Blog by Ellie Dimambro-Denson, Monitoring Officer, Cairngorms Connect.
With funding from the Endangered Landscape Programme, Cairngorms Connect has an ambitious 200-year vision to restore and enhance natural habitats and processes in the Scottish Highlands. Monitoring both the habitats and species within the Cairngorms Connect area will play an integral role throughout the life cycle of the project. The main focus of monitoring to date has been within the ‘Species Indicator Project’, using moths as one of three indicator groups trapped at different altitudinal ranges to help monitor how species are responding to the habitat management undertaken.
By collecting baseline data over the next five years, we will be able to resurvey these species groups in 10, 50, or even 200 years’ time, to see how the restoration work has 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.
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. We are using two complementary approaches to monitor macro moth species across the Cairngorms Connect area during the next five years. The first is a longitudinal (i.e. sites are monitored every year) that uses a powerful 125W mercury vapour trap at four sites at 300m, 500m, 700m and 900m altitude, with sites surveyed monthly from June – September, for five years. The second is a chronosequence approach (i.e. using spatial variation in habitat conditions as a proxy for time since restoration, when taking other factors such as altitude into account) for which we are using a more portable 15W actinic heath trap to collect data from more remote, randomly-selected sites throughout the Cairngorms Connect area over the next five years, visited twice in a single year.
Photo: Heath moth trapping at a ‘chronosequence’ site at 750m altitude at Abernethy (RSPB Scotland) (left) Robinson moth trapping at a ‘longitudinal’ at 900m altitude in Glenfeshie (Wildland Ltd) (right)
The success of moth trapping has 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 any macro moths the following morning.
Photo: Coxcomb prominent on a recording form
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.
Over the next five years, these higher altitude areas will transform as montane scrub (particularly birch and willow) is restored to these habitats. A recent 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 (which feeds on birch species) and coxcomb prominent (which feeds on a variety of broadleaf trees). This is of particular note as for these species to be present in an area, habitat conditions need to have the ability to support them, allowing the right conditions to feed and reproduce. Prior to the broadleaf planting, it is unlikely the habitat would have been able to support these species and so their presence is a promising early sign of the ecological restoration of the habitat and will be interesting to track through the duration of the project.
Photo: Wing scales of a pine beauty moth, viewed under a light microscope
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, and Project Scientist, Pip, often hike for several hours with equipment, navigating alone across steep uplands and streams, camping out overnight and rising at dawn to complete the survey. On occasion they have awoken to frost covering the tent, whilst on warmer mornings are often greeted with swarms of biting midges as they check the traps. But moth trapping in the hills can reveal much beauty – spectacular sunrises, intricate patterns on moth wings looking mosaic like under the hand lens, not to mention the excitement and anticipation of opening the trap to reveal what may be waiting inside. With Cairngorms Connect on track to transform the 60,000 ha of land within its project, it will be fascinating to see what new species may show up over the coming years.
Photo: Evening light on Coire Garbhlach, on route to a moth trapping site in Glenfeshie (Wildland Ltd.) (left) Walk in to a ‘Chronosequence’ site near Loch Morlich (Forestry and Land Scotland) in the evening (right)
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