Content Warning: This article includes discussions of the suffering and death of animals.

In the United Kingdom, Grey Squirrels (Sciurus carolinensis), a species originally native to North America, are sporadically and systematically culled by individuals and organisations, who use the claimed economic and environmental damages caused by these animals as a justification and rationale for the culling. Many people are in favour of the culling of grey squirrels, who are perceived as a threat to the environment and forestry industry of the United Kingdom as it is claimed that they damage trees, adversely affect bird populations, and, perhaps most significantly and notably, out-compete, and serve as a vector of a fatal disease to, the reduced, native populations of Red Squirrels (Sciurus vulgaris). However, these claims, and the damaging nature of the Grey Squirrels, are, alongside the effects and efficacy of the culling itself, disputed by many people, including those who actively oppose the culling of grey squirrels, and the disputes raised by such people are supported by a body of information, opinions and evidence, which is not, according to my personal experience, as commonly known or distributed as the body of information, opinions and evidence in favour of the culling of grey squirrels. In the past, I, with a desire to conserve biodiversity and the natural environment, supported completely the culling of grey squirrels, but was forced to alter my opinion and perspective regarding such culling as the result of becoming more informed about the subject. In this article, I shall attempt to evaluate the current perspectives, evidence and information regarding grey squirrels and the culling of this species, in order to attempt to inform you about the subject, so that you will be able to make your own conclusion regarding whether or not the culling of grey squirrels is justified.

The Methodology of Culling Grey Squirrels.

Grey Squirrels are most frequently culled for the objective of simply reducing and, thus, controlling the number of individuals within a given population, but, in some situations and locations, the objective of the cull may be to entirely eliminate a population. Elimination is easier to achieve, and, therefore, a more frequent objective, in locations that are relatively isolated, as the culled squirrels are not as frequently replaced by squirrels from other populations. Culling is performed via a variety of methods.

Shooting is commonly employed as a method of culling by individuals and small organisations, and is often popular amongst individuals, who perform the shooting as a method of leisure in the form of hunting; such individuals may prefer shooting over other methods as, when performed correctly, is arguably more humane, as a result of the rapidity of the death and suffering of the targeted squirrels, than methods of poisoning and trapping, provides a more intimate and exciting experience during the culling, and ensures the better quality of the pelts and flesh of the squirrels, which can be used and consumed both personally as well as commercially on a small-scale, local basis. However, shooting risks the inducement of extensive suffering if performed improperly, failing to immediately kill the targeted animal, and is not a method that is commonly employed by larger organisations because it is difficult to employ on a level that is sufficient to adequately reduce the populations of grey squirrels, it risks disturbances and injuries to nesting birds and protected species, and may reduce the efficiency of other methods of culling by deterring squirrels from areas where traps have been placed.

The traditional method of culling was the use of Warfarin, an anti-coagulant, to poison and kill the grey squirrels. This method was employed by the use of bait, which was poisoned with the Warfarin, in ‘hoppers’, devices used to prevent larger, not-targeted animals from consuming, and dying as a result of, the bait. This method of culling was popular as it could be effectively deployed on large-scales, was cheaper than alternative methods, and required a relatively minimal amount of effort. Poisoning via warfarin, however, was opposed by many on account of its cruelness as it required days of exposure to kill the grey squirrels, and did so painfully over an extensive period of time. In addition, smaller, non-targeted animals, such as Red Squirrels, were not prevented by the Hopper from consuming, and dying as a result of, the bait, and mammals that predated and consumed the poisoned grey squirrels suffered from poisoning as well, threatening local biodiversity and potentially threatening to induce a trophic cascade via the reduction in the populations of local predators. Despite the objections of many organisations, who argued that the loss of the ability to use the chemical would drastically hinder the culling of squirrels by extensively raising the costs of such culling, Warfarin can no longer be used within the United Kingdom as a method of controlling the populations of grey squirrels as the license for its use and availability, within the European Union, was terminated in 2014.

Trapping is now a popular method of controlling grey squirrels as, like Warfarin poisoning, it is employable on large-scales and considered to be very effective; the ‘Forestry Commission’ claimed in a 2007 Practice Note that a successful trapping session could remove up to 90% of a population of grey squirrels. An additional advantage of trapping is that it can avoid the unintentional killing of non-targeted species as members of such species can be simply released from the trap without issue. Trapping, however, is more expensive, resource-intensive and time-consuming than poisoning as it requires the frequent maintenance, and checking, of the traps by one or, depending on the scale of the cull, more people, and is less successful during Winter and Autumn, when an abundant tree-crop, and the resultant abundance of naturally available food, causes the bait to be less enticing to the squirrels. Traps come in a variety of shapes and forms, including traps that capture single animals and traps that capture multiple animals simultaneously, but the traps are always made of metal, as opposed to wood or plastic, in order to prevent the squirrels from gnawing through the trap; it is recommended that the trap is meshed as to avoid causing considerable discomfort, via internal condensation, to captured animals, especially in damp environments. The design of some traps unintentionally enables captured animals to escape via lifting a door, or escaping when another animal opens the trap from outside. Traps are usually camouflaged and baited in order to ensure that the squirrels are both enticed to enter, and not deterred from entering, the trap. Captured animals are extracted via a sack, which is recommended to be sufficiently thick as to avoid the injury of the extracting human as a result of the defensive attacks of the animal, and, if they are the targeted species, dispatched; species that are not targeted are most commonly released. There is no definitive method of dispatch, but the most commonly employed and recommended method is a single blow to the back of the neck of the animal with a blunt instrument, which is a rapid and relatively humane method of killing the animal. Trapping can be considered morally problematic as, despite laws ensuring that traps are checked frequently for captured animals, captured animals, including those that are members of species that are not targeted by such traps, can suffer from exposure and considerable stress whilst in the trap, and both improper trapping and improper dispatching can result in large amounts of suffering for the captured animals, as the result of stress, injuries, pain and death.

Recent plans and projects to reintroduce the Pine Marten (Martes martes) , which is a species that predates squirrels, including the ‘Pine Marten Recovery Project’ and a considered reintroduction of pine martens to the Forest of Dean by the ‘Gloucester Wildlife Trust’, have used the control of grey squirrel populations as a reason for doing so. Whilst some people may not consider this a method of culling, as it does not involve the direct and active killing of the grey squirrels by Humans, I have chosen to discuss it as a method of culling because such reintroductions are the planned actions of Humans with the intention of reducing grey squirrel populations via a methodology that involves the killing of grey squirrels; I do not believe that this method differs sufficiently greatly from other methods of culling for it to be not considered as a method of culling. The presence of pine martens has been found to reduce the populations of grey squirrels, whilst having no significant detrimental effect on the populations of red squirrels; this is because red squirrels, who have ‘co-evolved’ with pine martens, adapt their behaviour in order to better avoid pine martens, whilst grey squirrels, who have not ‘co-evolved’ with pine martens, fail to make suitable adaptions to their behaviour and are predated upon by pine martens more easily. Reintroducing pine martens would also be beneficial for environmental and conservation reasons as it would increase the biodiversity of predators, potentially providing an increased security to the eco-system as well as potentially providing ecological functions that are not performed by other predators, and would help to restore the populations of pine martens, which have historically been greatly reduced in England and Wales as the result of habitat-loss via deforestation and hunting by Humans for the fur of the pine martens; the restoration of pine marten populations would be beneficial for the aforementioned increase to the biodiversity of predators, but also for the cultural and aesthetic values that they would provide to Humans. However, some people may object to the reintroduction of pine martens as the result of the potential threat to poultry, game birds, and young lambs; an Irish councillor claimed that they posed a risk to children, but no substantial evidence exists to support his claim, which was partly caused by confusion regarding an attack on a baby in England by a fox (Vulpes vulpes). The Pine Marten may also pose a threat to wild populations of bats and birds, particularly those that nest on the ground. Many people also object to the reintroduction of pine martens for moral reasons because the presence of pine martens would cause members of the species that they prey upon to experience an elevated level of stress, and to potentially experience extreme pain and suffering as they are injured and killed by the pine martens; moral considerations also extend to the pine martens themselves, who may suffer from persecution from game-keepers, farmers and hunters.

