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 Will damage trees up to 100cm diameter	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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