Recognising types of mammal damage to trees and woodland

Every stage of tree growth may be attacked by one or more species of mammal.  Often a species may cause damage at several growth stages. Most mammal damage to trees is from either:

  • Browsing - feeding on buds, shoots and foliage
  • Bark stripping from main stems or branches - gnawing or rubbing.

When trying to identify the cause of damage, the most important things to look for are:

  • Form of damage (i.e. browsing, gnawing or rubbing)
  • Height of damage
  • Time of year when damage occurred
  • Presence and size of teeth marks
  • Signs of animal presence and abundance - droppings, footprints, runs, scrapes or burrows.

Points to note:

  • Lack of teeth in front upper jaw of all deer species produces ragged edge on damaged twigs
  • The teeth of rabbits and hares produce a sharp knife like cut. Muntjac may bite partly through thin tall stems and pull them down to eat
  • Sheep and deer browsing damage is often very similar in form but sheep tend to leave wool evidence
  • Fraying is a rubbing injury caused when male deer rub new antlers to remove ‘velvet’ or to mark territories.

The following three tables show the main characteristics of damage by:

A: Wild deer
B: Other wild mammals including rabbits, hares, squirrels, mice, voles, edible dormice, moles and badgers
C: Domestic livestock

Brackets in the ‘age of trees’ column denote damage is uncommon.

Table A: Wild deer

Species Age of trees affected Typical signs of damage to trees Comments; damage to other parts of woodland etc.
Red deer
  • Establishment
  • Thicket
  • Pole stage
  • Mature
  • Browse seedlings to thicket stage
  • Fraying and rubbing on bark up to 1.8m
  • Damage to poor fences
  • Severe damage to herb layer
Sika deer
  • Establishment
  • Thicket
  • Pole stage
  • Mature
  • Browse seedlings to thicket stage
  • Scoring of pole stage trunks
  • Fraying and rubbing on bark up to 1.8m
 
Fallow deer
  • Establishment
  • Thicket
  • Pole stage
  • (Mature)
  • Browse seedlings to thicket stage
  • Fraying bark up to 1.5m
  • May pull up recently planted trees
  • Severe damage to herb layer
Roe deer
  • Establishment
  • Thicket
  • Pole stage
  • Mature
  • Browse seedlings to thicket stage
  • Fraying bark up to 1.2m
  • Severe damage to herb layer
Muntjac deer
  • Establishment
  • Thicket
  • Browse seedlings to thicket stage
  • Fraying bark up to 1m
  • May partly bite through taller stems and pull down to browse
  • Capable of severe damage to herb layer

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Table B: Other wild mammals

Species Age of trees affected Typical signs of damage to trees Comments; damage to other parts of woodland etc.
Voles (bank & field)
  • Seedling
  • Establishment
  • Eating seeds, seedlings, root cutting of young planted stock
  • Ringbarking up to 10cm
  • Teethmarks only 2mm wide
  • Bank vole will climb saplings and eat bark around base of branch
  • Typical runways in grass with dropping and cut grass piles evident
  • Nests in tree shelters
Mice (wood, yellow-necked & house)
  • Seedling
  • Establishment
  • Eating seeds, seedlings,
  • Seed stores
  • Nests in tree shelters or under mulch mats
Grey squirrel
  • Seedling
  • Thicket
  • Pole stage
  • Mature
  • Stripping bark anywhere on stem or branches of pole stage and mature trees
  • Bark stripping at bottom 50cm of stem may be confused with rabbit damage
  • Eating larger seeds
  • Predation of bird nests
Edible dormouse
  • Pole stage
  • Mature
  • Spiral bark stripping at branch bases
  • Very restricted range
  • Hibernates below ground
  • Compete for tree holes
Rabbit
  • Establishment
  • Seedling
  • Thicket
  • Pole stage
  • (Mature)
  • Cutting stems of planted saplings
  • Ringbarking bottom 50cm of stem
  • Burrows assist windblow
  • Sharp angled knife-like cuts on end of small stems or branches
  • Removed portion often eaten
  • Most vegetation in area around burrow often grazed very low
Hare (mountain & brown)
  • Establishment
  • Thicket
  • Often sporadic but widespread
  • May eat along a row of young trees
  • Damage up to 70cm
 
Badger
  • Pole stage
  • Mature
  • Setts under roots
  • Limited bark damage
  • Create holes under fences for other pests to gain entry
Mole
  • Seedling
  • Establishment
  • Tunnelling may cause desiccation of seedlings and transplant roots
  • Soil heaps may bury young plants
  • Assists drainage of gley soils

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Table C: Domestic livestock

Species Age of trees affected Tree and other collateral damage
Sheep
  • Establishment
  • Thicket
  • (Pole stage)
  • Removal of ground vegetation
  • Browsing and bark stripping
  • Newly planted trees may be pulled out
Goat
  • Establishment
  • Thicket
  • Pole stage
  • Removal of ground vegetation
  • Browsing and bark stripping
  • Newly planted trees may be pulled out
Cattle
  • Establishment
  • Thicket
  • Pole stage
  • Removal of ground vegetation and newly planted trees or natural regeneration
  • Treading impacts may be detrimental to roots or beneficial by providing nutrient and germination patches
  • Coarse browsing of foliage to 1.5 m
  • Newly planted trees may be pulled out
Pigs & feral boar
  • Seedling
  • Establishment
  • Thicket
  • Pole stage
  • (Mature)
  • Removal of large seeds, ground vegetation and natural regeneration
  • Browsing and root damage by grubbing
  • Digging rabbit burrows, holes created under fences
  • Rubbing on trunks
Ponies
  • Establishment
  • Thicket
  • (Pole stage)
  • Newly planted trees may be pulled out
  • Browsing to 2 metres
  • Bark stripping with characteristic diagonal teeth marks from both jaws
  • Grazing shrubs and ground flora

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What's of interest

Further reading
Several Forestry Commission publications covering mammal management in more detail. Some are available for downloading.

Related pages