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SCOTTISH NATURAL HERITAGE SCIENTIFIC ADVISORY COMMITTEE SNH TERRESTRIAL INVERTEBRATE STRATEGY

Purpose

1. This paper and the Annex outline an initial draft SNH conservation strategy for Scotland’s terrestrial invertebrates. The approach focuses on species of conservation concern for which viable, relevant and evidence-based measures are available. The level of ambition and proposed actions area provisional subject to wider consultation. This proposal is contribution to the Scottish Biodiversity Strategy.

Action

2. The Scientific Advisory Committee is asked to:

i) Review the rationale of this strategy; and ii) Endorse approach taken.

Preparation

3. This paper was prepared by Athayde Tonhasca, with input from Mairi Cole, Iain MacGowan and Des Thompson. It also benefited from discussions with representatives of Buglife (The Invertebrate Conservation Trust), RSPB, Bumblebee Conservation Trust, Cairngorms National Park Authority, RSPB, James Hutton Institute, British Arachnological Society, Butterfly Conservation Scotland, British Dragonfly Society and Scotland's Rural College. The paper is sponsored by Sally Thomas.

Background 4. Scotland is the home of at least 24,000 invertebrate species (more than 12 times

the number of all UK bird, mammal and vascular plant species combined). Many of these, particularly in montane, upland and boreal habitats, have become rare or extinct elsewhere in the UK or Europe (Rotheray & MacGowan, 1996; Macadam & Rotheray, 2009). Habitat loss and fragmentation, land conversion, agricultural intensification, landscape homogenisation, urbanization, pesticides and pollution have been identified as the main threats to invertebrate species in Scotland and elsewhere (Macadam & Rotheray, 2009; Aspinall et al., 2011). Recently, climate change has been recognised as one of the main long-term threats to biodiversity. There is limited evidence that climate changes are causing declines in the abundance of some species, although observations are site- or habitat-specific and generally in upland areas. Climate change may also have significant indirect effects: phenological events are happening earlier for several species groups (Parmesan, 2007). Such asynchrony could alter interactions between plants, herbivores, predators and pollinators (Bartomeus et al., 2013)

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and may lead, for example, to segregation between plants and pollinators, and between food plants and phytophagous species (Willmer, 2012).

5. This proposal sets out a conservation strategy for terrestrial invertebrates. It

covers four of the five strategic goals included in the Aichi Targets and the European Union's Biodiversity Strategy: 1. Address the causes of biodiversity loss; 2. Reduce the direct pressure on biodiversity and promote sustainable use; 3. Safeguard ecosystems, species and genetic diversity; and 4. Participatory planning, capacity building (by targeting biodiversity values, functioning, status and trends). This strategy also complements other initiatives such as SNH's Species Decision Tool, the Pollinator Strategy for Scotland, and the Climate Change Strategy (Climate change and nature in Scotland 2012). Moreover, it underpins the protection established by law, e.g., Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora, the Wildlife and Countryside Act 1981, Conservation Regulations 1994 and The Nature Conservation (Scotland) Act 2004.

Approach

6. A UK list of priority species for conservation was developed under the UK Biodiversity Action Plan (UK BAP) in 1994, which was revised and updated by JNCC and Defra (UK Post-2010 Biodiversity Framework) on behalf of all four UK governments (the Four Countries' Biodiversity Group). The UK list of priority species served as the basis for the current statutory framework for biodiversity conservation in Scotland, the Scottish Biodiversity List. From this list, the terrestrial invertebrates with greatest need of conservation action were identified according to following criteria:

Threat. This criterion is centred on IUCN's (2012) categories Vulnerable, Endangered and Critically Endangered, and on the older British Red Data Book's (RDB) categories Endangered (RDB1), Vulnerable (RDB2) and Rare (RDB3). The IUCN criteria for threat focus on perceived danger of extinction. However, due to the scarcity of data for the overwhelmingly majority of invertebrates, most of the relatively few IUCN assessments of threat are limited to information on geographic range (Cardoso et al., 2011). The RDB categories are also based on geographic distribution, namely area of occupancy (number of 10-km squares), without taking into account trends for increase or decline. This focus on a single variable, i.e., distribution, to assess threat is not too problematic because range is broadly correlated with population size for many plant and animal groups (Lawton, 1993; Brown, 1995; He & Gaston, 2000).

