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Understanding why grey squirrels (Sciurus carolinensis) bark strip in British woodlands: a systematic map

Understanding why grey squirrels (Sciurus carolinensis) bark strip in British woodlands: a systematic map
Understanding why grey squirrels (Sciurus carolinensis) bark strip in British woodlands: a systematic map

Background: the damage to trees caused by grey squirrels in Britain undermines the UK Government's ambitious afforestation targets for expanding woodland area to sequester carbon. The motivations of grey squirrel bark stripping are poorly understood, hindering the development of non-lethal management options that target bark stripping. 

Aim: we provide a broad synthesis of the literature on the bark-stripping behaviour of squirrel species with the specific goal of identifying methods to understand and mitigate the bark-stripping behaviour of grey squirrels in Britain. 

Methods: we searched for articles that described or investigated the bark-stripping behaviour of squirrel species. Literature searches were conducted in English, Spanish, Simplified Chinese and Traditional Chinese using relevant platforms for literature-search databases. Information extracted from the articles included coding variables defined by study meta-data, study design and contextual variables for bark-stripping behaviour.

Results: we identified 188 relevant articles on sciurid bark-stripping behaviour in North America, South America, Europe, Asia and Africa. Most studies were observational (65%), identifying important tree and stand characteristics associated with tree susceptibility to damage. Experimental studies (15%) largely aimed to identify methods to prevent damage caused by squirrels, with none finding an effective, practical and humane solution for preventing or reducing damage. Evidence for the causes of bark-stripping behaviours remains sparse, particularly for species that cause significant economic damage. 

Conclusion: future research should prioritise experimental designs and interdisciplinary collaborations aiming to establish causal understanding. For the grey squirrel, we propose multiple hypotheses that warrant further investigation, including nutritional deficiencies, self-medication, scent-marking and agonistic behaviours.

Sciuridae, bark stripping, grey squirrel, systematic map, tree health
Ash, Alexandra K.
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Spake, Rebecca
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Zhao, Yanjie
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Piña‐Covarrubias, Evelyn
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Gill, Robin M.A.
87097cb9-7215-42c1-be0f-e53b4081c954
Nichols, Christopher P.
540573ba-1ff5-413e-9652-c43bef6f637f
Doncaster, C. Patrick
0eff2f42-fa0a-4e35-b6ac-475ad3482047
Ash, Alexandra K.
0d0bd226-5c32-4f2d-b307-9dec30158073
Spake, Rebecca
1cda8ad0-2ab2-45d9-a844-ec3d8be2786a
Zhao, Yanjie
84baf146-1a1f-46a7-9c03-66e5dfb68401
Piña‐Covarrubias, Evelyn
a3202474-20c4-4a8c-b34d-713d8e060f0f
Gill, Robin M.A.
87097cb9-7215-42c1-be0f-e53b4081c954
Nichols, Christopher P.
540573ba-1ff5-413e-9652-c43bef6f637f
Doncaster, C. Patrick
0eff2f42-fa0a-4e35-b6ac-475ad3482047

Ash, Alexandra K., Spake, Rebecca, Zhao, Yanjie, Piña‐Covarrubias, Evelyn, Gill, Robin M.A., Nichols, Christopher P. and Doncaster, C. Patrick (2026) Understanding why grey squirrels (Sciurus carolinensis) bark strip in British woodlands: a systematic map. Mammal Review, 56 (1), [e70027]. (doi:10.1111/mam.70027).

Record type: Article

Abstract

Background: the damage to trees caused by grey squirrels in Britain undermines the UK Government's ambitious afforestation targets for expanding woodland area to sequester carbon. The motivations of grey squirrel bark stripping are poorly understood, hindering the development of non-lethal management options that target bark stripping. 

Aim: we provide a broad synthesis of the literature on the bark-stripping behaviour of squirrel species with the specific goal of identifying methods to understand and mitigate the bark-stripping behaviour of grey squirrels in Britain. 

Methods: we searched for articles that described or investigated the bark-stripping behaviour of squirrel species. Literature searches were conducted in English, Spanish, Simplified Chinese and Traditional Chinese using relevant platforms for literature-search databases. Information extracted from the articles included coding variables defined by study meta-data, study design and contextual variables for bark-stripping behaviour.

Results: we identified 188 relevant articles on sciurid bark-stripping behaviour in North America, South America, Europe, Asia and Africa. Most studies were observational (65%), identifying important tree and stand characteristics associated with tree susceptibility to damage. Experimental studies (15%) largely aimed to identify methods to prevent damage caused by squirrels, with none finding an effective, practical and humane solution for preventing or reducing damage. Evidence for the causes of bark-stripping behaviours remains sparse, particularly for species that cause significant economic damage. 

Conclusion: future research should prioritise experimental designs and interdisciplinary collaborations aiming to establish causal understanding. For the grey squirrel, we propose multiple hypotheses that warrant further investigation, including nutritional deficiencies, self-medication, scent-marking and agonistic behaviours.

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Mammal Review - 2026 - Ash - Understanding Why Grey Squirrels Sciurus carolinensis Bark Strip in British Woodlands A - Version of Record
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More information

Accepted/In Press date: 24 February 2026
e-pub ahead of print date: 18 March 2026
Published date: 18 March 2026
Keywords: Sciuridae, bark stripping, grey squirrel, systematic map, tree health

Identifiers

Local EPrints ID: 510969
URI: http://eprints.soton.ac.uk/id/eprint/510969
PURE UUID: f31b8562-7be0-4c74-a9ff-e8d1a1617a36
ORCID for Alexandra K. Ash: ORCID iD orcid.org/0000-0002-2647-7945
ORCID for Rebecca Spake: ORCID iD orcid.org/0000-0003-4671-2225
ORCID for Yanjie Zhao: ORCID iD orcid.org/0000-0001-9307-8138
ORCID for Evelyn Piña‐Covarrubias: ORCID iD orcid.org/0000-0002-3564-7467
ORCID for C. Patrick Doncaster: ORCID iD orcid.org/0000-0001-9406-0693

Catalogue record

Date deposited: 28 Apr 2026 16:42
Last modified: 29 Apr 2026 02:05

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Contributors

Author: Alexandra K. Ash ORCID iD
Author: Rebecca Spake ORCID iD
Author: Yanjie Zhao ORCID iD
Author: Evelyn Piña‐Covarrubias ORCID iD
Author: Robin M.A. Gill
Author: Christopher P. Nichols

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