Literature Review: Pine Marten Recovery: A Tool for Biological Invasive Species Control and Red Squirrel Conservation? 

Themes Explored: 

• Observed population changes of red and grey squirrel in areas of pine marten recovery. 

• Dietary analysis of pine martens. 

• Pine martens as a novel predator to grey squirrel, which do not have arboreal predators in their natural environment. 

• Effects on resource and disease mediated competition between red and grey squirrels, driven by pine marten recovery. 

• Public opinions on pine marten as a form of grey squirrel control. 

Key Findings:  

Pine marten recovery likely contributes to grey squirrel control efforts, but as part of a wider strategy and evaluated on a case-by-case basis, where different ecological dynamics are at play. There is evidence of higher quantities of grey squirrel in pine marten diet in areas where both squirrel species occur. As well as multiple instances of red squirrels clearly demonstrating more cautious behavior when exposed to pine marten scent versus grey squirrel. It can be inferred that this suppresses both resource and disease-mediated competition between red and grey squirrels, likely having long term benefits for red squirrels. 

Empirical Paper: Red Squirrel in Mid Wales: A Review of Long-term Monitoring Data and Recommendations for Future Conservation Management 

Themes Explored: 

• Outcomes from long term monitoring, looking at frequency of sightings of pine marten, grey squirrel and red squirrel from within the MWRSP focal area and buffer zone. Collected from trapping data, trail cameras and sightings. 

• Limitations of data collection, in particular lack of absence data and issues arising from working across a large and remote area. 

• Recommendations for future monitoring methods and identifying key knowledge gaps for future research. 

Key Findings: 

Whilst no statistical significance could be identified on the effects of pine marten presence on red and grey squirrel within the MWRSP area, trends did indicate potential causation between increased frequency of pine marten sightings in 2021 and a decrease in frequency of grey and red squirrel sightings. However, due to the lack of absence data and general inconsistencies of data collection, this is tenuous at best. This highlighted the need for more robust approaches to long-term monitoring. Additionally, prioritisation of gaining understanding of the genetic health of the population was highlighted as a key action moving forward. Given the complexities of the area and habitat, gaining conclusive population numbers will be difficult, but genetic analysis will still provide a useful snapshot of the health and long-term viability of this population of red squirrels.