Endemism. Endemic species are confined to a certain region or have a relatively limited distribution, therefore they are highly adapted to their home range. Since endemic species are restricted to particular areas, they are intrinsically susceptible to extinction because any environmental disturbance could decrease their numbers to dangerous levels or wipe them out entirely. Endemic species are often considered indicators or surrogates of biodiversity and the focus for the conservation. Endemism, combined with rarity in its different forms (Rabinowitz et al., 1986), are the factors that confer the greatest risk of extinction (Myers et al., 2000; Gaston, 2003).

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Endemic species are of high priority because Scotland has the sole responsibility for their protection: this is an international duty of care, because if endemic species become extinct in Scotland, the world's biodiversity becomes poorer.

Relevance. Size and importance of Scottish populations within GB.

Knowledge. Realistic conservation measures are only possible when there is sufficient information about the species' biology, ecology, and management requirements.

7. Based on the above conditions, species were classified according to the following hierarchical categories of priority:

1. Endemic species (in Scotland or GB) known or believed to be under threat or vulnerable.

2. Species with a significant proportion of their GB population in Scotland (near endemics) that are known or believed to be threatened or vulnerable, and for which management measures or risk factors are known.

3. Species known or believed to be threatened or vulnerable and for which management measures or risk factors are known. In most cases we have reasonably understanding of species' biology, ecology, distribution, and conservation history.

4. Species of conservation concern but whose occurrence in Scotland is doubtful; species of conservation concern for which there is insufficient information, i.e., monitoring and research are the only realistic options available; species that are intrinsically vulnerable but do not require immediate action.

Output

8. This screening identified 179 species of priority levels 1 to 4. These are mostly endemics, species under threat or vulnerable, species with significant populations in Scotland, and species for which management measures are available.

Proposed actions

9. Actions aimed at species on restricted sites. A few priority species have well-defined and relatively restricted distributions, which range from a single site to a few locations within the same geographical area. These species are intrinsically at risk of local extinctions because they are particularly vulnerable to stochastic factors such as fire, floods, severe weather, etc. For these cases, conservation practices can be detailed and tailored. There are ongoing measures for some of these species, but their safeguard requires long-time commitments.

10. Actions aimed at habitats. For the majority of terrestrial invertebrates, broad habitat management practices are the most pragmatic conservation options available because the species are widely distributed, or our understanding of their ecological requirements is limited. Moreover, it is reasonable to assume that populations are secure as long as their habitats are in a 'steady state' (at least

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within a reasonable period of time; all habitats eventually evolve - as for example in response to climate change). Therefore habitat management and assessment may turn out to be the best options. Habitat quality may also be used as a proxy to conservation status of species and assemblages in cases of logistical constraints, e.g., insufficient resources, or unavailability of entomological expertise.

11. Climate change actions. Changes in phenology have proven to be some of the most conspicuous reactions by wildlife in response to recent climatic warming (Walther, 2010), although almost nothing is known about long-term population-level effects of population shifts and phenology. However, our understanding of the processes involved is poor and therefore the magnitude of climate-induced effects cannot currently be predicted. The best course of action is to monitor the priority species more likely to be susceptible, and increase our knowledge about their biology and ecology. Actions for species likely to respond to climate change address three of the eight adaptation principles in SNH' Corporate Plan Climate change and nature in Scotland: reduce pressures on habitats and species, improve habitat management, and consider translocation of species.

12. Survey. Invertebrates are intrinsically scarce and difficult to find, therefore records are often limited, outdated or questionable; we may be uncertain about the distribution of some priority species or even whether they are extant. In these instances, surveys are the most appropriate actions. Other species are potentially vulnerable but not believed to be currently under threat, therefore no immediate measures are required. For these species, monitoring programmes to confirm their distribution or assess population sizes should suffice.

13. Research. The greatest obstacle to insect conservation is the scarcity of basic information about species biology and ecology (Fry & Lonsdale, 1991; Bossart & Carlton, 2002). This lack of information is critical: 'for many invertebrates, knowledge is insufficient to formulate any realistic conservation plan extending beyond bland generalities without insights from a strong research component' (New, 2011). We need to support and encourage efforts to close the gaps in our understanding of basic aspects of invertebrate conservation such as taxonomy, biology and ecology, and boost the public profile of invertebrates.

