‘Moths are declining rapidly in the UK’ was, unsurprisingly, the message from the State of Britain’s Larger Moths report launched last Friday by Butterfly Conservation. In a week when the controversial topic of bees and neonicotinoids was headline news, it was interesting to hear about the fates of a different group of pollinators.
Two thirds of 337 species of common and widespread larger moths declined between 1968 and 2007, with specialist species tending to fare the worst. In contrast to abundance, the number of species has actually increased, with colonisations outpacing extinctions in Britain.
One thing that was very striking was the difference between north and south. The abundance of moths has not changed in the north; the losses in some species had been offset by increases in others. In the south, however, moth abundance decreased by a staggering 40%.
This striking difference is likely to be partly due to climate change and habitat loss. For the moment at least, climate change is actually beneficial, overall, for UK moths, and the northern species have the greatest benefit. This is in contrast to loss of habitat, which is particularly affecting southern Britain. The loss of semi natural habitats, such as grasslands, has been a cause of decline for many species.
Although insects make up the majority of global animal biodiversity, little is known about their trends, partly because of the challenges of collecting the data. Compared to many insects, Britain’s larger moths are relatively easy to study.
Most species come to light, so it is possible to set up a light trap, leave it running overnight, and count all the moths within it each day. Much of the data for this report comes from the Rothamsted Insect Survey, which has been running continuously for the 40 year period the report covers. Thankfully, the news at the launch was that the Survey’s shaky future seems more secure, with funding confirmed for the next 5 years.
Time to ensure the security of the moths…