Butterflies in Scotland

At least 35 species of butterfly are known to consistently breed in Scotland (Butterfy Conservation Scotland, 2020). Butterfly species are split into two categories depending on their preferred habitats: Generalist and Specialist. Generalist species are able to live in a wide variety of habitats, and include species such as peacock (Aglais io) and orange-tip (Anthocharis cardamines) butterflies (NatureScot, 2016; NatureScot, 2023 b). Specialist species require specific habitat types, and so are more vulnerable to habitat loss (JNCC, 2023). For example, grayling (Hipparchia semele) are a specialist butterfly species (Fig. 1)(NatureScot, 2023 c).

Recent Trends & Distribution:
Overall, Scottish pollinator numbers have been decreasing since the 1980s, dropping by at least a half as of 2017 (Scottish Government, 2017). Butterfly numbers on the other hand have seen more success, rising overall by 35% in the same four decades (NatureScot, 2023 a). It is important to note how these patterns vary between butterfly species. Generalist species have recorded a 47% increase between 1979 and 2022, while specialist species decreased by 67% between 1979 and 2014 (Fig. 3)(NatureScot, 2016; NatureScot, 2023 b).  

The picture of the wider UK is not overly positive, with JNCC (2023) reporting either deteriorating or consistent status in UK butterfly species numbers, with no overall population recovery observed. 

Butterflies on the East Grampian Coast: 
Three key butterfly species found on the East Grampian Coast are grayling, northern brown argus, and dark green fritillary. Other species which can be found along the coast include orange-tip, peacock, and small pearl-bordered fritillary (Boloria selene). Small blue (Cupido minimus) is a coastal butterfly species which is currently absent from the East Grampian coast, however it can be found further down the east coast into Angus, or along the north-east coast around Portsoy.

Grayling
Grayling are a widespread coastal species around the UK. Key caterpillar foodplants include sheep's-fescue (Festuca ovina), red fescue (F. rubra), bristle bent (Agrostis curtisii), and early hair-grass (Aira praecox). The species has seen huge declines nationally, with a 72% reducation in abundance and 92% reduction in distribution between 1976-2019. Grayling are an Endangered species on the GB Red List (Butterfly Conservation, n.d. a).
   
Northern Brown Argus 
Northern brown argus (Aricia artaxerxes) (Fig. 2) occurs largely in Scotland and Northern England and is both a coastal and upland species. Along the East Grampian coast there are colonies between Cove and Stonehaven. Key caterpillar foodplants include common rock-rose (Helianthemum nummularium). The species has seen declines nationally, with a 57% reducation in abundance and 56% reduction in distribution between 1976-2019. Northern brown argus are a Vulnerable species on the GB Red List (Butterfly Conservation, n.d. b).
   
Dark Green Fritillary
Dark green fritillary (Speyeria aglaja) is a widely distributed butterfly species across the UK, with some strong colonies along the East Grampian Coast. Key caterpillar foodplants include common dog-violet (Viola riviniana), hairy violet (V. hirta), and marsh violet (V. palustris). The species has seen a 214% increase in abundance but a 40% reduction in distribution between 1976-2019. Dark green fritillary are a Near Threatened species on the GB Red List (Butterfly Conservation, n.d. c).

What benefits do butterflies bring?
While not technically classed as vital pollinators (the category of bees for example), the presence of butterflies is necessary to support vital pollinator species (NatureScot, 2023b). They play a multitude of crucial roles in Scotland’s ecosystems, from acting as prey for native birds and bats, to controllering numbers of smalller insects.  They are also highly valuable in scientific research, and can be beneficial to communities and positive mental health outcomes by getting people engaged with the outdoors (Butterfly Conservation, 2021). 

Impacts on Butterfly Populations:
Climate change is having both positive and negative impacts on butterfly populations, and the influence it is having is species dependent. Some generalist species are benefitting from global rising temperatures and are expanding in range and distribution (NatureScot, 2016). However, warming temperatures are shifting plant seasonality which influences on butterfly breeding and feeding cycles. Increasing frequency of extreme weather events is also impacting butterfly populations (NatureScot, 2023b).

Habitat loss and fragmentation is a large impact on butterfly populations, particularly from intensive agricultural activities,  distrupting breeding and feeding opportunities. This break-up of habitat can cause butterfly populations to become isolated and unable to bounce back when population numbers are reduced (NatureScot, 2023b).

Conservation Efforts:
Currently, Scotland is a stronghold for various species that are threatened in other parts of the country (Butterfly Conservation, 2018). With climate change and human caused landscape degredation, the risks all butterfly species face will continue to rise without concerted efforts towards conservation.There are a number of butterfly conservation projects and groups are in action across the country. Some examples include:

• Pollinator Strategy for Scotland 2017-2027: A collaborative project by Scottish Natural Hertiage the Scottish Government, and many other groups, aiming to protect and promote pollinators in Scotland (NatureScot, 2020 a). 
• Butterfly Monitoring Scheme (UKMBS): A long-running project, using community involvement to monitor butterfly numbers since 1976 (UKBMS, n.d.)
• Species on the Edge: A project by NatureScot to protect highly threatened species and habitats in Scotland. Butterflies protected by the project include the Marsh Fritillary, the Northern Brown Argus, and the Small Blue Butterfly, as well as various moth species (NatureScot, 2020 b).