Mark S. Parsons

Long-term changes to the frequency of occurrence of British moths are consistent with opposing and synergistic effects of climate and land-use changes

Summary Species’ distributions are likely to be affected by a combination of environmental drivers. We used a data set of 11 million species occurrence records over the period 1970–2010 to assess changes in the frequency of occurrence of 673 macro‐moth species in Great Britain. Groups of species with different predicted sensitivities showed divergent trends, which we interpret in the context of land‐use and climatic changes. A diversity of responses was revealed: 260 moth species declined significantly, whereas 160 increased significantly. Overall, frequencies of occurrence declined, mirroring trends in less species‐rich, yet more intensively studied taxa. Geographically widespread species, which were predicted to be more sensitive to land use than to climate change, declined significantly in southern Britain, where the cover of urban and arable land has increased. Moths associated with low nitrogen and open environments (based on their larval host plant characteristics) declined most strongly, which is also consistent with a land‐use change explanation. Some moths that reach their northern (leading edge) range limit in southern Britain increased, whereas species restricted to northern Britain (trailing edge) declined significantly, consistent with a climate change explanation. Not all species of a given type behaved similarly, suggesting that complex interactions between species’ attributes and different combinations of environmental drivers determine frequency of occurrence changes. Synthesis and applications. Our findings are consistent with large‐scale responses to climatic and land‐use changes, with some species increasing and others decreasing. We suggest that land‐use change (e.g. habitat loss, nitrogen deposition) and climate change are both major drivers of moth biodiversity change, acting independently and in combination. Importantly, the diverse responses revealed in this species‐rich taxon show that multifaceted conservation strategies are needed to minimize negative biodiversity impacts of multiple environmental changes. We suggest that habitat protection, management and ecological restoration can mitigate combined impacts of land‐use change and climate change by providing environments that are suitable for existing populations and also enable species to shift their ranges.

Habitat preference and mobility of Polia bombycina: are non-tailored agri-environment schemes any good for a rare and localised species?

General agri-environment schemes (AES) have been shown to benefit widespread species, but there is little information on the extent to which rare, more localised, species may also benefit. We tested whether AES options aimed at increasing general biodiversity also benefit a highly endangered moth, Poliabombycina, without species-specific tailoring. We assessed effects on its abundance of two AES options, wide field margins and hedgerow trees, using light traps at the landscape-scale and for mark-release-recapture at the farm-scale. We hypothesized that abundance would be highest at wide field margins and at hedgerow trees, and that if hedgerow trees conferred a positive effect, individuals would be more likely to follow hedgerows than crossing exposed fields while on the move. The results showed that significantly more individuals were captured at sites with a hedgerow tree. Numbers were also higher at wide margins, but this was not statistically significant, and no individuals were caught at field centres. Our study suggests that general options within appropriately designed and implemented AES aimed at increasing overall biodiversity in intensive agricultural landscapes have the potential to not only benefit common, widespread habitat generalists, but some rare and more endangered species as well. P. bombycina serves as an example of how general AES options, existing and novel ones alike, might cater for the needs of rare and localised species. As the precise ecological requirements of most invertebrate species remain unknown, we urge scientists and governments to address the challenge to research and design truly general AES, which options should be able to deliver not only for widespread species but also for the less-widespread counterpart of farmland biodiversity.

Agricultural Management and Climatic Change Are the Major Drivers of Biodiversity Change in the UK.

Action to reduce anthropogenic impact on the environment and species within it will be most effective when targeted towards activities that have the greatest impact on biodiversity. To do this effectively we need to better understand the relative importance of different activities and how they drive changes in species’ populations. Here, we present a novel, flexible framework that reviews evidence for the relative importance of these drivers of change and uses it to explain recent alterations in species’ populations. We review drivers of change across four hundred species sampled from a broad range of taxonomic groups in the UK. We found that species’ population change (~1970–2012) has been most strongly impacted by intensive management of agricultural land and by climatic change. The impact of the former was primarily deleterious, whereas the impact of climatic change to date has been more mixed. Findings were similar across the three major taxonomic groups assessed (insects, vascular plants and vertebrates). In general, the way a habitat was managed had a greater impact than changes in its extent, which accords with the relatively small changes in the areas occupied by different habitats during our study period, compared to substantial changes in habitat management. Of the drivers classified as conservation measures, low-intensity management of agricultural land and habitat creation had the greatest impact. Our framework could be used to assess the relative importance of drivers at a range of scales to better inform our policy and management decisions. Furthermore, by scoring the quality of evidence, this framework helps us identify research gaps and needs.