The draft Strategy

14. Founded on these principles, Annex 1 sets out a first draft conservation strategy for terrestrial invertebrates in Scotland. The level of ambition and proposed actions are provisional subject to wider consultation with specialists, key bodies and the Scottish Government.

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ANNEX 1. Draft SNH Conservation Strategy for Terrestrial Invertebrates. Introduction Invertebrates dominate virtually every ecosystem in the world regarding species richness, biomass and ecological services. They represent about 80% of Earth's species, while arthropods (invertebrates with an exoskeleton, that is, insects, spiders, millipedes, centipedes and crustaceans) are responsible for approximately 82% of all animal diversity. Over a million species of terrestrial invertebrates have been described, making up 96% of known terrestrial species. Their diversity has been estimated to lie between 3 million and as many as 80 million species (Hammond, 1992; Hawksworth & Kalin-Arroyo, 1995; Mora et al., 2011).

World Conservation Monitoring Centre

Invertebrates are the basis of most food chains, and are vital links as herbivores, predators, parasites or decomposers. Invertebrates play essential roles in the functioning of ecosystems such as organic decomposition and nutrient cycling, pollination, pest control, and seed dispersal (Daily et al., 1997). They provide the basis to many processes which humans depend on. For example, dung beetles are very effective at decomposing waste from wildlife and livestock. This helps to enhance forage palatability, recycle nitrogen into the system, and reduce incidence of pests. These ecosystem services are estimated to be worth billions of pounds to

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the global economy each year (Losey & Vaughan, 2006; Collen et al., 2012). Invertebrates are also the soil's ecosystem engineers, enhancing microbial activity, accelerating decomposition and mediating transport processes. As most, if not all, terrestrial organisms depend directly or indirectly on biological processes in the soil, soil invertebrates are keystone organisms, underpinning life on Earth: without them the world’s ecosystems could collapse (Wilson, 1987; Stork & Eggleton, 1992). Scotland is the home of at least 24,000 invertebrate species (more than 12 times the number of all UK bird, mammal and vascular plant species combined). Many of those species, particularly in montane, upland and boreal habitats, have become rare or extinct elsewhere in the UK or Europe (Ravenscroft, 1995; Rotheray & MacGowan, 1996; Macadam & Rotheray, 2009). Main threats to Scottish invertebrates Habitat loss and fragmentation, land conversion, agricultural intensification, landscape homogenisation, urbanization, pesticides and pollution have been identified as the main threats to invertebrate species in Scotland and elsewhere (Vitousek et al., 1997; Macadam & Rotheray, 2009; Aspinall et al., 2011). Recently, climate change has been recognised as one of the main long-term threats to biodiversity. There is limited evidence that climate changes are causing declines in the abundance of some species, although observations are site- or habitat-specific and generally in upland areas. Climate change may also have significant indirect effects: phenological events are happening earlier for several species groups (Parmesan, 2007). Such asynchrony could alter interactions between plants, herbivores, predators and pollinators (Bartomeus et al., 2013) and may lead, for example, to segregation between plants and pollinators, and between food plants and phytophagous species (Willmer, 2012). Purpose This document is the first draft of the SNH conservation strategy for Scotland’s terrestrial invertebrates, set in the context of our current understanding of the importance of the invertebrate assemblages and threats to these. Policy context The strategic context for this is the Scottish Biodiversity Strategy, which is outlined in two main documents:

Scotland's Biodiversity: It's in Your Hands, published by the Scottish Government in 2004.

The 2020 Challenge for Scotland's Biodiversity (2013). Scotland's Biodiversity - A Route Map to 2020 (2015) sets out the projects required to meet the 2020 Challenge, with reference to on-going work on invertebrate conservation ('Priority Project 9 - Conservation of priority species). The 2020 Challenge is Scotland’s response to the Aichi Targets set by the United Nations Convention on Biological Diversity and the European Union's Biodiversity Strategy for 2020.

