Grey or red?

Ask anyone living in the UK what colour a squirrel is and it’s likely they’s say grey, that’s grey with an ‘e’ not an ‘a’ like in America, but the grey squirrel isn not native to these lands, it is another invader.

Grey squirrels are so ubiquitous in the UK that we’ve all but forgotten that our nativce squirrels are red and you might be thinking so, what, one is re4d one is gray, they’re both the same right? Sadly no.

The Wildlife Trusts estimate there to be around 140,000 red squirrels and a whopping 2.5 million grey squirrels living in the UK.

How did they get here?

The grey squirrel (Sciurus carolinensis) is native to the oak-hickory woodlands of the eastern United States, where it coexists with the American red squirrel (Tamiasciurus douglasi). Despite its striking resemblance to S. vulgaris, the American red squirrel is only distantly related.

Historically, grey squirrels have been introduced to parks and forests across mainland UK. Records of these introductions, primarily from private or pet collections, date back to 1828 when one was reportedly released near Denbighshire in north Wales. The first verifiable record, however, is from 1876. Victorian banker Thomas V. Brocklehurst brought a pair of grey squirrels back from a business trip to America and released them into Henbury Park near Macclesfield in Cheshire after their appeal as pets diminished. This act seems to have started a trend, similar to his relative Sir Henry C. Brocklehurst's release of red-necked wallabies (Macropus rufogriseus) into Staffordshire during the mid-1930s. Releases of grey squirrels continued for the next 50 years.

In "The Naturalized Animals of Britain and Ireland," Christopher Lever provides a comprehensive account of grey squirrel introductions. He notes that:

“Between 1902 and 1929 (the year of the last recorded introduction), a veritable wave of introductions took place in many localities, including Regent’s Park, London; Berkshire; Northamptonshire; Oxfordshire; Staffordshire; Devon; Warwickshire; Nottinghamshire; Suffolk and Hampshire (Bournemouth). From some of these centres, grey squirrels spread into Gloucestershire and eastern Wiltshire. The stock for most of the introductions came either directly from the United States or from Woburn.”

Why are these grey squirrels a problem?

The red squirrel (Sciurus vulgaris) does not cause the same problems as the grey squirrel (Sciurus carolinensis) in the UK due to several key differences in their behavior, ecology, and impact on the environment.

As a native species, red squirrels have coexisted with the local ecosystems for thousands of years. This long-term presence has allowed them to establish balanced relationships with other species and their environment. Over time, red squirrels have coevolved with local plant and animal species, leading to a stable ecological equilibrium. Their feeding habits, nesting preferences, and other behaviours have adapted to the native woodland environments without causing significant disruption.

Red squirrels primarily feed on tree seeds, nuts, fungi, and fruits. Their foraging behaviour tends to be less destructive than that of grey squirrels. Unlike grey squirrels, they do not strip bark from trees extensively, which means they cause less damage to forestry. Additionally, red squirrels build nests, or dreys, in tree canopies using materials like twigs, leaves, and moss. This behaviour does not significantly impact the health of the trees or the surrounding habitat.

One major advantage of red squirrels is their lack of disease transmission. Unlike grey squirrels, red squirrels do not carry the squirrelpox virus, which is deadly to other squirrels. This means their presence does not pose a health threat to grey squirrels or other wildlife through disease transmission.

In terms of population dynamics, red squirrels typically have a lower reproductive rate compared to grey squirrels. This means their populations grow more slowly, reducing the likelihood of overpopulation and the associated environmental pressures. Additionally, red squirrels are generally less aggressive in their competition for resources. They do not outcompete other species to the same extent as grey squirrels, allowing for a more balanced coexistence with other woodland creatures.

Red squirrels also have a minimal impact on forestry and agriculture. They do not engage in extensive bark stripping, a behaviour commonly seen in grey squirrels, resulting in minimal damage to trees and forestry resources. Furthermore, red squirrels have a limited impact on agricultural activities compared to grey squirrels. They do not significantly raid crops or gardens, reducing their negative impact on human economic activities.

Conservation efforts for red squirrels are robust in the UK. Red squirrels are a protected species, with significant efforts aimed at preserving and enhancing their populations. These efforts include habitat restoration, disease management, and grey squirrel control. There is considerable public support for red squirrel conservation, which helps drive efforts to maintain and restore their populations. This support includes volunteer programs, education campaigns, and funding for conservation projects.