History of the Grey Squirrel in the United Kingdom.

Grey Squirrels were first introduced to the United Kingdom when they were released in 1876, with further releases occurring more frequently during the 1890s; an English Duke, Herbrand Russell, has been noted as a key figure in these releases, having been responsible for the release of grey squirrels into both Woburn and Regent’s park. Within a period of 25 years after the first release in 1876, grey squirrels had colonised an area of around 300 miles, including areas previously inhabited by red squirrels; while some populations of red squirrels were displaced by the Grey squirrels, the national population of red squirrels was already undergoing a decline, so many grey squirrels simply began to inhabit areas that were already vacant of red squirrels. The spread of grey squirrels was directly facilitated and aided by Humans, as evidenced by the fact that many populations of grey squirrels are genetically distinct, indicating that they have separate ancestral origins within the United Kingdom, and that the population of grey squirrels in Aberdeen is most closely related to the population in Hampshire, which represents a distance that could not been travelled by a grey squirrel without Human intervention. The expanding presence of grey squirrels put pressure on the populations of red squirrels via competition for resources and the potential transmission of the fatal ‘Squirrelpox’ virus, but it cannot be attributed as the sole cause of the decline of red squirrels in the late nineteenth and early twentieth centuries, as red squirrels, during these periods, were culled by Humans, as a result of the economic damage of the squirrels to trees, until 1927, and were exposed to a series of harsh winters and epidemic diseases; in addition, between the years of 1900-1920, only four of the forty-four districts, where red squirrels were affected by Squirrelpox, were reported as containing grey squirrels, potentially indicating that the virus was also spread by alternative vectors.

In 1931, at which point the grey squirrels had colonised an area of approximately ten thousand square miles, an ‘Anti-Grey Squirrel’ campaign was organised by ‘The Field’ magazine, and the destruction of grey squirrels was encouraged by the ‘Ministry of Agriculture, Fisheries and Food’, or ‘MAFF’; despite these measures, however, the range of grey squirrels within the United Kingdom doubled during the next six years. These measures were followed by a mass culling during the 1940s and 1950s, which was composed of the establishment of ‘Grey Squirrel Clubs’, which shot grey squirrels with shotgun cartridges provided freely by the MAFF, and a bounty scheme by the ‘Forestry Commission’, which paid a bounty of, at its maximum value, two shillings for every tail of a grey squirrel taken to a local police station. The mass culling killed over one million grey squirrels at the cost of around £3 million, but failed to effectively control the national population of grey squirrels. In 1973, after a successful media campaign by the Forestry Commission in opposition to the grey squirrels within the United Kingdom, the British Government permitted the poisoning of grey squirrels with Warfarin in areas that did not have an inhabiting population of red squirrels, and such poisoning remained the primary method of culling until the license for its use was terminated in the European Union in 2014.

In Anglesey in 2015, the population of grey squirrels was officially declared to have been entirely eradicated from the island after a successful cull that began in 1998. The cull involved the participation of over two hundred volunteers, a dedicated project team and various contractors, and received support from the general public, although it was opposed by many individuals and groups. No poisoning was employed during the cull, which was performed primarily through the use of trapping. During the cull, the population of red squirrels on Anglesey increased in size from forty to around seven hundred individuals, providing evidence that the elimination of grey squirrels is beneficial to native populations of red squirrels, although this increase in size was aided by reintroductions of red squirrels by Humans, and other conservation methods, such as the construction of nest-boxes. As Anglesey is an island, and is, thus, relatively isolated from the mainland populations of grey squirrels, the elimination of grey squirrels there was facilitated by the greatly reduced immigration of grey squirrels to the island; however, proponents of the cull suggest that the success of the cull could be replicated throughout the United Kingdom even in the absence of such isolation. The success of the cull on Anglesey encouraged the provision of £1.2 million of funding to the culling of grey squirrels in the neighbouring county of Gwynedd.

The culling of grey squirrels continues to the present and is supported by many organisations and members of the British public, although opposition to the practice is growing, with a petition to “Stop the UK grey squirrel cull” achieving around 140,000 signatures in 2015, and alternative methods of controlling grey squirrel populations, and aiding red squirrel populations, are becoming more popular.

Arguments in Favour of the Culling of Grey Squirrels.

There are a variety of arguments in favour of the culling of grey squirrels. Although these arguments are not isolated from each other, I shall discuss them separately in order to maintain clarity within this article. For the sake of brevity, unless stated otherwise, it can be assumed that each argument is in favour of culling grey squirrels as the reduction in population of the grey squirrels would mitigate the negative effects that are caused by the grey squirrels and discussed within each argument.

Grey Squirrels predate birds, chiefly by consuming their eggs, and, thus, it is feared by some people and organisations that the presence of grey squirrels may adversely affect the populations of various bird species within the United Kingdom. This argument is supported by a research project by the ‘Game and Wildlife Conservation Trust’, which, after removing grey squirrels from random groups of woods, found that open-nesting birds experienced a 20% increase in the production of successfully fledged offspring when grey squirrels were removed from an area. However, other studies, whilst supporting the idea that grey squirrels do adversely effect birds, found that such adverse effects were not overly harmful to the populations of birds, and were likely to not be a major contributing factor in the decline of any of these populations. The adverse effects of grey squirrels include nest predation, the mitigation of the benefits of increased canopy-cover for species that are sensitive to nest predation, and the restriction of access to food for birds as a result of competition with grey squirrels; in urban areas that provide supplementary feeding stations for grey squirrels, grey squirrels are able to out-compete birds and restrict the intake of food by the birds by over 90%. A criticism of the research surrounding this argument is that no extensive research has been performed that takes into consideration the indirect effects of grey squirrels that grey squirrels have on bird populations, such as potential afforestation, which could provide a greater abundance of suitable nesting-sites for birds, via the growth of stored seeds that the grey squirrels have spread, which may benefit or damage bird populations.

An economic reason for the culling of grey squirrels is the damage that they cause to trees by stripping their bark; the damage that the stripping of bark causes to trees is estimated to result in an annual cost of £10 million to the United Kingdom’s forestry industry. Grey squirrels strip the bark of the trees in order to access and consume the sap of the phloem of the tree, and the stripping of bark, if an unbroken ring of bark is stripped from around the trunk of the tree, can prevent the tree from transporting nutrients and glucose to the roots, killing the tree. The stripping of bark also leaves the tree vulnerable to fungal infections, which can weaken the tree structurally; trees that are damaged by the stripping of their bark are of a reduced value when harvested for timber as the result of the internal weaknesses incurred by the stripping of the bark. The stripping of bark by grey squirrels is most often performed in the late Spring and in Summer, when the volume of the sap, and width of the phloem, of trees are at their greatest. It has been suggested that agonistic social encounters, caused by high population densities may be a trigger cause for the damage caused by grey squirrels to the trees; juveniles are suggested to have a greater role in these agonistic social encounters and resultant damages to trees via the stripping of bark, but the stripping of bark is not restricted to any age or sex of grey squirrel. It is not known for certain as to why grey squirrels consume the sap of trees, but a suggested hypothesis states that they may do so primarily to alleviate a deficiency of calcium. The stripping of bark may also have potentially adverse effects ecologically as the squirrels preferentially strip the bark of certain species of trees, altering the biological composition of forested areas and potentially threatening vulnerable species in mature forests. The use of this argument as part of the justification for the culling of grey squirrels may be rejected by some, including those in support of such culling, as it could also be used to justify the culling of red squirrels, who are more commonly perceived as a desirable species, and whose potential, resultant increase of population is also used as a reason for the culling of grey squirrels, as red squirrels also strip the bark of trees, and such stripping of bark was an argument used to justify the historical culling of red squirrels, which was an attributing factor in the decline of their national population. The argument may also fail to provide sufficient justification for the culling of grey squirrels as, since the cheap method of Warfarin poisoning can no longer be legally employed, the costs of any extensive culling may not be sufficiently off-set by the reduction in the costs that would otherwise be incurred via the damage of timber. In addition, culling can exacerbate the damage to trees as the resultant reduction of the population density of the grey squirrels may prompt an increased rate of immigration and production of offspring, which, in turn, would result in a greater number of agnostic encounters, triggering an elevated level of the stripping of bark.

