and Behaviour of an endemic treeshrew ''Tupaia nicobarica'' Zelebor 1869 on Great Nicobar Island, India |journal=Journal of the Bombay Natural History Society |volume=105 |issue=1 |pages=55–63 |url=https://www.biodiversitylibrary.org/part/154629}}</ref>
The Nicobar treeshrew was first described by Johann Zelebor in 1868.<ref>Zelebor, J. (1868). [http://digital.slub-dresden.de/werkansicht/cache.off?id=5363&tx_dlf%5Bid%5D=32604&tx_dlf%5Bpage%5D=23 ''Cladobates Nicobaricus'']. In: Reise der österreichischen Fregatte Novara um die Erde. Zoologischer Theil, Band 1 Säugethiere. Wien: Kaiserliche Akademie der Wissenschaften. Pp. 17–19.</ref>
== Habitat == The Nicobar treeshrew only occupies the Indian Islands of Great Nicobar and Little Nicobar and can be found on the highest points of these two islands, {{cvt|640|m}} above sea level.<ref>{{cite journal |last1=Narasimmarajan |first1=K. |year=2014 |title=Recent photographic observation of Nicobar Treeshrew ''Tupaia nicobarica'' (Zelebor, 1869) on Great Nicobar Island |journal=Small Mammal Mail |volume=5 |issue=2 |pages=2–3 |url=https://www.researchgate.net/publication/264628503}}</ref> It lives in different forest types such as scrub jungle, moist deciduous forests, and montane sholas.<ref name=":1" />
== Description == Morphologically, the Nicobar treeshrew resembles the squirrel and the mongoose,<ref name=":0" /> with an elongated snout, hairless and moist nasal pad, and lack of whiskers on their cheeks.<ref name=":2" />
It possesses distinct craniomandibular and body characteristics that differentiate it from other South Asian treeshrews. Its lambdoid–premaxillary length averages 53.7 ± 0.79 mm (range 52.4–54.9 mm),<ref name=":2">{{Cite journal |last1=Kamalakannan |first1=Manokaran |last2=Thakur |first2=Mukesh |last3=Marimuthu |first3=Nithyanandam |last4=Pramanik |first4=Subhojit |last5=Banerjee |first5=Dhriti |date=2025 |title=Museum Specimens Reveal the Taxonomic Distinctions Among South Asian Treeshrews |journal=Ecology and Evolution |language=en |volume=15 |issue=4 |article-number=e71202 |doi=10.1002/ece3.71202 |issn=2045-7758 |pmc=12017894 |pmid=40270801 |bibcode=2025EcoEv..1569.R2K }}</ref> while the mandibular condylo–incisive length measures 39.7 ± 0.46 mm (range 39.1–40.3 mm).<ref name=":2" /> The orbit to interorbital breadth is 0.90 ± 0.09 mm (range 0.80–1.09 mm),<ref name=":2" /> with the orbits slightly curved in structure. The mandibular coronoid breadth is notably large (3.47 ± 0.26 mm, range 3.02–3.85 mm),<ref name=":2" /> demonstrating the species' robust jaw morphology. Body measurements show relatively long head–body lengths of 193.3 ± 12.99 mm (range 180–224 mm)<ref name=":2" /> and tail lengths of 226.1 ± 10.02 mm (range 210.5–240 mm).<ref name=":2" /> The species displays a dorsal bicolor pelage and an average body weight of about 170 g,<ref name=":2" /> which helps with its identification as a comparatively large treeshrew among other treeshrews species.
== Phylogeny == Phylogenetic analyses indicate that ''T. nicobarica'' diverged from a common ancestor of the ''Tupaiidae'' lineage approximately 12–19 million years ago, during the Miocene.<ref name=":1" /> This suggests a long period of isolation in the Nicobar Islands. Further genetic studies based on 16S rRNA genes (1667 bp) showed significant genetic variability between ''T. nicobarica'' and other ''Tupaia'' species, which supports the fact that it is endemic to the Nicobar islands. It also demonstrated that ''T. nicobarica'' is related to ''T. minor'', ''T. tana'', ''T. splendidula'', and ''T. montana'', present in Thailand, Peninsular and East Malaysia, Brunei Darussalam, Sumatra, and Indonesia, including ''T. javanica'', located in Sumatra and Java islands, as a sister specie to ''T. nicobarica''.<ref name=":1" />
== Ecology and behavior == The Nicobar treeshrew lives primarily in trees and ground, but it can also exhibit scansorial habits,<ref name=":3">{{Cite journal |last1=Oommen |first1=Meera Anna |last2=Shanker |first2=Kartik |date=2010-06-23 |title=Shrewd alliances: mixed foraging associations between treeshrews, greater racket-tailed drongos and sparrowhawks on Great Nicobar Island, India |journal=Biology Letters |language=en |volume=6 |issue=3 |pages=304–307 |doi=10.1098/rsbl.2009.0945 |issn=1744-9561 |pmc=2880059 |pmid=20007167}}</ref> which demonstrates diversity in its behavior. The Nicobar treeshrew is insectivorous and frugivorous,<ref name=":2" /> feeding mainly on insects and fruits. It also contributes to seed dispersal in tropical forests,<ref name=":0" /> playing an important ecological role in renewal of forest ecosystems. ''T. nicobarica'' has a small social structure. It is most often observed as solitary individuals or breeding pairs that forage and rest together. In its natural habitat, the species is known to be preyed upon by sparrowhawks (''Accipiter'' spp.).<ref name=":3" />
==References== {{Reflist}}
==External links== * [https://web.archive.org/web/20100916032900/http://www.arkive.org/nicobar-treeshrew/tupaia-nicobarica/ Nicobar treeshrew (Tupaia nicobarica)] * [https://web.archive.org/web/20110609145322/http://ces.iisc.ernet.in/kartik/ks_treeshrew.html Nicobar treeshrew] * [https://web.archive.org/web/20110609145345/http://ces.iisc.ernet.in/kartik/Tupaia%202.jpg Nicobar treeshrew]
{{Scandentia}}
{{Taxonbar|from=Q1338043}} {{Authority control}} Category:Treeshrews Category:Mammals of India Category:Mammals described in 1868 Category:Taxonomy articles created by Polbot