Sciurus niger | Eastern Fox squirrel | Iora sionnaigh oirthearach



Conservation status

Least concern

Legal status

Regulated invasive species of Union concern under the European Regulation on the prevention and management of the introduction and spread of invasive alien species [1143/2014].

Introduction pathways - 1

Escape from Confinement

Introduction pathways subclass - 1

Pet/aquarium species

Introduction pathways - 2


Introduction pathways subclass - 2

Natural dispersal across borders of invasive aliens

NAPRA Ireland risk assessed


Species Biology


A relatively large, long-lived arboreal squirrel with a total length of 45-70cm. Colour is variable but generally body is reddish-brown, grey or black agouti. Chest and abdomen are white, cinnamon or red. No sexual dimorphism. Unique to Sciurus niger is an accumulation of uroporphyrin in tissues, teeth and bones making bones pink rather than white (Koprowski, 1994).


Feeds mainly on tree seeds, nuts, flowers and buds but a very small proportion of its diet may be made up of insects and birds eggs (Koprowski, 1994). Most active around sunrise and sunset. Moults twice annually and can live up to 15 years (Koprowski, 1994). Like many squirrel species it is a scatterhoarder, burying any surplus nuts it finds for consumption later (Koprowski, 2011). Has many different calls but most commonly heard is a sharp bark (Koprowski, 1994). Has been reported to damage phone and electricity wires and gardens. May be a threat to the native Red squirrel (Sciurus vulgaris) in Ireland and other European countries by competing for territory and valuable resources. Strips bark from trees only during times of food shortage (Baiwy et al., 2015).


Both deciduous and mixed forest with an open understorey as well as wooded riparian zones (Koprowski, 2011).


Breeding can occur at any time of the year (Koprowski, 1994). Females can generally reproduce from 16 months of age (Koprowski, 1994). Each female mates with several different males (Koprowski, 2011) and produces 2-3 young. Young are born hairless, blind and deaf. Weaned at 12 weeks old (Koprowski, 1994). Nests are either made of sticks and leaves or a tree hollow is used (Koprowski, 1994).

Pathway and vector description

Import through the pet trade (European Commission, 2017). Can readily be purchased online (UNEP-WCMC, 2010). They have not yet escaped into the wild in Europe (European Commission, 2017).

Mechanism of impact

Competition, Other

Management approach

Have locally been trapped, poisoned or shot but there has been no concerted effort to eradicate S. Niger from its introduced range. Dagnall et al. (1998 in Koprowski, 2011) suggest control may be achieved by managing forests in such a way to reduce squirrel numbers, or sterilising with immuno-contraceptive vaccines.

Broad environment


Species group


Native region

North America

Similar species

Sciurus carolinensis & S. vulgaris. 
S. niger  is by far the largest at 45-70cm body length, coat is reddish-brown, gray or agouti, underside may be white, cinnamon or red. Spends a large proportion of its time on the ground.
S. carolinensis 25-30cm body length, coat is predominantly gray with a white underside. 
S. vulgaris 19-23cm body length, coat is predominantly red with white-cream underside. Has distinctive ear tufts. Spends little time on the ground.


World distribution(GBIF)

Currently expanding its range westwards in the USA (Koprowski, 2011).

Native distribution

Canada, Mexico, USA

Temporal change

Records submitted to Data Centre in 2021

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How can you help

Do not purchase as a pet.

Report any sightings to the National Biodiversity Data Centre.



Baiwy, E., Schockert, V. & Branquart, E. (2015) Risk analysis of the Fox squirrel, Sciurus niger, Risk analysis report of non-native organisms in Belgium. Cellule interdépartementale sur les Espèces invasives (CiEi), DGO3, SPW / Editions, updated version, 34 pages Site accessed 26 Septmber 2017.

Dagnall J; Gurnell J; Pepper H, 1998. Barkstripping damage by gray squirrels in state forests of the United Kingdom: a review. In: Ecology and evolutionary biology of tree squirrels [ed. by Steele, M. A. \Merritt, J. F. \Zegers, D. A.]. Martinsville, USA: Virginia Museum of Natural History, 249-261. [Special Publication,Virginia Museum of Natural History.].

European Commission. (2017). Invasive Alien Species of Union Concern. European Union, Luxembourg.

Koprowski, JL (2011) Invasive Species Compendium. Datasheet report for Sciurus niger (Fox squirrel). Wallingford, UK: CAB International. Site accessed 26 September 2017.

Koprowski, JL (1994) Callosciurus erythraeus (Rodentia: Sciuridae), Mammalian Species, (479), Pp 1-9, Site accessed 26 September 2017.

UNEP-WCMC (2010) Review of Callosciurus erythraeus and Sciurus niger. UNEP-WCMC, Cambridge. Site accessed 26 September 2017.

Additional comments

There are 10 different subspecies of Sciurus niger: S. n. avicennia, S. n. bachmani , S. n. cinereus , S. n. limitis, S. n. ludovicianus , S. n. niger , S. n. rufiventer , S. n. shermani , S. n. subauratus , S. n. vulpinus