A prominent argument in favour of the culling of grey squirrels is that the presence of grey squirrels reduces the presence of the native red squirrels, which have a cultural, aesthetic and ecological significance within the United Kingdom. The population of over two million grey squirrels is currently much greater in than that of the red squirrels, which is composed less than one hundred and forty thousand individuals, and grey squirrels inhabit much of the area that was historically inhabited by, but is now absent of, red squirrels, whose national population and range has undergone a large reduction; the presence of either species does not necessarily exclude the presence of the other, as areas exist where both species are present. There is no significant difference in the ecological niches of the two species, so they are in competition for resources; for example, grey squirrels will sometimes consume the stored caches of food of red squirrels. This competition does not usually result in frequent or significant, direct inter-species interactions, such as fighting, but does result in the increased scarcity of food for both species, although this increased scarcity is relatively greater and impacts the red squirrels far more severely than it does the grey squirrels. There have been a number of suggested reasons that cause grey squirrels to out-compete red squirrels, although none of these reasons wholly explains the issue in a satisfactory manner, and it is likely that there are multiple, interacting, attributing factors. Such reasons include the fact that grey squirrels can more efficiently consume acorns than red squirrels as the result of their superior physiological ability to neutralise acorn phytotoxins, which is beneficial in forests that are dominated by oak trees (Quercus), and the fact that grey squirrels gain more body-mass during Autumn than red squirrels, giving the grey squirrels a greater rate of survival during the following Winter as well as a greater likelihood of successful reproduction during the following Spring. In addition, red squirrels have greater amounts of glucocorticoid hormones in their faeces when grey squirrels are present, indicating an elevated level of stress, and grey squirrels may spread parasites to populations of red squirrels, decreasing the overall fitness of red squirrels. The presence of grey squirrels does not have any significant effect on the residency or population turnover rate of red squirrels, but does result in a reduction in the overall fitness, juvenile recruitment rate, and reproductive success of red squirrels, which can eventually result in the severe reduction, and potential exclusion, of the population of grey squirrels in an area over an extended period of time. Criticisms of this argument include the claim that it may be possible for both species of squirrel to inhabit an area without an inevitable exclusion of the red squirrels, which is supported by the existence of areas where both species currently are present and the fact that grey squirrels are not the sole, attributing factor in the decline of red squirrels and have, in many areas, merely occupied an area in the absence of an inhabiting population of squirrels instead of displacing a population of red squirrels. An additional criticism of this argument regards the fact that the researched areas, where grey squirrels and red squirrels both inhabit, are habitats that are smaller, more fragmented and of significantly lesser quality than the areas, where only red squirrels are present, so the problems afflicting the populations of red squirrels in the former areas may be the result of their poorer quality habitat, as opposed to the presence of grey squirrels.

Grey squirrels may also threaten red squirrels, and have been further responsible for the historical decline of red squirrels, as they act as a vector of the disease, ‘Squirrelpox’. Squirrelpox is more formally referred to as ‘Squirrel poxvirus’, which is abbreviated to ‘SQPV’, and is a viral infection that induces swollen legions on the paws, flanks and head of infected, symptomatic squirrels, and is lethal to the majority of infected red squirrels within two weeks. SQPV is occasionally referred to as ‘Parapox’, as the virus was previously believed to belong to ‘parapoxvirus ‘ genus of viruses, which are responsible for the ‘Orf’ disease that is associated with domesticated animals; however, recent research indicates that squirrelpox may actually, instead, belong to another genus within the chordopoxvirinae subfamily of viruses. Grey squirrels can be infected by the virus, but usually do not develop any adverse symptoms as the result of being infected, with only one fatal, potential infection by SQPV of a grey squirrel having been reported within the United Kingdom at the time during which this article was written. Red squirrels frequently become symptomatic after being infected by squirrelpox, and symptomatic individuals usually die within two weeks of developing symptoms, although some individuals have been reported as surviving the infection, and antibodies that protect against squirrelpox have been found in individuals and populations, suggesting that the virus is not necessarily fatal, and that it may be possible to inoculate red squirrels against SQPV. The virus is believed to be spread by contact, but the exact methods of transmission are neither fully identified nor fully understood; research suggests that red squirrels can spread the virus amongst each other via saliva and faeces, but grey squirrels are unable to spread the virus to red squirrels via these routes. The virus may also be transmitted via aerosol particles, parasites, and the leaked fluid of lesions that have been induced by squirrelpox; parasites are currently believed to be the most likely vector between the two species of squirrels. Squirrelpox was first isolated and identified within the United Kingdom in the year of 1980, but epidemics of a virus that produce similar symptoms, which is believed to be, in fact, the same virus, amongst red squirrels have been reported since the beginning of the twentieth century. It is believed that grey squirrels may have introduced the disease to the United Kingdom as the disease was not reported within the United Kingdom until after the introduction of grey squirrels, and antibodies to squirrelpox have been found in grey squirrels in North America, potentially indicating that squirrelpox may be closely related to the squirrel fibroma virus that infects squirrels within the United States of America, but this belief can be disputed as there is no obvious correlation between the spread of grey squirrels and the spread of squirrelpox amongst populations of red squirrels; as mentioned earlier in this article, during the period of 1900-1920, only four of the forty-four districts, where squirrelpox was present, were reported as containing grey squirrels. A 1930 paper by Adrian Middleton also disputes the claim that SQPV originated from grey squirrels, noting that, according to the research of Middleton, only 5 of the 14 districts where squirrelpox was ‘present’ or ‘severe’ contained grey squirrels, and that there is no indication that epidemics of the disease spread from the points of introduction of the grey squirrel; in addition, Middleton reported that some areas, where the disease first decreased in prevalence, were actually relatively close to the Woburn Centre, a point of introduction. Middleton and his paper did not dispute the role of the grey squirrel as a carrier of the disease. A similar disease to squirrelpox has been reported as having infected red squirrels in Spain, where no established populations of grey squirrels exist, further disputing the claim that grey squirrels introduced squirrelpox; however, the disease in Spain differs from squirrelpox as it, unlike squirrelpox, does not result in the formation of lesions on the eyelids and mouth of infected individuals. The role of grey squirrels as a carrier and vector of squirrelpox, by itself, cannot be used as a justification for the complete eradication of grey squirrels because a population of grey squirrels must achieve a threshold density before the squirrelpox virus can be transmitted from that population to red squirrels. The use of the role of grey squirrels in the transmission of squirrelpox to red squirrels as a justification for culling is also disputed as a result of the earlier discussed disputations regarding the origin of the disease and the ability of grey squirrels to spread it; in addition, the development of antibodies against squirrelpox by infected grey squirrels may prevent their future infection and, therefore, their future transmission of the disease. Those who dispute the role of grey squirrels in the spread of squirrelpox often propose alternative methods, which could be used instead of the culling of grey squirrels, of controlling the spread and harmful effects of SQPV. Such alternative methods include the hygienically superior management of feeding stations for red squirrels, and shall be discussed in more detail later in this article.

Arguments in Opposition to the Culling of Grey Squirrels.

As mentioned previously throughout this article, there also exists an abundance of arguments in opposition to the culling of grey squirrels. These shall now be discussed in a manner, striving to maintain both brevity and clarity, similar to the manner in which I discussed the arguments in favour of the culling of grey squirrels.

