Dr Lisbeth Horsley explores how moths threatened by climate change could be saved by better water management.
Global climate change is causing species to shift their distributions polewards and to higher elevations 1,2. Most research has focussed on leading (cold) range shifts3–5, and range retractions at species’ trailing (warm) range margins have been more challenging to document. However such populations are at higher risk of extinction under climate change6, therefore understanding what factors are driving distribution changes at warm range edges and in cool-adapted species, in particular, is vital for implementing conservation action.
Lepidoptera have undergone significant changes in distribution due to climate change, particularly at range margins7. Studies have predominantly focussed on changes at the cold range margins of warm-adapted Lepidoptera species, and often only consider temperature as the sole driver of these changes. Around 10% of the macro-moth species in Britain are naturally restricted to cooler temperatures, and most of these moths have declined in distribution over recent decades, perhaps due to their limited ability to track climate change.
New research led by Butterfly Conservation, in collaboration with Northumbria University, used volunteer-collected data from the National Moth Recording Scheme over a 40-year period to identify how cool-adapted moths have shifted their British distributions over time, and whether these changes are linked to temperature and precipitation.
The results find that the warm range margin of cool-adapted moths has retreated polewards and uphill over time, consistent with previous studies on cool-adapted butterflies 8. However, due to topographical features or spatial variation in climate change, we might expect different species to move in different directions in order to maintain their climatic niche. Looking at how species’ range centroids have moved over time reveals that the distributions of cool-adapted moths are indeed shifting in many different directions, with a significant bias towards the north-west. These shifts correlate with climatic changes, providing evidence that species’ distributions are tracking their historical temperature and precipitation conditions.
Some species in the study have become locally extinct, particularly in more southerly and easterly parts of Britain. Temperature is the strongest predictor of such losses, with higher temperatures, both in the past and present, increasing the risk of local extinction for cool-adapted moths. However, when precipitation is also high in these warm areas, extinction risk is reduced, suggesting that species are buffered from local extinction by higher precipitation in areas with high temperature. This is likely to be because the larval host plants of these moths survive better when there is more rainfall.
These results highlight the importance of considering water availability in the landscape as part of climate change adaptation for biodiversity. Changes in management such as reducing overgrazing, increasing tree cover, slowing rivers, and blocking drainage ditches on peatlands could help retain water and benefit moths and other wildlife, as well as increasing carbon capture and reducing flooding. Existing Butterfly Conservation projects such as the Bog Squad, which is re-wetting damaged peat bogs in Scotland, are already providing such benefits but much more is required to protect wildlife and people as the climate crisis grows.
1. Chen I.-C., Hill J. K., Ohlemuller R., Roy D. B., Thomas C. D. (2011) Rapid Range Shifts of Species Associated with High Levels of Climate Warming. Science 333: 1024–1026. https://doi.org/10.1126/science.1206432
2. Parmesan, C., Yohe G. (2003) A globally coherent fingerprint of climate change impacts across natural systems. Nature 421: 37–42. https://doi.org/10.1038/nature01286
3. Hickling R., Roy D.B., Hill J.K., Fox R., Thomas C.D. (2006) The distributions of a wide range of taxonomic groups are expanding polewards. Global Change Biology 12: 450–455. https://doi.org/10.1111/j.1365-2486.2006.01116.x
4. Mason S.C., Palmer G., Fox R., Gillings S., Hill J.K., Thomas C.D., et al. (2015) Geographical range margins of many taxonomic groups continue to shift polewards. Biological Journal of the Linnean Society 115: 586–957, https://doi.org/10.1111/bij.12574
5. Freeman B.G., Scholer M.N., Ruiz-Gutierrez V., Fitzpatrick J.W. (2018) Climate change causes upslope shifts and mountaintop extirpations in a tropical bird community. Proceedings of the National Academy of Sciences 115: 11982–11987, https://doi.org/10.1073/pnas.1804224115
6. Cahill A.E., Aiello-Lammens M.E., Fisher-Reid C., Hua X., Karanewsky C.J., Ryu Hae Yeong, et al. (2014) Causes of warm-edge range limits: systematic review, proximate factors and implications for climate change. Journal of Biogeography 41: 429–442, https://doi.org/10.1111/jbi.12231
7. Mills S.C., Oliver T.H., Bradbury R.B., Gregory R.D., Brereton T., Kühn E., et al. (2017) European butterfly populations vary in sensitivity to weather across their geographical ranges. Global Ecology and Biogeography 26: 1374–85, https://doi.org/10.1111/geb.12659
8. Franco A.M.A., Hill J.K., Kitschke C., Collingham Y.C., Roy D.B., Fox R., et al. (2006) Impacts of climate warming and habitat loss on extinctions at species’ low-latitude range boundaries. Global Change Biology 12: 1545–1553, https://doi.org/10.1111/j.1365-2486.2006.01180.x