Management of grey squirrels

 

Summary

Since their introduction into Britain between 1876 and the 1920’s, grey squirrels have spread rapidly, gradually displacing the native red squirrel in most of England and Wales, and in central and south-east Scotland. Grey squirrels are extremely destructive in woodlands, stripping bark from the main stem and branches of trees. Increasingly, wider impacts of grey squirrels are being recognised as of potential major significance to woodland conservation, biodiversity and sustainability. The aims of this research programme include:

• Investigate the impact of grey squirrels on woodland biodiversity & identify efficient control strategies
• Develop cost effective methods of managing impacts on timber production
• Develop a decision-support system to provide guidance to woodland managers on targeting grey squirrel control to support sustainable forest management
• Promote and support best practice management for the control of grey squirrels and their impacts.

Research objectives

Red and grey squirrel distribution from 1998 data
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For a map showing the most up to date distribution see
National Biodiversity Network Gateway.

• Develop methods of predicting grey squirrel damage to improve the targeting of control by gaining a better understanding of the relationship between squirrel population dynamics, habitat structure and bark stripping damage
• Assess impacts of the introduced grey squirrel on sustainable woodland management
• Investigate competition with native mammals such as the red squirrel and common dormouse and predation on woodland birds 
• Investigate indirect impacts on woodland structure through seed predation and bark stripping influences on tree growth and stand structure
• Investigate novel and develop improved methods of population control, including reviewing the potential use of attractants
• Monitor developments (worldwide) in the use of immuno-contraceptives for mammal population control, and consider their potential application to grey squirrel control (see reproductive inhibition in grey squirrels)
• Determine the effects of grey squirrel damage on timber quality and develop cost benefit analysis for control of damage in broadleaf and conifer woodlands
• Investigate alternative methods of damage limitation such as stand management, and the development of physical and chemical deterrents
• Provide practical advice to the forest industry and the general public and promote best practice by supporting training seminars and workshops on grey squirrel control for woodland owners and managers.

Funders and  partners

This research is funded by the Forestry Commission Grey squirrel management programme. This includes an annual summary of the research.

Bark stripping damage to trees

Grey squirrel damage to 18-year old planted oak in a farm woodland planting scheme
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Grey squirrel bark-stripping to main stem of sycamore
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Fresh grey squirrel basal damage to beech (bark strips visible)
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Windsnap to 40-year old Norway spruce following grey squirrel bark-stripping damage
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Damage varies across sites and between years and is difficult to predict. Thin barked species such as sycamore, beech, oak, sweet chestnut, pine, larch and Norway spruce are most at risk with trees aged between 10 and 40 years being most vulnerable. Bark stripping damage reduces timber quality through staining (due to fungal infection) and structural defects and ultimately reduces timber value and yield. Weakened stems may break and trees that are ring-barked will die from that point up.

Further reading

Forestry Commission and other publications covering the management of grey squirrels. Some are available for downloading.

Status

The programme will be reviewed in 2005/06. 

Contacts

Programme Manager

Brenda Mayle
Forest Research
Alice Holt Lodge
Farnham
Surrey GU10 4LH
 
Tel: +44 (0)1420 22255
Tel direct: +44 (0)1420 526236
Fax: +44 (0)1420 520180
Email: brenda.mayle@forestry.gsi.gov.uk

For general enquiries and advice on grey squirrel control 

Mark Ferryman  
Forest Research
Alice Holt Lodge
Farnham
Surrey GU10 4LH
 
Tel: +44 (0)1420 22255
Tel direct: +44 (0)1420 526164
Fax: +44 (0)1420 520180
Email: mark.ferryman@forestry.gsi.gov.uk