The culling of grey squirrels can be opposed for ecological reasons as grey squirrels contribute to forest regeneration by dispersing and burying the seeds of trees as stores of potential food; grey squirrels may bury over ninety percent of the seeds that they gather, and around thirty percent of these seeds are never recovered by the squirrels, allowing them to potentially grow. The role of grey squirrels in forest regeneration is made more efficient by the fact that grey squirrels consume seeds that are infected, rotting or otherwise damaged first before they consume healthier seeds, which are more likely to germinate successfully when planted. The consumption of infected seeds may also help to control the population and spread of the parasites of trees, and this control is further enhanced by the grey squirrel’s direct consumption of infecting larvae and insects. Grey squirrels may be more effective at causing forest regeneration than red squirrels as red squirrels bury a smaller portion and variety of their gathered food, and have not been observed to selectively consume damaged seeds. As a potential case-study of note, the ‘Fletcher Wildlife Garden’, which is located in Canada, attributes the doubling of its population of walnut trees during the two-year period of 2004-2006 to grey squirrels. The stripping of bark from trees by grey squirrels may also play a beneficial ecological role as the areas of damage can provide suitable habitat for fungi and invertebrates, which, in turn, provide a potential food-source for other organisms. However, this argument may be opposed because the ecological benefits of grey squirrels may be outweighed by their harmful effects on red squirrels, who, being a native species to the United Kingdom, are more likely to have unique, evolutionarily influenced ecological functions within the United Kingdom, which could have a currently unknown importance on eco-systems, and because the majority of research on the ecological role of grey squirrels has been performed in North America, where they are a native species, and, thus, not considered to be an invasive species; grey squirrels may have a different, less beneficial ecological role in the different environment of the United Kingdom.

Another argument in opposition to the culling of grey squirrels is the idea that, although, grey squirrels are not native, this fact does not necessarily justify the culling of the animals, nor does it necessarily signify that they are environmentally harmful or ‘invasive’. There are many examples and case-studies, which prove that non-native species can result in the significant, and potentially widespread, loss of biodiversity and ecological functions, resulting in cultural, economic and environmental damages. However, some non-native species have had no considerable impact on the new geographical areas that they inhabit, and other non-native species have had positive effects on their new environments; the Asian Shore Crab (Hemigrapsus sanguineus), which arrived in North America, where it is not native, in 1988, has established populations, which have greater densities than the populations of Asian shore crabs in their original geographic locations, along the coast of North America, yet the density of Asian shore crabs is positively correlated with the richness of native species, indicating that the Asian shore crabs do not have any significant, detrimental effect on native, North American species. Because of the fact that a species that is not native is not necessarily harmful, some people, scientists, and organisations have suggested that the term of ‘invasive species’ should be reserved for non-native species that have been proven to induce significantly harmful effects within their new, geographic locations, and that we should not attempt to remove or control non-native populations on the basis of such populations not being native, as these populations may not be causing an amount of harm that would justify the costs and negative effects of their removal and control, and they may, potentially, have an overall positive effect within their new environment. This argument is relevant to the issue of the culling of grey squirrels as, if it is not proven that grey squirrels have an overall negative impact within the United Kingdom, the fact that they are not native may not justify the culling of the species. In addition, the red squirrels within the United Kingdom may be considered by some to be non-native as their populations have been historically supplemented by the introduction of individuals from Europe and, thus, represent a mixed genetic stock, which is not genetically dissimilar to the genetic stock of Europe, which is descended from various, ancestral, geographic origins; if not being native is a sufficient justification for the culling of grey squirrels, then it is a sufficient justification for the culling of red squirrels, and the culling of red squirrels is considered to be unjustified and undesirable by many people, including the proponents of the culling of grey squirrels, many of whom support such culling in order to protect and restore populations of red squirrels. The argument is contributed to by the growing belief that conservation should not rely entirely on preserving the most ‘natural’ state of being of eco-systems, and that changes should be considered, and even created, in order to promote the greatest benefits to and from ecosystems; the sole devotion to preservation may be ignoring the fact that eco-systems are dynamically changing entities that have historically, and prehistorically, been greatly altered, and continue to be continuously altered, both with and without Human intervention. However, this argument can be refuted as empirical research, as discussed earlier in the article, has established that grey squirrels do, indeed, cause negative effects within the United Kingdom, so they could possibly be considered as an invasive species, thereby justifying the culling of the species, and, because of the aforementioned negative effects, the argument that grey squirrels are not native is not actually required to justify the culling of grey squirrels. In addition, whilst the populations of red squirrels in the United Kingdom may be descended partly from European populations, the species itself can, unlike that of the grey squirrels, be considered native to the United Kingdom; the differences between the original populations and European-descended populations are unlikely to have any significant effect on the ecological role and function of the red squirrel, a species with an extended historical presence, within the United Kingdom. Another rebuttal against this argument is that our society, its constituent elements, and the scientific community currently do not have access to a sufficient amount of knowledge regarding eco-systems and the relevant, attributing factors, and, thus, preservation of the natural state of being of eco-systems should be the objective of conservation, unless and until the effects of any changes can be sufficiently well understood, in order to prevent any unintentional damages to the eco-systems and the services that they provide, and to ensure that the eco-systems continue to exist and provide such services in the future; the culling of grey squirrels, who represent a potentially harmful change to the eco-systems of the United Kingdom, could, therefore, be justified by this rebuttal in order to promote the preservation and well-being of such eco-systems.

The culling of grey squirrels is also opposed for an extensive variety of moral reasons. One such reason is that the advocation of culling grey squirrels as the result of the species not being native to the United Kingdom may both intentionally and unintentionally normalise and encourage xenophobic tendencies and ideologies, potentially creating social divides and promoting hate crimes between people, who are ‘native’ to the United Kingdom, and more recent immigrants to the United Kingdom; the advocation of the culling of grey squirrels, in this case, has the potential to incur such effects as it uses the fact that a population is not native as a justification for the elimination and control of that population, and that justification could be potentially applied to people. However, no empirical research has been performed in order to determine if there is any correlation between social tensions, the culling of grey squirrels, and relevant, related factors. The culling of grey squirrels also has the potential to, and currently does, inflict large amounts of suffering upon individual animals, which are not necessarily grey squirrels, as other species can be killed or injured unintentionally by the methodology of such culling. Although the particularly painful and widespread method of poisoning via Warfarin is no longer legally employed, the other methods of culling still have the potential to incur large amounts of suffering; for example, trapping can result in the exposure of animals to harsh conditions for potentially extensive periods of time, and shooting, or a chosen method of dispatching an animal, may fail to kill the animal sufficiently rapidly to avoid the affliction of extensive suffering. Suffering may also be incurred indirectly as the process of culling may result in the elevated stress of populations; an example of indirect suffering that was discussed briefly before in this article is that culling, by reducing the population densities of squirrels, can result in a greater number of agnostic encounters as the result of a greater rate of both immigration and the production of offspring. Even if culling could be performed painlessly, it would likely still be opposed for moral reasons by some because killing animals is contrary to their desires; animals strive vigorously to avoid death and to survive, indicating that they have a desire to not be killed, even if such a desire is not achieved via rational or conscious thought. By culling the grey squirrels, we prevent their future, potential, personal positive emotions, feelings, and developments that they may experience, and we set a potential precedent for the violation of other desires, including many Human desires that it would be commonly be perceived as immoral to violate. In addition, by advocating in opposition to the culling of grey squirrels, and by advocating for the consideration of their welfare, we may encourage compassion and consideration within our society and amongst people, which would promote safer, enjoyable and better developed social conditions, and we would avoid creating encouragement, justifications and precedents for undesirable actions and behaviours, which have the potential to be harmful. Opponents to this argument could argue that, although sometimes performed incorrectly, the methodology of the culling is performed correctly during the majority of cases, minimising the suffering inflicted upon animals. In addition, culling may, despite the increased prevalence and severity of stress amongst culled populations, mitigate suffering as it decreases the density of populations, reducing agnostic social encounters and the transmission of diseases. Some may also argue that those opposing the culling of grey squirrels for moral reasons may be overly anthropomorphising the animals by assuming that the animals possess Human characteristics and emotions; for example, whilst animals avoid death, because the relevant behaviours are likely innate and not rationally adopted and performed, the desire of the animal for its continued survival is not consciously maintained, and, thus, may potentially merit different moral considerations, which could potentially justify the culling of grey squirrels, than the consciously maintained desire of a Human. A potential point of discussion is that grey squirrels also have a cultural and aesthetic significance, and are liked by more people within the United Kingdom than disliked, but it is difficult to measure how this compares to their ecological and economic effects, and the cultural and aesthetic significance of red squirrels.

