The nineteenth century saw the introduction of many ‘exotic’ or non native species.  Some of these introductions have proved to be invasive, for example the Himalayan balsam.  Invasions have also included animals. For example, muntjac, parakeets and grey squirrels.  More recently, there have been many sightings of wallabies. Their presence is thought to be due to escapees from wildlife parks, zoos and possibly private collections. It has been suggested that some were released during the WW2 as people were unable to look after them.  On the Isle of Man, there is a thriving population of red necked wallabies, which dates back to the 1960’s.  A recent survey (2023 & 2024) using thermal imaging and drones estimates the population to be around one thousand animals, possibly more.  The grassy and woodland habitats are not dissimilar to those in Tasmania, though the climate in the Isle of Man is somewhat cooler and wetter.  Here, there are no predators and they seem to have adapted well to the somewhat cooler conditions. They feed on heather, bracken, bilberries and grasses.  The local wildlife trust is concerned that the animals may be having a detrimental effect not only on the native vegetation but also the local fauna - such as ground nesting birds.  On the plus side, there are those who think their presence helps to support the local tourism industry. Beyond the Isle of Man, there have been many sightings of wallabies across the U.K, ranging from Cornwall to Scotland.  Sightings are more common in the South.  In some areas sightings of wallabies are no longer reported as the animals are ‘common place’. The Chilterns being a possible hot spot for sightings.  However, at present it seems that there is little evidence for self sustaining populations though this might change as our climate becomes milder.  There was a small population in the Peak District but it has since died out, possibly due to a harsh winter in 2010.  This population arose from the introduction of five wallabies by a local landowner, Henry Brocklehurst,  the  wallabies formed part of his private zoo at Swythamley. Featured image : thanks to Sandid on PIxabay  

 The red squirrel is a native species, it has been present in the British Isles since the retreat of the glaciers of the last ice age -so around for some 10,000 years.  The grey squirrel on the other hand has only been here since the mid nineteenth century, when it was introduced from America.  Though relatively small numbers were introduced at stately homes, it did incredibly well and they spread out from their original sites, colonising woodlands and spreading across the country.  As the grey squirrel spread so the red squirrel retreated and its numbers declined. Recent population estimates suggest that the grey squirrel population may now be as high as three million, whereas the red squirrel numbers are probably less than 300,000. The grey squirrel is to be regarded as a pest.  Why ? (a).   They strip bark from trees.   This is the main type of damage type of damage. The squirrels remove  bark to access the sap tissues underneath. [caption id="attachment_42793" align="aligncenter" width="675"] Squirrel damage[/caption] (b).   They cause the death of trees.  The damage to the bark and the underlying tissue can affect the flow of water and nutrients from soil to leaves.  It can also allow for the entry of pathogens (parasitic bacteria and fungi). (c).   Their activities have an impact on the quality of timber that can be harvested. (d).   They are associated with biodiversity loss, not only do they complete with and displace the native red squirrel, their presence can affect other woodland species such as songbirds (eat their eggs) and dormice. (e).   Grey squirrels pass on the squirrel pox virus to red squirrels.  Once infected the red squirrels tend to die of dehydration and starvation. [(f).   The grey squirrels that visit my garden dig up bulbs, like crocus, tulips and hyacinths.  They also make raids on soft fruits.] [caption id="attachment_42794" align="aligncenter" width="675"] Older damage by squirrels[/caption] There are measures to stop or limit grey squirrels from breeding.   One ‘extreme’ measure is shooting or trapping followed by euthanasia.  Another measure is the introduction of Pine Martens, they seem to control the numbers of grey squirrels whereas red squirrels have co-existed with Pine Martens in areas like north Scotland for many years.   However, the Governments Animal and Plant agency is developing a contraceptive.  This is a vaccine based product which causes the squirrel’s immune system to render both males and females infertile.   The vaccine induces the formation of antibodies against the animals own reproductive hormones. The idea is to fed it to the grey squirrels through feeding hoppers that grey squirrels can access but not red squirrels or other animals. The bait will need to be palatable and attractive to the squirrels. Should this prove successful, it will be a non-lethal way of reducing the numbers of the grey squirrel without shooting or trapping.   For detailed information on the squirrel contraceptive project, visit https://aphascience.blog.gov.uk/2024/09/30/reducing-grey-squirrel-overpopulation/ Similarly, lots of information on squirrel damage here : https://www.observatree.org.uk/media/1425/identifying-squirrel-damage.pdf  