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This draft invertebrate strategy focuses on species of conservation concern for which viable, relevant and evidence-based measures are available. The Route Map to 2020 has emphasised the conservation of priority species as one of the main objectives of the Scotland’s Biodiversity Strategy: Priority Project 9: conservation of priority species. Aim: deliver focused action for priority species in Scotland. The Route Map also highlights the need to publish and implement conservation and management priorities for species in the Scottish Biodiversity List, which forms the basis of this document. Four of the five strategic goals included in the Aichi Targets and the EU Biodiversity Strategy are covered here: 1. Address the causes of biodiversity loss; 2. Reduce the direct pressure on biodiversity and promote sustainable use; 3. Safeguard ecosystems, species and genetic diversity; 4. Participatory planning, capacity building (by targeting biodiversity values, functioning, status and trends). This strategy also complements other initiatives such as SNH's Species Decision Tool, the Pollinator Strategy for Scotland, and the Climate Change Strategy (Climate change and nature in Scotland 2016). Moreover, it underpins the protection established by law, e.g., Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora, the Wildlife and Countryside Act 1981, Conservation Regulations 1994 and The Nature Conservation (Scotland) Act 2004. Ambition By 2023, we aim for the following: 1. Declines in rare and threatened species has been halted or reversed, so that species are removed from the priority list. 2. Measures for the conservation of all priority species and their habitats have been adopted. 3. A better understanding of priority species distribution and ecology. 4. The most important invertebrate habitats are protected, managed or restored so that their biodiversity and ecological functions are maintained or improved. 5. All of our statutory protected areas with invertebrate features should be moving towards favourable condition. 6. The importance and benefits of invertebrates will be better recognised by the Scottish public. 7. More people will be involved in monitoring and recording Scottish invertebrates. 8. Statutory agencies, non-governmental organisations (NGOs), communities and individuals across Scotland are brought together to create an impetus for invertebrate conservation. 9. Invertebrates are taken into account in government policies, valued by our staff, and land managers. Approach A UK list of priority species for conservation was developed under the UK Biodiversity Action Plan (UK BAP) in 1994, which was revised and updated by JNCC and Defra (UK Post-2010 Biodiversity Framework) on behalf of all four UK

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governments (the Four Countries' Biodiversity Group). The UK list of priority species served as the basis for the current statutory framework for biodiversity conservation in Scotland, the Scottish Biodiversity List. Species from this list with greater need of conservation action in Scotland were identified according to following criteria:

Threat. This criterion is centred on IUCN's (2012) categories Vulnerable, Endangered and Critically Endangered, and on the older British Red Data Book's (RDB) categories Endangered (RDB1), Vulnerable (RDB2) and Rare (RDB3) (Shirt, 1987; Bratton, 1991). The IUCN criteria for threat focus on perceived danger of extinction, which is assessed by population trends, population size and structure, geographic range, and quantitative analyses such as population viability. However, due to the scarcity of data for the overwhelmingly majority of invertebrates, most of the relatively few IUCN assessments of threat are limited to information on geographic range (Cardoso et al., 2011a). The RDB categories are also based on geographic distribution, namely area of occupancy (number of 10-km squares), without taking into account trends for increase or decline. This focus on a single variable, i.e., distribution, to assess threat is not too problematic because range is broadly correlated with population size for many plant and animal groups (Lawton, 1993; Brown, 1995; He & Gaston, 2000).

Endemism. Endemic species are confined to a certain region or have a relatively limited distribution, therefore they are highly adapted to their home range. Since endemic species are restricted to particular areas, they are intrinsically susceptible to extinction because any environmental disturbance could decrease their numbers to dangerous levels or wipe them out entirely. Endemic species are often considered indicators or surrogates of biodiversity and the focus for the conservation. Endemism, combined with rarity in its different forms (Rabinowitz, 1981; Rabinowitz et al., 1986), are the factors that confer the greatest risk of extinction (Myers et al., 2000; Gaston, 1994; 2003). Endemic species are of high priority because Scotland has the sole responsibility for their protection: this is an international duty of care, because if endemic species become extinct in Scotland, the world's biodiversity becomes poorer.

Relevance. Size and importance of Scottish populations within GB.

Knowledge. Realistic conservation measures are only possible when there is sufficient information about the species' biology, ecology, and management requirements.

Based on the above conditions, species were classified according to the following hierarchical categories of priority:

1. Endemic species (in Scotland or GB) known or believed to be under threat or vulnerable.

2. Species with a significant proportion of their GB population in Scotland (near

endemics) that are known or believed to be threatened or vulnerable, and for which management measures or risk factors are known.

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3. Species known or believed to be threatened or vulnerable and for which

management measures or risk factors are known. In most cases we have reasonably understanding of species' biology, ecology, distribution, and conservation history.