Some people do not believe that the current culling of grey squirrels is justified due to the lack of efficacy and the economic costs of such culling. The culling of grey squirrels has historically been unable to effectively control the national population of grey squirrels, even when widely supported and extensively funded; as discussed earlier in this article as part of the history of grey squirrels within the United Kingdom, a mass culling, which was organised by the MAFF and Forestry Commission and performed, during the 1940s and the 1950s, at an expense of over £3 million, failed to effectively control the national population of grey squirrels, despite the killing of more than one million grey squirrels. The culling of grey squirrels has also lacked efficacy when performed on smaller scales; despite trapping approximately 2200 squirrels, a three year period of culling in Thetford Forest failed to reduce the population of grey squirrels, and a long-term campaign of poisoning in Lady Park Wood did not reduce or prevent woodland damage, which, in fact, increased during the cull. Some research does indicate that poisoning, but not shooting or trapping, may be, if employed extensively and effectively, able to remove a population of grey squirrels in some situations, but the poisoning of grey squirrels with Warfarin can no longer be legally performed in the United Kingdom, and areas can be recolonised by grey squirrels within a period of three months, or within a period of a single month, if the area is not sufficiently isolated. In the majority of cases, culling results in only a temporary decrease in population density, and populations of grey squirrels are capable of recovering to ‘pre-cull’ levels within a period of three to ten weeks. It is believed that populations of grey squirrels are resilient to culling as such populations increase their reproductive rate in response to the culling, and individual, and populations of, grey squirrels will rapidly immigrate, and recolonise, areas, where the existing populations of grey squirrels has been reduced; as the result of such immigration, the culling of grey squirrels can incur negative effects, such as the increase in agnostic social encounters between grey squirrels, which promotes the greater stripping of tree bark, and the greater spread of diseases, such as squirrelpox, as infected individuals move from one area to another. In addition, localised culling may actually result in a greater density of grey squirrels within the targeted area as the result of the promotion of immigration of grey squirrels into that area. The culling of grey squirrels can also have a large economic cost, especially since the cheapest method of culling, poisoning with Warfarin, is no longer a legally viable option; the expenses required for the culling of grey squirrels to sustain red squirrels in Thetford Forest was estimated, in 2002, to be approximately £300,000 per annum, and, in Redesdale Forest, the required expenses would be £200,000 per annum. The economic costs of culling can increase over the duration of a cull as the surviving individuals become more wary, and less easily killed. Proponents of this argument may argue that the inefficacy, and other problematic elements, of the culling of grey squirrels does not justify the costs of such culling, and that such funding should be diverted to employing alternative methods of sustaining and protecting populations of red squirrels, or to resolving other issues. People, who oppose this argument, could argue that the culling of grey squirrels has been proven to be successful in some situations, such as Anglesey, where the population of grey squirrels has been completely eradicated and where the population of red squirrels, as the result of the eradication of the grey squirrels, as well as the reintroduction of individuals and the employment of other methods of conservation, has experienced a large increase. However, the success of the culling in Anglesey is largely attributed to its relative geographic isolation, which mostly prevents immigration into the area by external populations of grey squirrels, and the culling of grey squirrels would not be effective without such geographic isolation, although some people, who were involved with the culling on Anglesey, have claimed that the success of Anglesey could be repeated in areas that lack geographic isolation. The argument could also be opposed as it is possible to argue that the conservation of red squirrels, their ecological function, their cultural and aesthetic values, and their eco-systems justifies the economic costs of the culling of the grey squirrels. In addition, some people may claim that the implementation of the more effective employment and management of the culling of grey squirrels, as well as the employment of relatively new methods, such as the reintroduction of pine martens, may result in a greater success of such culling, although not much extensive evidence or research exists to justify this claim.

A more controversial argument in opposition to the culling of grey squirrels is that the protection and expansion of the populations of red squirrels does not justify such culling as populations of red squirrels, while threatened in the United Kingdom, are globally abundant, successful and not threatened, and, due to the historical supplementation of red squirrels with individuals from Europe, there is no real distinction between the populations of red squirrels in the United Kingdom and the populations of red squirrels in Europe; even if red squirrels were to become extinct within the United Kingdom, populations could be re-established with individuals from Europe, and there would be no significant loss of genetic biodiversity. In addition, grey squirrels could be considered more ecologically beneficial than red squirrels due to the greater contribution of grey squirrels to forest regeneration. This argument could be opposed because it does not consider the cultural and aesthetic significance of red squirrels, and because red squirrels may perform ecological roles, which are currently unknown and not performed by grey squirrels, and the loss of the performance of such ecological roles could result in harmful effects in eco-systems, and the loss of biodiversity, including elements of such biodiversity that are endemic to the United Kingdom. The claim that there is no real distinction between the populations of red squirrels in the United Kingdom and the populations of Europe may also be incorrect as an unique genetic haplotype was discovered amongst red squirrels in Ceredigion.

Alternative Methods to the Culling of Grey Squirrels.

It has been suggested that the stripping of tree bark by grey squirrels, and the resultant economic damages that such stripping incurs, could both be mitigated without the culling of the grey squirrels via the implementation of superior silviculture techniques, including the planting of less susceptible species of trees and the planting of trees in lesser densities, reducing the vulnerability of the planted trees to grey squirrels. This would be a relatively inexpensive method of reducing the economic damages incurred by grey squirrels, and would, unlike culling, being unlikely to unintentionally promote a greater extent of damage to the trees via the increased number of agnostic social encounters as the result of a greater rate of the immigration of grey squirrels into the area. In addition, this method could be considered preferable to the culling of grey squirrels as the expenses required to effectively cull grey squirrels can often exceed the economic damages that are desired to be mitigated, especially since the legal prevention of the use of Warfarin for poisoning. However, there is not much research regarding the efficacy of the implementation of such silviculture techniques in reducing the damage to trees by grey squirrels, and it is unlikely that the implementation of such techniques could entirely prevent the damage of trees by grey squirrels, although the complete prevention of such damage may be undesirable as it could potentially prevent the formation of suitable habitat for species of fungi and small animals that serve as a source of food for larger organisms.

An alternative method of protecting red squirrels and their populations against squirrelpox would be the inoculation of such populations against the disease. A vaccination against squirrelpox does not yet exist, but the ‘Moredun Research Insititute’ has been researching the potential development of such a vaccination since 2010, having received around £300 thousand from the ‘Wildlife Ark Trust’ charity, as well as additional funding from other groups; according to the Wildlife Ark Trust, an effective vaccine candidate had been discovered by 2012, but the candidate still needs to be modified before it can be used to inoculate populations of red squirrels. It is currently believed that a vaccination against squirrelpox would likely utilise the entire virus instead of its antigens, as no vaccination has been developed, which uses the antigens of a virus instead of the virus itself, against viruses that are related to squirrelpox; the virus in the vaccination would likely be active, as, amongst viruses that are related to squirrelpox, active viruses are more effective at producing an effective immunity than inactive viruses. Another currently held belief is that a related virus could not be used to inoculate squirrels against squirrelpox, as the immunity, which is induced by a vaccination against a virus within the chordopoxvirinae subfamily, will only be developed against that particular virus; this could potentially signify that a vaccination against squirrelpox would have the potential to become pathogenic, unintentionally threatening individuals and populations of red squirrels with infection from squirrelpox, especially since an active form of the virus would be most likely to be used within the vaccination. The potential risk of a vaccination becoming pathogenic could be mitigated by using an avirulent or attenuated strain of the active virus, reducing the likelihood of the vaccination becoming pathogenic whilst still allowing the vaccination to provide an effective immunity to vaccinated individuals. Attenuated strains of a virus can be produced by removing the genes which control the virulence of the virus in vitro, or by removing the genes using recombinant DNA techniques. The production of an attenuated strain of a virus in vitro is unreliable as the removal of the genes, which control virulence, is entirely dependent on chance, and the virus can be so weakened by passage in vitro that it may not produce an effective immunity; recombinant DNA techniques are more reliable, but much more expensive. The inoculation of populations of red squirrels is currently impossible due to the lack of an appropriate vaccine, but such inoculation may be opposed as the development of an appropriate vaccine is estimated to have a considerable economic cost of over £400 thousand for a three-year period of development using recombinant DNA techniques, or a cost of £90 thousand per year of development of an attenuated strain in vitro; in addition, further costs would be incurred during the testing and registration required to ensure the safety of the vaccination. Inoculation may also be opposed as a result of the aforementioned potential risk of the vaccination becoming pathogenic, and because the delivery of such a vaccination, which would likely require the capture, and injection, of wild squirrels, could potentially threaten and harm individual squirrels with induced stress, especially if the process of vaccination would have to be repeated. In addition, some people may oppose the inoculation of squirrels against squirrelpox for moral reasons as the development of the vaccination, and the following research to ensure its safety, may require the testing of live animals, which could suffer greatly as the result of an induced infection.