JAcross Europe, the red squirrel is recognised as an endangered species.  The U.K populations are at risk due due to :- Habitat loss Competition with Grey Squirrels The effects of the squirrel pox virus The last two are a result of the introduction of the grey squirrel from America in the 19th century. Red squirrels are at home in all types of woodland and may even be seen in parks and gardens, but they 'like' mixed conifer forests best.  Scotland is home to many of the U.K's red squirrels. The number of squirrels is quite small – estimates of their number vary, perhaps there are less than 300,000* across the whole of Britain.   The status of red squirrel populations is a matter of considerable interest. [caption id="attachment_42416" align="alignleft" width="300"] Screenshot[/caption]  In 2014, it was noticed that some members of the Scottish red squirrel populations had abnormal growths on their ears, snout and limbs. Further investigations found that the squirrels were suffering from leprosy.  Leprosy  is a bacterial infection,  caused by two different species of mycobacteria: Mycobacterium leprae and Mycobacterium lepromatosis.   The two types of  bacteria have slightly different distributions in the squirrel populations of the U.K.  Whilst leprosy in squirrels was first reported in 2014,  it is likely that the disease has been around in squirrel populations for much, much longer, probably hundreds of years. Profesor Verena Schünemann,  Christian Urban et al have studied bacterial DNA extracted from human skeletons, dating from 400 CE to 1400 CE with deformities associated with leprosy.   They 'reconstructed' the genetic makeup of mediaeval forms of the bacterium.  Leprosy was not uncommon across Europe in mediaeval times - indeed up to the sixteenth century.   Disease, in its many forms , was a common part of life -  dysentery, diphtheria, typhoid, smallpox, and plague meant that life expectancy was limited. The last indigenous case of leprosy in the UK dates back to 1798.  In humans, leprosy causes muscle and nerve damage, which lead to deformity, blindness and disability.   Interestingly, research by Dr. Sarah Inskip has revealed that a pre-Norman skull [found in Hoxne in Suffolk] had a leprosy strain related to a form known to affect squirrels.  The same strain has also been found in medieval scandinavian skeletons.  It is possible that the  trade in squirrel pelts (and meat) could have contributed to the spread of the disease. Strong trade connections with Denmark and Sweden were in full flow in the medieval period.  Squirrel fur was also used as a lining for fine clothes and squirrels were kept as pets by some. The historical spread of leprosy is not fully understood.  The disease may have passed from squirrels to humans or vice versa in historical times.  Further study of the microbes that cause this disease (and that in squirrels) will help determine how the disease is acquired and transmitted.    The risk to human health is low. (Even so, good hygiene should be followed during any contact with wild animals). Professor Anna Meredith  (University of Edinburgh) is researching into this disease in squirrels.   Further reading / articles: https://www.newscientist.com/article/mg14819991-200-virus-blamed-on-invading-squirrels/ https://www.science.org/doi/10.1126/science.aah3783 https://www.theguardian.com/science/2017/oct/25/medieval-love-of-squirrel-fur-may-have-helped-spread-leprosy-study-reveals https://www.sciencedaily.com/releases/2017/10/171025103109.htm

Much has been written about the explosion of the UK deer population in recent times, and the damage to woodlands through their browsing activities.  However, the grey squirrelis associated with tree damage.  The grey squirrel is not just the 'cheeky chap' who steals the bird food in the garden, it is a serious pest.    The grey squirrel is a non-native species.  It was introduced in the 19th century.  The squirrels have spread across the country and have displaced the native red squirrel from many areas (either through competition or disease).  The grey squirrel's bark stripping activity now poses a threat to the sustainable management of woodlands. Gnawing of the bark means that they can get to the sweet, sap filled tissue (phloem) just beneath the bark. This tissue is responsible for the movement of sugars and other organic molecules around the plant (known as translocation). If the gnawing extends around the stem then the tree is ‘ringed’ [i.e a complete circle of bark and underlying tissue is removed]  then the tree us likely to die.  The squirrels tend to take bark from the main stem (and branches). The bark stripping may : Lead to the loss of particular tree species (for example, beech) Lead to the loss of insect / spider and fungal species associated with the loss of tree species, i.e. a loss of biodiversity allow fungal infection of the tree Reduce carbon capture Reduce the economic value of timber Act as a disincentive to creating new woodland for timber In order to reduce squirrel damage, it is important to Start inspecting for damage in late February as damage typically occurs in early Spring.  Examine the base of trees for damage. Look for ‘tester patches’ made by squirrels (to which they may well return later). Check young, broadleaf trees as they are particularly favoured by the squirrels.  Oak and beech are quite vulnerable to damage (see image of damaged beech trunk below). Recent research* at Bangor University has investigated the microbiome of the squirrel in relation to its bark stripping activity.  The microbiome of the gut refers to the various micro-organisms found with the intestines.  Analysis of bacterial DNA found in the colon of great (and red) squirrels revealed that grey squirrels had 'oxalobacter' bacteria in their colons.  These bacteria are able to 'release / access' calcium from the tree bark to the squirrels.  Calcium is an important nutrient in terms of bone building and is also involved in muscle contraction. had  a more diverse bacterial population in the colon. These findings may help explain why the grey squirrel 'outcompetes' the red squirrel.  Their more diverse gut microbiome may mean that they can access a greater range of resources. For example, grey squirrels can digest acorns, which red squirrels cannot;  this is possibly associated with tannin content of acorns. In order to reduce damage in a woodland, the number of grey squirrels may need to be managed.  This can be done though trapping or shooting.  Trapping is a legally acceptable and effective way of controlling grey squirrels in most situations. Grey squirrels can be trapped throughout the year though March to September is a good time as food is less abundant. Through autumn, berries, nuts and seeds [natural foods] are available so trapping is less successful.  Details of the various types of traps and their use / placement may be found at: https://greysquirrelcontrol.co.uk/trapping-method.php https://www.britishredsquirrel.org/wp-content/uploads/2016/07/Grey-Squirrel-Best-Practice.pdf https://basc.org.uk/pest-and-predator-control/grey-squirrel-control-with-live-capture-traps/ https://www.britishredsquirrel.org/wp-content/uploads/2016/09/Trapping-Protocol.pdf  https://bpca.org.uk/a-z-of-pest-advice/squirrel-control-how-to-get-rid-of-squirrels-bpca-a-z-of-pests-/188983 To go down the ‘shoot to kill’ route then there are a number of rules and regulations to observe.  Details may be found in the link below : http://www.britishredsquirrel.org/grey-squirrels/grey-control/ It is hoped that eventually a form of oral contraception will be developed, which will offer a non-lethal and humane means of population control. Full details of this research work may be found here