4. Species of conservation concern but whose occurrence in Scotland is

doubtful; species of conservation concern for which there is insufficient information, i.e., monitoring and research are the only realistic options available; species that are intrinsically vulnerable but do not require immediate action.

The spreadsheet Species of conservation concern in Scotland lists 179 terrestrial invertebrate species identified as of priority levels 1 to 4, and includes summaries of these species' ecology, distribution, threats and required conservation measures. These are mostly endemics, species under threat or vulnerable, species with significant populations in Scotland, and species for which management measures are available. One of the caveats of selecting priorities is that 'any and every list of invertebrate species of conservation concern, however these are selected or given priority, will be both too long for all the species to be dealt with individually and too short to be ecologically or taxonomically even reasonably representative of those needing that attention' (New, 2009). Nonetheless, this initiative can be seen as an initial step, to be fine-tuned and improved with time. The list itself is dynamic: species will be added or removed as their conservation status change which will be assessed annually. It is important to emphasise that most of the species listed can be viewed as 'umbrella species', that is, species targeted for conservation practices that indirectly benefit other species and the wider habitat (Groom et al., 2006). They are also 'flagship species' sensu Heywood (1995): charismatic species that serve as symbols and rallying points to stimulate conservation awareness and engagement. Conservation actions 1. Actions aimed at species on restricted sites A few priority species have well-defined and relatively restricted distributions, which range for a single site to a few locations within the same geographical area. These species are intrinsically at risk of local extinctions because they are particularly vulnerable to stochastic factors such as fire, floods, severe weather, etc. For these cases, conservation practices can be detailed and tailored. There are ongoing measures for some of these species, but their safeguard requires long-time commitments.

Species Priority GB distribution

Botanophila fonsecai - Fonseca's seed fly

1 The whole world distribution consists of a single site in Scotland - a 8.1 km of shore at Dornoch sands, Sutherland.

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Zygaena loti scotica - Slender scotch burnet

1 Five populations on the islands of Mull and Ulva in western Scotland. Most populations are within SSSI or National Trust for Scotland land.

Zygaena viciae argyllensis - New Forest burnet

1 One site in western Scotland: Ardnamurchan Coast.

Chrysolina latecincta (= Chrysomela latecincta)

2 Keen of Hamar NNR (Orkney) cliff-tops and Eastern England. Possibly under-recorded because it is nocturnal.

Cryptocephalus decemmaculatus - Ten-spotted pot beetle

2 Wybunbury Moss (Cheshire) and Camghouran (Perthshire) NN595563, where the species was rediscovered in 2017.

Cryptocephalus sexpunctatus - Six-spotted pot beetle

2 Stockbridge Down (Hants) and Kirkconnell Flow, where the species was rediscovered in 2017.

Megalomus hirtus - Bordered brown lacewing

2 A single site: Arthur’s Seat, Edinburgh.

Hammerschmidtia ferruginea - Aspen hoverfly

2 All eight populations in Scotland, mainly at Strathspey, also Nairn and Sutherland.

Blera fallax - Pine hoverfly

2 All populations confined to eight sites in a Strathspey area between Aviemore and Grantown.

Stratiomys chamaeleon 3 Several localities in England, one in the Highlands: Braelangwell Wood SSSI.

2. Actions aimed at habitats For the majority of terrestrial invertebrates, broad habitat management practices are the most pragmatic conservation options available because the species are widely distributed, or our understanding of their ecological requirements is limited. Moreover, it is reasonable to assume that populations are secure as long as their habitats are in a 'steady state' (at least within a reasonable period of time; all habitats eventually evolve - as for example in response to climate change). Therefore habitat management and assessment may turn out to be the best options. Habitat quality may also be used as a proxy to conservation status of species and assemblages in cases of logistical constraints, e.g., insufficient resources, or unavailability of entomological expertise. 2.1. Woodland There are 21 woodland species identified as priorities 1 to 3, and most of them are dependent on dead or decaying wood or fungal bodies (saproxylic components). In fact, there are around 1700 species of saproxylic insects in Britain, of which about 40% are RDB species or Nationally Scarce; 28 of these species occur in Scotland (Alexander, 2005). This fauna's main requirements are (Kirby, 1992; Bremer & Farley, 2010; Bellamy & Charman, 2012):

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Woodland adequate physical structure. The best invertebrate habitats comprise plants of a wide range of age and height to maximise the diversity of niches and microhabitats. Gradual transitions at woodland edges and ride margins are also desirable. Wood should be left to decay naturally where it fells (naturally or by cutting), including if it is partly submerged in water.