The spread and prevalence of squirrelpox amongst and within populations of red squirrels could also be mitigated without the culling of grey squirrels by the superior management of, and consideration of hygiene regarding, feeding-stations, which are used in some locations to provide supplementary food to red squirrels in order to aid their survival, and to encourage them to be in locations where they can be seen and enjoyed by people. Many of these feeding-stations utilise shared feeders, and this can result in the transmission of squirrelpox from red squirrels to other individuals in their population as squirrelpox can be transmitted via the saliva of infected individuals; to mitigate the risk of transmission in this manner, it is recommended that shared feeders should be cleaned chemically every day. The use of ‘scatter-feeding’, which involves placing food freely in scattered, separate locations, instead of using a feeder or a single area, instead of shared feeders may be a more effective method of reducing the spread and prevalence of squirrelpox because, unlike a shared feeder, scatter-feeding does not promote the extreme proximity of multiple red squirrels, which would promote the transmission of squirrelpox through a variety of mediums, and would greatly reduce the likelihood of the transmission of the disease via saliva. Despite the risk posed by the transmission of squirrelpox via saliva, the use of shared feeders may be prioritised over the use of scatter-feeding, however, as shared feeders are more likely to ensure the visibility and presence of red squirrels for the enjoyment of people. Another method of reducing the risk of the transmission of squirrelpox at feeding stations is to ensure that any individual red squirrel at any given feeding station has access to only an amount of food that can be quickly buried or consumed, ensuring that the extended presence of the red squirrel does not result in a greater likelihood of its transmission of, or infection with, the squirrelpox virus. The superior management of feeding-stations would be both easy and cheap to implement, but not much research has been performed regarding its efficacy in reducing the prevalence and spread of the squirrelpox virus, and it is extremely unlikely that the superior management of feeding-stations could offer total protection from the virus or that it could completely prevent its transmission, prevalence and spread.

Other methods of conserving red squirrels could also be utilised instead of the culling of grey squirrels. It has been suggested that the creation of a greater number of conifer (Pinopsida) forests and plantations, and the expansion of existing conifer forests and plantations, would benefit the national population of red squirrels by providing a greater amount of habitat for populations to survive, and establish themselves, within. Although the most suitable habitat for red squirrels is similar to that of grey squirrels, due to their similar ecological niche, and it is more difficult for both species to survive in conifer forests and plantations due to a relative scarcity of food, in comparison to other habitats, within such habitats, it has been suggested that red squirrels are able to survive within conifer forests and plantations more successfully than grey squirrels as the smaller size of the red squirrel enables the species to better cope with the relative scarcity of food; as a result, populations of red squirrels, within conifer forests and plantations, are unlikely to be significantly, adversely affected by competition from grey squirrels; the competitive advantage provided to grey squirrels by their superior physiological ability to neutralise acorn phytotoxins would also be much less significant within conifer forests and plantations. It has been advised that multiple species of conifer should be planted within these forests and plantations in order to ensure that a stable seed crop is maintained throughout the year as a reliable source of food for the red squirrels. Populations of red squirrels would also be more likely to maintain themselves, and expand into new populations, if efforts were undertaken to connect areas of suitable habitat, allowing the migration of red squirrels to more easily occur. The connection of areas of suitable habitat would also benefit other species of animal, and the increased prevalence of conifer forests and plantations could result in a greater diversity of habitats and eco-systems within the United Kingdom. However, if the conifer forests and plantations replace other habitats, there could be a potential loss of productivity, biodiversity and carbon storage, particularly in plantations, which may prioritise the growth of economically profitable species of trees over ecological well-being; this method may also be difficult to implement for financial or logistic reasons. Populations of red squirrels could be bolstered or created by reintroduction, and reintroduction has historically been performed successfully, with the majority of red squirrels within the United Kingdom belonging to a Scandinavian haplotype. Reintroduction has been successful in Anglesey, contributing to the large increase in the number of red squirrels, from forty to seven hundred individuals, there, and several reserves for red squirrels exist in the United Kingdom. However, reintroduction is not always successful; a 1984 project, which involved the release of ten, young red squirrels into Regent’s Park ended in failure, and a similar project in Thetford Forest, which involved the release of twenty-three individuals was shut down in 2001 after a similar lack of success. In 1993, a population of fourteen individual red squirrels was reintroduced onto Furzey Island, but none of the individuals survived for longer than four months, with half of the individuals being eaten or cached by predators. A dissection of the recovered carcasses revealed that the individuals experienced extreme stress and had lost weight, with none of the females showing any evidence of reproductive activity or being at a sufficient weight to enter oestrus. Tracking data regarding the population indicated that they were potentially adversely affected by interference competition from grey squirrels, with the ranges of individual red squirrels overlapping less with those of grey squirrels than those of other red squirrels. As a result, reintroduction may be opposed as the result of the potential suffering that reintroduction could inadvertently inflict upon individual red squirrels. In addition, reintroduction could result in a loss of genetic biodiversity as European haplotypes could potentially become more prominent than endemic haplotypes, which could eventually be entirely replaced, within the populations of red squirrels.

Immunocontraception and surgical sterilisation have been suggested as a more humane alternative to culling, as they would cause individual grey squirrels to become infertile, or ‘sterile’, and , if successful, result in a gradual decrease in the number of grey squirrels within a population without killing, or injuring, individual grey squirrels. These techniques are also advantageous as sterilised grey squirrels would, without contributing to the direct reproduction of the population, continue to survive and maintain their territories, preventing the increased rate of immigration and the increased rate of the production of offspring, which are commonly incurred by culling; in addition, research indicates that immunocontraception would have no significant effect on the behaviours of grey squirrels. However, surgical sterilisation may be opposed for moral reasons, as it requires the trapping of, and performance of surgery upon, individual grey squirrels, who may suffer from stress, injuries, and exposure during the process. The potential efficacy of both techniques is disputed as the result of the fact that they would require around 90% of a population to be sterilised in order to result in a significant decrease in the number of individuals within that population, which would be especially difficult to achieve via surgical sterilisation as surgical sterilisation requires the direct capture of individuals. The use of immunocontraceptives, which could be delivered via bait or a vectored, viral mechanism, is opposed by some as it could potentially affect other species and their populations in an adverse manner if the immunocontraceptives are unintentionally delivered to members of those population, and some people argue that the use of immunocontraceptives against grey squirrels may set an undesirable precedent for their use against people. Size-limiting traps and hoppers could be used to prevent larger animals from consuming baited immunocontraceptives, but similarly sized animals would remain at risk, and trapped individuals could suffer as the result of stress and exposure.

