Cairngorms Connect has an ambitious 200-year vision to restore and enhance natural habitats in the Scottish Highlands. The humble moth has been one of three indicator groups used to date to monitor how species respond to habitat management at different altitudinal ranges. This project will collect data over the next five years, which can then be used as a baseline when these species groups are resurveyed in 10, 50, or even 200 years’ time, to see how restoration efforts have influenced species across the Cairngorms Connect area. This project has been supported greatly by the time and expertise of Cairngorms Connect supporting partner, Butterfly Conservation.
Why use moths an indicator of ecological health? Moths are a highly diverse group, with many species adapted to a specific habitat or larval foodplant, which makes them an excellent candidate for monitoring ecological conditions. The Cairngorms Connect team are using two complementary approaches to monitor macro moth species, which as their name suggests tends to include larger species: a ‘longitudinal’ and a chronosequence’ approach. Longitudinal traps are at fixed points which are sampled annually, being sampled spring, summer & autumn seasons at fixed altitudes of 300m, 500m, 700m, 900m. Chronosequence traps are a larger set of points across the area but are visited only two times during one project year.
A summary of the two approaches can be found below:
|Longitudinal study||Chronosequence study|
|Site monitoring frequency||Every month during June – Sept, every year of project||Twice in one year of project|
|Monitoring site type||Fixed points||Randomly selected, remote|
|Equipment||Robinson 125W mercury vapour moth trap||Heath 15W actinic trap|
|Altitudes measured||300m, 500m, 700m, 900m||Variable|
The scale and remoteness of the Cairngorms Connect area, coupled with the unpredictability of weather means that moth monitoring here is not without its challenges. Cairngorms Connect Monitoring Officer, Ellie, often hikes for several hours with equipment, navigating steep uplands and streams as she goes, camping out overnight and rising at dawn to complete the survey. On occasion she has awoken to frost covering the tent, whilst on warmer mornings she is often ‘greeted’ with swarms of biting midges as she checks the traps. Despite these challenges, the spectacular sunrises and the excitement of opening a trap to see what wild, intricately decorated presents are inside make it all worth it for Ellie.
This year, the success of moth trapping fluctuated with the seasons. The prolonged cold and wet over the spring resulted in lower moth catches than anticipated through May and June, but as the weather improved throughout the summer so did the data – even at higher altitudes. For example, the longitudinal site at 300m found 118 moths of 18 species in the July session compared to 22 moths of 7 species in June. Another July catch at 700m on Glenfeshie found 612 moths in a single night where only a few weeks before, the trap on that site had been empty of macro moths the following morning.
Catching moths at higher altitudes is still a relatively novel practice and so the first few months of the project have involved a lot of adaptive learning to make sure that traps are set up in optimum conditions. For example, the monitoring team have found that adding guide ropes to the outside of traps helps to mitigate the rather unpredictable weather conditions often found up at these higher altitudes.
Setting up moth trapping at project sites in early evening light. Photo credits: Cairngorms Connect.
Over the next five years, these higher altitude areas will transform as montane scrub (particularly birch and willow) is restored to these habitats. In summer 2019 a moth trapping session at Glenfeshie, where a substantial amount of broadleaf planting has recently occurred nearby, found several associated with broadleaf trees – including lesser swallow prominent and coxcomb prominent. This is a promising early sign given the specialist conditions required for these species to be able to breed and feed in the area. With Cairngorms Connect on track to transform the 60,000 ha of land within its project area, it is exciting to think which new species will show up over the coming years.