In a bid to unravel the mystery behind the decline of native red squirrels across the UK, a recent study has delved into the intricate world of gut bacteria, shedding light on how these tiny organisms might be influencing the competition between red and grey squirrel species.
Led by a team of researchers, the study compared the gut bacteria of red and grey squirrels, aiming to elucidate the factors contributing to the displacement of red squirrels by their grey counterparts and the damage inflicted by grey squirrels on woodlands.
Grey squirrels, introduced to the UK in the late 19th and early 20th centuries, have since outcompeted red squirrels in many regions, posing a significant threat to the native species. One key factor driving this competition is the presence of a virus called “squirrelpox” carried by grey squirrels, which is lethal to red squirrels.
The study revealed that grey squirrels, being larger in size, have a competitive advantage over red squirrels in accessing food and habitat. Their ability to digest acorns, a common food source, more efficiently than red squirrels gives them an edge in resource competition.
Moreover, grey squirrels exhibit destructive behaviour by stripping bark from deciduous trees, causing damage that can lead to fungal infections and decrease timber quality, incurring an estimated annual cost of £37 million. The research highlighted how grey squirrels selectively target trees with the highest sap volume, potentially driven by a need for specific micro-nutrients.
By analysing the gut bacteria of both species, researchers made several intriguing discoveries. Grey squirrels were found to harbour a significantly higher diversity of gut bacteria compared to red squirrels, potentially enabling them to access a broader range of resources.
Furthermore, the presence of a bacteria called “oxalobacter” in grey squirrel guts suggests they may possess the ability to digest calcium found in tree bark, a crucial nutrient for lactating and growing animals. This finding may explain the timing of bark-stripping behaviour, which coincides with the period of increased calcium availability in trees.
The study also highlighted the role of gut microbiota in disease susceptibility, with grey squirrels carrying adenovirus without exhibiting symptoms, unlike red squirrels. This underscores the complexity of interactions between gut bacteria and host health.
While the research focused on red and grey squirrels from north Wales, the implications extend beyond regional boundaries. Future studies mapping gut microbiota in other European populations will further enhance our understanding of squirrel competition dynamics.
In conclusion, the study offers valuable insights into the ecological factors driving the decline of red squirrels and the invasive success of grey squirrels. By uncovering the role of gut bacteria in mediating competition and disease susceptibility, it paves the way for targeted conservation efforts and informed management strategies to safeguard native species against invasive threats.