Non-forestry components. Veteran trees, under-storey trees, climbers (e.g., ivy, honeysuckle) and shrubs such as hazel, hawthorn and brambles enhance biodiversity and provide food and shelter for many invertebrates. Some of these plants (e.g., hawthorn and blackthorn) are sources of pollen for bees, butterflies and flies.

Clearings. Open areas resulting from fires and tree falls are important woodland features because they provide areas for feeding, sunning and breeding for the saproxylic fauna and for bees, butterflies and hoverflies as well. Rides, tracks and way-leaves with sunny, flower-rich margins can function as clearings if they are wide enough and properly maintained.

2.2. Upland and moorland Most of the 10 priority species in upland and moorland (considered here as part of a broad habitat that includes heathland) depend on one or a few plants for larval food or as pollen and nectar sources. The following aspects are particularly important for the priority species and their habitats:

Structural diversity, comprising exposed ground and vegetation mosaics such as a heathland-grassland combination. These mosaics are preferably maintained by heather-cutting and grazing, although burning may be the only management option for some sites. In this case, only small patches of heather should be burnt at a time to allow invertebrates to re-colonize from neighbouring vegetation.

Maintenance of the hydrological conditions of streams, seepages, flushes, boggy pools, Sphagnum lawns and wet peat. Retaining the alkaline condition of the waters is the most important conservation measure for whorl snails (Vertigo spp.).

Light cattle grazing. Moderate levels of grazing maintain a grassland-heather mosaic and prevent scrub encroachment and birch regeneration. Cattle is preferable to sheep as their grazing produce a more diverse vegetation structure with varying sward heights and tussocks that provide shelter and overwintering sites.

2.3. Aquatic habitats Rivers, streams, ditches, springs, seepages, ponds or lakes are habitats for 10 priority aquatic or semiaquatic species. These habitats have been threatened by agriculture, housing developments and industry. Invertebrates need to be considered in maintenance and engineering work to minimise changes to river morphology,

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habitat loss and excessive river-bed disturbance. Because of their small scale, springs and flushes are particularly vulnerable to land use changes and disturbance by machinery and by pond creation schemes. Fast-flowing streams with natural riffles, pool systems and a gravel substrate have rich, specialised invertebrate communities of mayflies, stoneflies, caddisflies, beetles and flies. In agricultural and built-up areas, streams have been straightened or modified to the detriment of their fauna. Field ponds, woodland ponds and sphagnum pools provide distinctive invertebrate habitat, especially for dragonflies, beetles, caddisflies, water bugs, flies, spiders and snails. Even seasonal pools can be valuable for invertebrates; indeed, in some situations they harbour species not found in more permanent water bodies, probably because predators are scarce. Bogs: Invertebrate species richness is relatively low in these habitats, but bogs are important for some specialised species such as the large heath, azure hawker (Aeshna caerulea) and the northern emerald dragonfly (Somatochlora arctica). Also, bogs' invertebrate biomass is of major importance for other conservation priorities such as breeding waders. River sand and shingle, collectively known as Exposed Riverine Sediments (ERS): River banks of shingle, sand and silt that are submerged over the winter and exposed in the spring and summer are breeding grounds for a large number of specialized invertebrate species, mainly beetles, flies and spiders, of which 11 are RDB species in Scotland. 2.4. Grassland and coastal areas Species-rich, flower-rich, structurally diverse habitats are particularly important for most of the 12 grassland and coastal priority invertebrates. Management should aim to establish a good mosaic of habitats, including bare ground, short turf, long grass and some scrub (Dennis et al., 2008). These mosaics are best maintained by appropriate levels of grazing. High livestock density and high cutting frequency are detrimental because they will create uniform expanses of short turf that support few species. On the other hand insufficient grazing or cutting result in rank swards and bracken invasion. Fertilisation is also an important factor: high nutrient levels in the soil encourage dominance by a few competitive grasses at the expense of a greater variety of slower-growing species. 3. Climate change actions According to current global warming models, Scotland will become warmer, wetter and more prone to extreme weather events (Morecroft & Speakman, 2015). These changes can be beneficial to invertebrates in the short-term: if winters are warmer, spring comes sooner and summer lasts longer, thus invertebrates will have higher reproductive rates (Bale et al., 2002). In fact, it is expected that numbers of most UK butterfly species will increase or, in a few cases, remain stable, whereas the only species for which a substantial decline is predicted under climate warming is the large white (Pieris brassicae), a main agricultural pest (Roy et al., 2008). On the