It has been suggested that conservation efforts regarding the populations of red squirrels on the mainland of the United Kingdom should cease, and that, instead, populations should be maintained on, and introduced to, isolated islands with no presence of grey squirrels, which could otherwise compete with the introduced red squirrels. This would allow populations of red squirrels to exist without the need to cull grey squirrels, but would represent a potential cultural and aesthetic losses to the people living on the mainland on the United Kingdom, and the potential loss of an unknown ecological function, as the result of the loss of the populations of red squirrels, there. However, conservation efforts do not necessarily have to be ceased in every location on the mainland, and they could be continued in specific locations where doing so would be beneficial. Mull is one of several islands, which have no presence of grey squirrels, near Scotland that possess suitable woodland for the introduction of red squirrels, and there is evidence for the success of this method; red squirrels were introduced to the Isle of Arran, and an examination of 21 live squirrels, as well as 16 dead squirrels, that belonged to the population on the Isle of Arran found the examined individuals to be relatively healthy, to show few signs of any disease, and to show no evidence of being infected by the squirrelpox virus. Any population of introduced red squirrels may still need to be monitored and protected from the squirrelpox virus, as the virus is likely transmitted by other vectors than grey squirrels, and, therefore, the absence of grey squirrels does not necessarily signify the absence of the squirrelpox virus. The introduced populations of red squirrels may also have the potential of becoming an invasive species on the islands where they are introduced because the local eco-systems may not be adapted to control the populations and effects of the red squirrels, resulting in damage to the biodiversity and eco-system services within such islands, and because they may incur environmental and ecological damage by stripping the bark of trees.

Conclusion.

Initially, I had planned to write a more extensive section in order to share my own perspective, but I ultimately decided against doing so in order to ensure that the length of this article was not overly extensive, in order to prevent my planning for such a section from creating excessive, unconscious biases within the other sections of this article, and in order to ensure that I did not unintentionally create the illusion that my perspective was the most important or most informed perspective, that my perspective was necessarily correct or flawless, or that I was attempting to unfairly favour my own perspective. In the following paragraph, I shall, instead, provide a very brief summary of my own perspective, as I do wish to share it with others in case it might be of benefit to them, and so that they can suggest any improvements that I should or could make to it:

Due to a perceived lack of efficacy and personally undesirable infliction of suffering, I do not believe that the culling of grey squirrels is justified as I also do not believe that grey squirrels have a significant adverse effect, or adverse accumulation of effects, within the United Kingdom, where they, as a result, do not merit the title of ‘invasive species’. In addition, I do not believe that, even if it was far more extensive than it is claimed to be, the economic damages would justify the culling of any sentient species. I am not necessarily opposed to the introduction and reintroduction of pine martens, but I believe that they should not be introduced with the sole intention of controlling populations of grey squirrels, and I believe that research should be performed in order to ascertain that the benefits of the introduction of the pine martens could possibly justify the increased suffering of the animals, which would be incurred by the predation and presence of the pine martens. I think that the development of a vaccination against squirrelpox, the increased prevalence and size of conifer forests, but not conifer plantations that could potentially prioritise profitability over ecological well-being, the connection of fragmented habitats and the introduction of red squirrels to islands without a presence of grey squirrels, would be a better investment of the extensive funding that would be required to, or is otherwise provided to, the culling of grey squirrels, as these measures would better ensure the future security of the presence of red squirrels within the United Kingdom, and could potentially provide other ecological benefits. I believe that the use of immunocontraception may be appropriate to suppress populations of grey squirrels in specific circumstances, but I do not believe that it would be an effective method of controlling the national population; the immunocontraceptives would need to be delivered carefully in order to prevent their unintentional delivery in other circumstances. Despite the lack of research regarding its efficacy in controlling the spread and transmission of squirrelpox, the superior management of feeding stations should be, in my opinion, implemented as the losses of doing so are not particularly costly and are greatly outweighed by the potential benefits of doing so. I believe that we should actively work to ensure that eco-systems provide the greatest possible benefits, but any changes must be implemented with extreme caution and after the performance of prior research, and I believe that actively considering and promoting the well-being of sentient individuals would have many benefits to our society, although I am also of the opinion that we should be careful not to inadvertently inflict greater sufferings by prioritising the well-being of individuals over the well-being of the systems that they influence, and are influenced by. In order to ensure that our perspectives and decisions regarding the culling of grey squirrels are better informed, I would suggest that research is performed regarding the ecological function of grey squirrels within the United Kingdom, and how that function differs from the function of the species within North America, alongside research with the intention of ascertaining the existence of any as-of-yet unknown ecological functions of red squirrels within the United Kingdom; this would allow us to better understand the ecological benefits and problems that are caused by the replacement of populations of red squirrels by populations of grey squirrels.

You have my gratitude for reading this article, as well as my hopes that doing so was a beneficial experience for you, and that you may feel more informed regarding the culling of grey squirrels. I am, despite my assurances to you that I have striven to both avoid providing any misinformation or deceit and to mitigate the effects of any inappropriate biases, not an infallible source of information, and I encourage you to pursue your own, further research regarding this subject in order to ensure that you have a greater, more diverse and informed understanding regarding this subject. You also have my gratitude for any criticisms or feed-back that you provided to me regarding this article, and I would be very much interested to learn about your own perspectives regarding the culling of grey squirrels and if this article, or other items of information, influenced any changes to such perspectives.

Photo by Mike Bird on Pexels.com

Sources and Resources:

https://en.wikipedia.org/wiki/Eastern_gray_squirrel A ‘Wikipedia’ Article regarding Grey Squirrels.

https://en.wikipedia.org/wiki/Red_squirrel A ‘Wikipedia’ Article regarding Red Squirrels.

https://www.forestry.gov.uk/pdf/fcpn004.pdf/$FILE/fcpn004.pdf Information regarding the reasons and methods used for the culling of grey squirrels.

http://pmep.cce.cornell.edu/profiles/extoxnet/pyrethrins-ziram/warfarin-ext.html Information regarding warfarin.

https://www.cla.org.uk/about-cla/our-work/working-you/grey-squirrels-and-warfarin# Information regarding the ban of warfarin.

https://en.wikipedia.org/wiki/European_pine_marten A ‘Wikipedia’ Article regarding Pine Martens.

https://link.springer.com/article/10.1007/s10531-014-0632-7 https://royalsocietypublishing.org/doi/full/10.1098/rspb.2017.2603 Two Studies regarding the reducing effect of the presence of Pine Marten populations on that of grey squirrel populations. https://www.the-ies.org/analysis/alien-versus-predator An interview with the author of one of the studies.

https://www.theguardian.com/environment/2018/mar/07/return-of-pine-martens-could-save-britains-red-squirrels-say-scientists An Article regarding the use of Pine Martens to control grey squirrel populations.

https://www.britishredsquirrel.org/grey-squirrels/pine-martin/ Information regarding the use of Pine Martens to control grey squirrel populations.

https://pine-marten-recovery-project.org.uk/ The ‘Pine Marten Recovery Project’.

https://www.gloucestershirewildlifetrust.co.uk/pine-marten-feasibility-study-summary The Feasibility study by the ‘Gloucester Wildlife Trust’ regarding the reintroduction of pine martens to the Forest of Dean.

https://www.gloucestershirewildlifetrust.co.uk/sites/default/files/2018-05/Pine%20martens%20in%20the%20FoD%20Stakeholder%20and%20public%20attitudes.pdf Public Attitudes regarding the reintroduction of Pine Martens within the Forest of Dean.

https://www.thejournal.ie/pine-martens-attacking-2949590-Aug2016/ A newspaper article regarding the claimed threat of pine martens to children.

https://www.imperial.ac.uk/news/170448/dont-blame-grey-squirrels-their-british/ Article discussing how Grey Squirrels were introduced on multiple occasions into the United Kingdom, and are not the result of a single, expanding population.

https://www.woodlands.co.uk/blog/flora-and-fauna/how-did-the-grey-squirrel-arrive-in-the-uk/ https://www.bbc.co.uk/news/uk-england-beds-bucks-herts-35417747 Articles regarding the History of the introduction of Grey Squirrels into the United Kingdom.

https://www.animalaid.org.uk/wp-content/uploads/2017/02/historygreysquirrels.pdf A Publication discussing the History of the culling of squirrels in the United Kingdom.

https://www.bbc.co.uk/news/magazine-34603394 An Article discussing the elimination of grey squirrels from Anglesey.