Light trap transects – a field method for ascertaining the habitat preferences of night-flying Lepidoptera, using Mythimna turca (Linnaeus 1761) (Lepidoptera: Noctuidae) as an example

The habitat associations of the noctuid moth Double Line Mythimna turca (Linnaeus 1761) were studied in three areas in Britain by setting up light traps equidistant alon0g transects which passed through different habitat types. Counts were made of M. turca at each trap station and the results compared with the habitat present in the vicinity of each trap. The results using chi-square analysis indicate that the preferred habitats for M. turca are woodland and Pteridium aquilinum scrub, especially where the grasses Agrostis capillaris and Holcus mollis occur. The environmental factors affecting moth catches are discussed and chi-squared expectations are adjusted to take account of the different efficiency of light traps in open grassland and woodland situations. The light trap transect method is shown to be useful for moth species where little is known of their ecology and can be used to provide a straightforward insight informing additional targeted autecological studies. The methodology may be less suited to those species which occur at low density, are poorly attracted to light or are known to migrate.

The United Kingdom Biodiversity Action Plan moths – selection, status and progress on conservation

As a result of the Earth Summit in 1992, 53 species of moth are covered by the UK Governments Biodiversity Action Plan. The background to the UK Biodiversity Action Plan and the selection of species is discussed. Butterfly Conservations Action for Threatened Moths Project is covered along with its role and approach in overseeing the implementation of the moth Action Plans. A case study on the Straw Belle Aspitates gilvaria (Denis and Schiffermüller) is presented as an example of how an individual Action Plan is being implemented. A subjective consideration of the biological progress with the moth Action Plans is given along with a brief discussion of possible future developments for the UK BAP approach for moths.

Decline of a Rare Moth at Its Last Known English Site: Causes and Lessons for Conservation

The conditions required by rare species are often only approximately known. Monitoring such species over time can help refine management of their protected areas. We report population trends of a rare moth, the Dark Bordered Beauty Epione vespertaria (Linnaeus, 1767) (Lepidoptera: Geometridae) at its last known English site on a protected lowland heath, and those of its host-plant, Salix repens (L.) (Malpighiales: Salicaceae). Between 2007 and 2014, adult moth density reduced by an average of 30–35% annually over the monitored area, and its range over the monitored area contracted in concert. By comparing data from before this decline (2005) with data taken in 2013, we show that the density of host-plants over the monitored area reduced three-fold overall, and ten-fold in the areas of highest host-plant density. In addition, plants were significantly smaller in 2013. In 2005, moth larvae tended to be found on plants that were significantly larger than average at the time. By 2013, far fewer plants were of an equivalent size. This suggests that the rapid decline of the moth population coincides with, and is likely driven by, changes in the host-plant population. Why the host-plant population has changed remains less certain, but fire, frost damage and grazing damage have probably contributed. It is likely that a reduction in grazing pressure in parts of the site would aid host-plant recovery, although grazing remains an important site management activity. Our work confirms the value of constant monitoring of rare or priority insect species, of the risks posed to species with few populations even when their populations are large, of the potential conflict between bespoke management for species and generic management of habitats, and hence the value of refining our knowledge of rare species’ requirements so that their needs can be incorporated into the management of protected areas.

Host-plant patch qualities and presence of a likely competitor species affect the distribution and abundance of a rare British moth, Cucullia lychnitis

Understanding the environmental factors that affect the distribution and abundance of rare and threatened species can help identify priority sites for conservation action such as habitat management. The moth Cucullia lychnitis is identified in UK legislation as a priority species for conservation. Its conspicuous larvae feed on a patchily distributed host plant Verbascum nigrum, but are entirely absent from some host plant patches within the species’ range. Environmental variability among patches was investigated to understand factors affecting (i) patch occupancy by C. lychnitis and (ii) abundance of C. lychnitis, where present. Occupancy of individual V. nigrum plants within occupied patches was also investigated. The likelihood of patch occupancy increased with patch size, and decreased with patch isolation. Abundance of C. lychnitis was negatively correlated with patch isolation and with abundance of the weevil Cionus nigritarsis, which exploits the same host plant and may be a competitor. Within occupied patches, larvae of C. lychnitis were significantly more likely to be found on taller plants with more flower spikes; such plants are typical of established rather than newly-created patches. These results may help to guide efforts to conserve C. lychnitis, highlighting the importance of habitat connectivity and indicating potential management actions to promote features positively associated with larval incidence and abundance.