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other hand, models based on paleoecological records predict that species in temperate regions will respond to global warming by migrating northwards at a regional level and upwards at a local level to keep up within their temperature tolerance ranges (Rooney et al., 1996). In fact, some invertebrate species have recently colonised England from continental Europe and are expanding northwards (Mossman et al., 2013). Populations can respond to a changing environment by dispersal, following optimal conditions through space, or adapting to the new conditions (Roy et al., 2015). However, species without dispersal capacity or sufficient phenotypic plasticity to adapt could disappear. In Britain, some cool-adapted butterflies with narrow temperature tolerances are experiencing extinctions at their low latitude or elevation margins (Franco et al., 2006; Thomas et al., 2006). Changes in phenology have proven to be some of the most conspicuous reactions by wildlife in response to recent climatic warming (Walther et al., 2002; Walther, 2010), although almost nothing is known about long-term population-level effects of population shifts and phenology. Arctic or alpine species for example may become isolated and eventually vanish from current pockets of habitats. However, our understanding of the processes involved is poor and therefore the magnitude of climate-induced effects cannot currently be predicted. Corridors have been proposed as mitigation measures to help species migrate. However, the efficacy of corridors links for most species is unknown (Haslett & Traugott, 2000). The best course of action is to monitor the priority species more likely to be susceptible, and increase our knowledge about their biology and ecology:

Species Priority

Main requirements

Ameletus inopinatus - Upland summer mayfly

4 The only arctic-alpine Ephemeroptera recorded from the British Isles. Larvae are found in upland streams and lochs.

Bombus monticola - Bilberry bumble bee

3 Strongly associated with upland heathland and moorland at up to 1,000 m.

Erebia epiphron - Mountain ringlet

3 Mountain grassland characterised by bilberry and wavy hair-grass at altitudes of 350-900 m.

Okeniella caudata 4 This fly, previously associated with the high arctic and Scandinavian tundra, was discovered in Scotland in 2015.

Rhamphomyia hirtula - Mountain dance-fly

4 Only found on the highest mountains, between 800 and 1100 m.

Vertigo modesta - Arctic whorl snail

4 Only known from two high-altitude small areas of calcareous arctic-alpine habitats in the Highlands.

Xestia alpicola - Northern dart 3 Restricted to upland and montane areas, generally above 450 m.

Some initiatives, in the form of citizen science projects, could include non-priority

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species that have experienced substantial shifts in their distribution possibly as a result of climate change, such as the orange-tip (Anthocharis cardamines) and ringlet (Aphantopus hyperantus) butterflies, as well as montane or cool-adapted species such as Scotch argus (Erebia aethiops), Large heath (Coenonympha tullia) and northern dart (Xestia alpicola). Or the upland summer mayfly (Ameletus inopinatus), which is expected to be increasingly confined to the higher altitude rivers in Scotland (Taubmann et al., 2010). Actions for species likely to respond to climate change address three of the eight adaptation principles in SNH' Corporate Plan Climate change and nature in Scotland: reduce pressures on habitats and species, improve habitat management, and consider translocation of species. They also identify indicators that can be used to assess climate change impact by surveillance and monitoring. 4. Survey Invertebrates are intrinsically scarce and difficult to find, therefore records are often limited, outdated or questionable; we may be uncertain about the distribution of some priority species or even whether they are extant. In these instances, surveys are the most appropriate actions. Other species are potentially vulnerable but not believed to be currently under threat, therefore no immediate measures are required. For these species, monitoring programmes to confirm their distribution or assess population sizes should suffice. For six of the selected priority species, monitoring or survey are the only actions proposed: Peus's long-back spider (Mecopisthes peusi), western mason bee (Osmia parietina), the spider the northern dart (Xestia alpicola), sword grass (Xylena exsoleta), mountain ringlet (Erebia epiphron) and the braconid wasp Earinus transversus. 5. Research The greatest obstacle to insect conservation is the scarcity of basic information about species biology and ecology (Fry & Lonsdale, 1991; Bossart & Carlton, 2002). This lack of information is critical: 'for many invertebrates, knowledge is insufficient to formulate any realistic conservation plan extending beyond bland generalities without insights from a strong research component' (New, 2011). Cardoso et al. (2011b) identified the main scientific gaps for the development of conservation plans for invertebrates:

Most species are undescribed.