In summary, red squirrels do not cause the same problems as grey squirrels in the UK due to their native status, balanced ecological relationships, less destructive behavior, lower reproductive rates, and minimal disease transmission. They are an integral part of the UK's natural heritage and biodiversity, and conservation efforts focus on protecting and enhancing their populations rather than controlling them as pests.

Mutual co-evolution

The mutualism between red squirrels and native trees in the UK is a prime example of coevolution starting about 10,000 years ago after the last ice age. Over millennia, both red squirrels and native trees have evolved traits that enhance their mutualistic relationship. For example, red squirrels have developed strong incisors for cracking open hard nuts and seeds, while some tree species have evolved seed characteristics that encourage caching behaviour. This coevolution has led to a finely tuned balance where both species benefit from their interactions.

Red squirrels play a crucial role in seed dispersal, which is vital for the regeneration of many native tree species. They gather seeds, nuts, and other tree-produced foods and store them in caches for later use. Not all of these cached seeds are retrieved and consumed, it has been suggested by some researchers that the squirrels ‘forget’ where they have hidden as much as 80% of the nuts they gather and usually only find their own stashes by accident rather than memory, it is possible that this ‘memory problem’ is actually to mutual advantage of both the squirrels and the trees as the nuts not found have the potential to grow into new trees away from the parent.

Native trees, such as oaks (Quercus species), Scots pine (Pinus sylvestris), and beech (Fagus sylvatica), provide a significant portion of the red squirrel's diet. These trees produce seeds and nuts that are high in nutritional value, supporting the health and reproductive success of red squirrels. The availability of these food sources is essential for the survival of red squirrel populations, especially during winter months when other food is scarce.

The relationship between red squirrels and trees contributes to the overall health of woodland ecosystems. By dispersing seeds, red squirrels help maintain tree species diversity and forest structure. This diversity is important for ecosystem stability, resilience, and the provision of habitat for other wildlife species. Trees benefit from the reduced competition and increased chances of seedling establishment, while squirrels benefit from the consistent food supply.

Trees and red squirrels have an evolved mutual dependency, a relationship that has developed over 10,000 years

Ethical considerations of this unintended introduction

The story of the grey and red squirrels in the UK presents some rich ethical questions about our responsibility towards other species, the dilemmas of conservation, the value of different species, and the morality of human intervention. It challenges us to reflect deeply on our role within the natural world and consider the complex interplay of ethical principles that guide our actions. This situation offers an opportunity for humanity to reclaim its role as a beneficial keystone species within nature.

Philosophically, the introduction and subsequent impact of grey squirrels force us to confront our responsibilities. As the dominant species, humans have the power to shape ecosystems, and with this power comes the responsibility to do so in ways that benefit the broader ecological community. Our actions must strive to maintain or restore ecological balance, acknowledging the intrinsic value of all species while prioritising the health and integrity of ecosystems.

To move forward, we must adopt a holistic approach to conservation, one that integrates scientific understanding with ethical reflection. This means recognising that our interventions should not only mitigate past mistakes but also foster resilient ecosystems. One such intervention is the controlled culling of grey squirrels to protect the endangered red squirrels and preserve biodiversity. This action, while ethically complex, can be justified through a consequentialist lens, aiming to achieve the greatest good for the ecosystem as a whole.

In addition to specific interventions, broader strategies are essential. Habitat restoration projects can create environments where red squirrels and other native species can thrive. Public education campaigns can raise awareness about the importance of native species and the impacts of invasive ones. Support for scientific research into non-lethal control methods, such as immunocontraception for grey squirrels, can offer more humane and sustainable solutions.

Engaging in these actions helps us reclaim our role as a beneficial keystone species. By acting as stewards of the environment, we can facilitate positive interactions among species, promote biodiversity, and ensure the long-term health of ecosystems. This requires a commitment to ongoing learning, ethical consideration, and adaptive management practices.

The interplay of ethical principles in this context—balancing individual species' intrinsic value with ecosystem health—demands a nuanced approach. We must be willing to make difficult decisions, guided by both scientific evidence and a compassionate understanding of our interconnectedness with all life forms. By doing so, we honour our responsibility to nature and contribute to a more balanced and harmonious world.

The grey and red squirrel situation in the UK serves as a poignant case study for humanity's potential to act as a positive keystone species. Through thoughtful intervention, habitat restoration, public education, and innovative research, we can address ecological imbalances and foster a healthier relationship with the natural world. This path forward requires integrating scientific knowledge with philosophical reflection, ensuring that our actions benefit the entire ecological community.