Moth condition: New report shows UK moths are down by a third

A new report on the UK State of Larger Moths from the Butterfly Conservation charity in partnership with Rothamsted Research and the UK Center for Ecology and Hydrology shows a worrying 33% decline in the UK’s larger moth populations over the past 50 years.

The report, the last of which was published in 2013, draws on tens of millions of records collected through the Rothamsted Insect Survey and the National Moth Recording Scheme. The report shows that the total number of larger moths in the UK decreased by 33% over a 50-year period between 1968 and 2017. This decline was seen across the UK, with a greater loss in the south (39% decrease) than in the north of the UK (22% decrease).

Why is that important?

Dr. Richard Fox, Assistant Director of Recording and Monitoring at Butterfly Conservation and lead author of the report, said, “This decline is worrying as moths play an important role in our ecosystems. They are pollinators of many plants, with some wildflowers like orchids relying on visiting moths for reproduction. They also provide essential nourishment for thousands of animal species, including bats and many familiar birds. We are fortunate to have nearly 900 species of larger moths in the UK (including micromotives in the UK which has a total of 2,600 species). As the moths wane, we can be fairly certain that other wildlife is also in decline and our environment continues to deteriorate. “

Oleander Hawk-Moth, Copyright Alan Lewis, from the Surfbirds Galleries

The causes of the decline are mixed, although the common factor is human activity. Habitat destruction and degradation as a result of changes in land management and chemical pollution are believed to be major causes. More sympathetic management (e.g. through agri-environmental measures) often leads to an increased frequency and species richness of moths. Artificial light at night also has a negative impact on individual moths and of course climate change is a big factor.

In warmer climates, species in southern regions tend to expand further north, while moths adapted to cooler climates experience a decline. An example of this is the Gray Mountain Carpet, the prevalence of which has decreased by 81%.

Stopping or reversing species decline is a daunting task, but not impossible. The report contains numerous examples of the success of the conservation of very rare and threatened moths. The work of Butterfly Conservation, its partners and volunteers in recent years has shown real results in reversing species that are critically endangered.

Dan Blumgart, Quantitative Moth Ecologist at Rothamsted Insect Survey, says, “When you compare the larger moths in this newest state of the UK to the first edition in 2006, it’s a disappointment that the situation has not improved. It is clear that a much bolder policy of habitat protection and restoration will be required if British moths are to continue to thrive. “

Dr. Colin Harrower, geospatial analyst at the UK Center for Ecology and Hydrology, says: “Our analysis of the millions of records has shown that four times as many species of moths have declined and increased in abundance over the past 50 years. It is possible that our rarest species, for which we cannot readily establish reliable trends, are at an even greater threat to their populations. “

Read the full report on the condition of the moths here.

To find out how you can help improve the future of moths and butterflies, visit our How You Can Help page for more information.

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