http://www.redsquirrels.info/education/red-squirrel-conservation/ Information regarding the conservation of red squirrels.

https://en.wikipedia.org/wiki/Eastern_grey_squirrels_in_Europe A ‘Wikipedia’ article regarding Grey Squirrels and their presence and introduction into Europe.

https://www.bangor.ac.uk/research/news/there-are-no-two-ways-about-it-grey-squirrels-are-bad-for-the-british-countryside-31729 An Article that describes and provides evidence of the harmful effects of Grey Squirrels, advocating in favour of the cull.

https://www.woodlandtrust.org.uk/mediafile/100258230/Squirrel-position-statement.pdf The Position of the ‘Woodland Trust’ regarding Grey Squirrels.

http://i-csrs.com/effect-squirrels-birds https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0109397#s4 https://www.researchgate.net/publication/225446103_Potential_impact_of_grey_squirrels_Sciurus_carolinensis_on_woodland_bird_populations_in_England http://news.cision.com/kendalls/r/predation-of-woodland-songbirds–grey-squirrels-have-a-case-to-answer,c9224977 Research and studies regarding the effects of grey squirrels on bird populations.

https://www.sciencedirect.com/science/article/pii/S0378112716300421 A research paper regarding the stripping of bark by grey squirrels.

https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2656.2004.00791.x A Study regarding the competition between grey and red squirrels.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3914897/ https://link.springer.com/article/10.1007%2Fs00436-015-4466-3Studies that indicate that Grey Squirrels may increase the prevalence of parasitic infections in Red Squirrel populations.

https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2656.12853 https://www.britishecologicalsociety.org/red-squirrel-stress/ A study evidencing that Grey Squirrels induce stress amongst Red Squirrel populations, and an article, which discusses the study.

https://www.theguardian.com/environment/2008/jun/07/red.squirrel An Article discussing red squirrels.

https://www.wildlifeonline.me.uk/questions/answer/what-is-squirrel-pox-when-did-it-arrive-in-britain An Article discussing the History, Effects and Spread of Squirrelpox in the UK, as well as the research surrounding it.

http://i-csrs.com/ The ‘Interactive Centre for Scientific Research about Squirrels’, or ‘ICSRS’. I have used this group as a source of information and opinions, particularly when attempting to find opposing views to the arguments in favour of the culling of grey squirrels, as it seems to be well-researched and to use reliable sources of information itself; some of its interpretations of research seem to be biased, or to ignore certain results, however.

http://www.grey-squirrel.org.uk/victimising_grey_squirrels_2.pdf A Publication in opposition to the culling of grey squirrels.

https://www.urbansquirrels.co.uk/the-myth-of-the-evil-grey-squirrel/ An Article defending Grey Squirrels.

http://theconversation.com/in-defence-of-the-grey-squirrel-britains-most-unpopular-invader-73983 An article in opposition to the culling of grey squirrels.

http://i-csrs.com/squirrels-and-forest-regeneration Information regarding the role of squirrels in forest regeneration.

https://watermark.silverchair.com/77-2-305.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAj8wggI7BgkqhkiG9w0BBwagggIsMIICKAIBADCCAiEGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMY_NMVqU6Rxd1m1eTAgEQgIIB8mOgQq0uyuh-CE7L_avTES4_fgRUqNYivPIQDMo1ETvcK8gkI8t6kgBqC5_sM9MjMZTvq4YKbxRPZ0OVxR-9XY2q7VkRxVOuiZSSrhvYtrskjShly2_lCX9FqdI6dT-h0jnl4dLcFeoXvpWtPZG1cwnE5-yV5-T0zkrgmIy7ifhYZipvU0HTcXBZ-nChLgG7cSRR8kjFIuNbFXA0CCZrJaMyQe0cWCRgMgujqZLNiwShNbmEzRfwyBpqgmgLN-yEHbK_htVrDGRvZyz0F0NtZS1g3q6X-ax1VVxTL0SWSs6sa7kJEMKhwlcv_FkP-a-W5fJBkVdu4qUKg5w9JBHDNUdr7g5psQLY6822MBmRB2-vZgrqFN4i0ImP8v2u4zLuV7EEldAIwy89Zd3Y2kJ30FXQnbKwUm4rhwcT06fGykk8oXo6NYtsbO6vRN9J3-LtRmCY3RQWrK2Gs3opZY2xYzvx2bfD2-g2Nhxh12H-kZvV_eBoVcTH3-9Hk44w6wKay8ydIzopJFibP4YIVCBEyg0k6yT2YcUfbuvWm1BcjP9M4qspLrPkLOfKMGw8VQB17UOZlcVA7g6R2PrrUJJvzM_hSckm_v8wIgzmxn51p13G1N5-ZXkzZB9xFn8gB4pOGZ-pB4j8zJkCXbFMEgGt7-nY5w https://www.researchgate.net/publication/233697005_Food-hoarding_behavior_of_gray_squirrels_and_North_American_red_squirrels_in_the_central_hardwoods_region_Implications_for_forest_regeneration Two studies regarding the food-hoarding behaviour of grey squirrels.

https://ofnc.ca/programs/fletcher-wildlife-garden Information regarding the Grey Squirrels in the Fletcher Wildlife Garden.

https://www.researchgate.net/publication/225725295_Feeding_and_hoarding_behaviour_of_the_Eurasian_red_squirrelSciurus_vulgaris_during_autumn_in_Hokkaido_Japan A study regarding the food-hoarding behaviour of red squirrels.

https://www.environmentalscience.org/invasive-species http://www.actionbioscience.org/biodiversity/simberloff.html Two Articles that explain, and provide examples, of the harmful effects of invasive species.

https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/09-1301.1 https://www.sciencedaily.com/releases/2010/05/100517111939.htm A Study, and article, which discusses that study, regarding Asian shore crabs in North America.

https://news.nationalgeographic.com/news/2014/07/140724-invasive-species-conservation-biology-extinction-climate-science/ http://blogg.vm.ntnu.no/naturviten/2018/08/27/mark-davis-rethinking-invasive-biology/?lang=en https://ocean.si.edu/ocean-life/plants-algae/rough-reputation-are-invasive-species-all-bad An Opinion-piece, interview and article arguing against the persecution of all non-native species, which suggest that not all non-native species should be considered ‘invasive’, and that we should evaluate the real impact of a species before making any decision regarding its future.

https://www.onekind.scot/wp-content/uploads/0811_grey_squirrel_populations.pdf A report by the University of Bristol regarding the culling of grey squirrels.

https://www.bbc.co.uk/news/uk-wales-46508702 An article regarding an unique genetic haplotype amongst red squirrels in Wales.

https://www.dailypost.co.uk/news/local-news/wales-cracks-down-grey-squirrel-15616929 An Article regarding the control of grey squirrel populations in Wales.

http://publications.naturalengland.org.uk/file/93025 A Paper regarding the potential development of a vaccine against squirrelpox.

https://www.scotsman.com/news/environment/hope-for-scotland-s-red-squirrels-as-researchers-develop-killer-pox-vaccine-1-1365565 An article regarding the development of a vaccine against squirrelpox by Moredun.

http://www.thejournal.co.uk/news/north-east-news/wildlife-ark-trust-charity-red-7583049 An article providing information regarding the development of a vaccine against squirrelpox by Moredun.

https://www.wildlifeonline.me.uk/questions/answer/why-is-the-red-squirrel-declining-in-the-uk-and-what-can-be-done Information regarding the decline of the red squirrels, and potential solutions to this decline.

https://www.independent.co.uk/environment/prince-charles-squirrels-nutella-sterilise-plans-backs-grey-red-a7597481.html An Article regarding the use of immunocontraception techniques to control grey squirrel populations.

https://www.theguardian.com/environment/2017/jun/02/kill-them-the-volunteer-army-plotting-to-wipe-out-britains-grey-squirrels An article discussing the culling of grey squirrels, and the experiences and insights of those involved in, and opposed to, such culling.

https://www.ed.ac.uk/news/2014/squirrels-290114 Information regarding the population of red squirrels on the Isle of Arran.