The distributions of identified species are mostly unknown.

The abundance of species and their changes in space and time are unknown.

Species’ ecology and sensitivity to habitat changes are largely unknown. We need to support and encourage efforts to close the gaps in our understanding of basic aspects of invertebrate conservation such as taxonomy, biology and ecology, and boost the public profile of invertebrates. Making it happen The table below is a summary of the work necessary to address the conservation

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requirements of priority species.

Target Expected outcomes

Sites

Dornoch sands (B. fonsecai)

The site is targeted for mitigation measures to protect the species from consequences of the proposed development.

Mull and Ulva (Z. loti)

All extant sites are regularly monitored and managed, mostly by grazing levels and cotoneaster clearance (at Kilninian). Pheromone lures developed to assist survey and monitoring.

Ardnamurchan Coast (Z. viciae)

The site's perimeter fence is maintained to prevent sheep from invading the site. Sympathetic grazing in place, which is determined by monitoring of adults (annually) and vegetation (as required). Pheromone lures have been successfully developed to assist survey and monitoring. Additional exclosures have been created to expand suitable habitat.

Keen of Hamar NNR (C. latecincta)

Survey carried at the known site. Work with management to maintain conditions at the site.

Camghouran (C. decemmaculatus)

Work carried with landowner/manager to improve conditions at the site.

Kirkconnell Flow (C. sexpunctatus)

Work carried with landowner/manager to improve conditions at the site.

Arthur’s Seat (M. hirtus) Further surveys carried. An implementation and management plan prepared with landowner/ manager.

Strathspey (H. ferruginea)

Aspen management is included in FCS plans for Inverfarigaig and Achany: at least 3 years worth of suitable deadwood retained at any time, and all dead wood locations maintained at a suitable dispersal distance from one another (< 5 km). Management / monitoring regime created for Findhorn. Volunteer monitoring maintained at key sites in Strathspey. Aspen deadwood register maintained.

Strathspey (B. fallax)

Continuation of the annual stump-cutting programme at the sites to increase habitat availability and fresh stump material. Creation and maintenance of a register of "breeding stumps" at all native and translocated sites. Annual monitoring carried by volunteers. Maintain the captive population programme at the Edinburgh Zoo.

Braelangwell Wood SSSI (S. chamaeleon)

Vegetation kept open and relatively short at seepages and pools by light grazing. Dig pools to provide open habitat if existing ones become overgrown, though an emphasis must be on preserving older seepages and fens and their subtle hydrology/water chemistry.

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Habitats

Woodland

Policies and guidance to protect and enhance saproxylic habitats and their invertebrate species are updated if necessary and made widely available.

Upland and moorland

Update guidance that addresses the requirement of invertebrate species, particularly in relation to overgrazing, conversion to grassland and afforestation.

Aquatic

Develop guidance that addresses specific requirements for priority species, such as water quality, abstraction, damage to watercourses, disturbances to riparian vegetation, drainage and infilling of shallow ponds, loss of oxbow systems. For the freshwater pearl mussel: target key river catchments for management and habitat improvement; carry out translocations; continue campaigns against illegal fishing and trade.

Grassland and coastal

Update guidance that addresses the requirement of priority species, particularly in relation to agricultural intensification, over-grazing, development, afforestation and invasion by non-native plants. Promote creation of demonstration sites for good habitat management.

Climate change actions

Continued support a NERC iCASE PhD studentship project to assess the climatic effects on three Scottish moths: mountain ringlet, Scotch argus and the large heath. Encourage similar initiatives from partners.

Survey & Monitoring

Encourage public engagement in recording and monitoring. Development and improvement of standardised monitoring schemes for species and species groups.

Research

Promote the development of standardized protocols for inventorying and monitoring for species and species groups.

Support contributions to taxonomic information, especially identification skills and rapid assessment DNA techniques (e.g., barcoding).

Make greater use public engagement in recording, monitoring and cataloguing species

Promote the collation of ecological, behavioural and biological information.

Promote the transfer of information and records between amateur, professional and academic organizations, and policy makers.

Ensure that invertebrates are addressed in environmental impact studies.

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