  There are now more deer in the UK than there have been for 1,000 years.  Probably between 650,000 and 2,000,000, of which about half live in Scotland. Dormice like sleeping and can sleep for up to 7 months a year. UK woodlands are home to half the world’s flowering bluebells. There are 15,000 species of fungi, on land, in water and even on plants and animals. Swallows migrate annually to Southern Africa travelling 6,000 miles twice a year. Grey squirrels have become a problem because they were released deliberately, in 1876. Half the deer species in the UK were escapees - three of our six deer species, being Muntjac, Sika, Chinese Water Deer. Conifers have been around so long that they were dinosaur food - about 300 million years. The oldest British trees predate Christianity, Islam and Buddhism. One of the oldest is the Fortingall Yew in Scotland, estimated to be as much as 3,000 years old. Not all conifers have cones - the Juniper, for example, has fruits that are tiny, round, fleshy and berry-like.  

The Gloucestershire Wildlife Trust has spearheaded an initiative to introduce Pine Martens to the Forest of Dean. Some 35 Pine Martens have been released into the forest, between 2019 and 2021.  They have produced litters each year, and there is now thought to a population of some 60 animals.  Pine Martens have two or three ‘kits’ (young) a year.   At one time, Pine Martens were common across the U.K. but the loss of their natural habitat (forest and woodlands) combined with hunting has reduced their presence to remote areas in the North and West. Now, they are a protected species; it is illegal to kill, disturb, sell or possess a pine marten.  Scotland’s population is estimated at 3700 adults.  In the Galloway Forest, the numbers of adults and young are being monitored with thermal imaging cameras.   Pine Martens enjoy a broad diet, ranging from small mammals, insects, eggs and wild fruits - eating that which is most abundant.  They will prey on grey squirrels, and there is the possibility that this may help red squirrels re-establish themselves in more southerly areas.  Forestry and Land (Scotland) have placed artificial pine marten dens in areas where there are red squirrels.  The boxes (with wood shavings to encourage nesting) are placed some 4 to 5 metres off the ground.  The Yorkshire Arboretum has just constructed a special enclosure and introduced a small population of red squirrels.  The enclosure is designed to keep Red Squirrels in and Grey Squirrels out. Two of the females have just produced four kits (young). The Gloucestershire Wildlife Trust is also involved in the Severn Treescapes project.  This is a scheme that involves significant tree planting to link the Wye Valley with the Wye Forest - to create a significant corridor of woodlands, hedgerows, orchards etc across the counties of Gloucestershire, Herefordshire and Worcestershire.   Woodlands TV has a video about the Pine Marten : [embed]https://youtu.be/20RS1M-U008[/embed]

The woodland’s blog has reported on various tree planting initiatives, particularly that presented by the CCC (Committee on Climate change).  This Committee has called for some 1.5 billion new trees to be planted by 2050.   This would require approximately 30,000 hectares of land to be planted each year.  If this were to happen, it would increase Britain’s forest / woodland cover from 13% to 19%; probably the highest level since Roman times.  Sir Harry Studholme, the outgoing chairman of the Forestry Commission has said that such a target is achievable but has urged caution so that mistakes of the past are not repeated.  Read more...

I met up with George Peterken, the man who has probably done more than any living person to protect Britain's ancient Woodlands.  He continues to study woods in fine detail to find out how they actually work and he has written a new book, "Woodland Development" where he explains how a 70-year study of Lady Park Woodland in the Wye Valley has revealed detail on how a broadleaved woodland develops.  Young trees that are just slightly larger than others at the beginning tend to stay larger: "within the first decade, probably sooner, those which are destined to become big trees will have already established themselves as the larger saplings - it's like the boat race: getting an early lead means you probably win in the long run."   Read more...