Rare moth survey in Avon Gorge reaches 10-year milestone

A survey of a rare moth found only in the Avon Gorge in this country, is celebrating its 10th year.

Since 2011 Bristol Zoological Society has carried out an annual survey of the silky wave moth during their flight season, which takes place from June to early July. 

Dr Jen Nightingale, UK Conservation Manager, said: “This survey is critical as it helps us to understand if the management of this area is working well for this species. 

“We can then use the silky wave moths as an indicator species, to know if the habitat is suitable for other species at the site as well.”

In the coming weeks a team of nine people will be tracing paths in 13 different sites on both sides of the gorge.

They will follow timed routes tapping either side of their path lightly with a walking stick to create a disturbance, which causes the white-winged moths to fly. Once a sighting is confirmed the moth is added to the count.

Dr Nightingale said: “We walk the same transects every year, count the moths and record the temperature, the wind speed and other environmental details.”

In the 2020 survey, which went ahead under COVID-19 restrictions, 342 silky moths were recorded during the species’ peak flight week.

The survey team will begin visiting the silky moth sites in Avon Gorge, including Black Rocks, at around breakfast time on specific days in the coming weeks, spending between three and five hours a day counting moths.

Bristol Zoological Society works with Butterfly Conservation, the National Trust, Bristol City Council and the Avon Gorge and Downs Wildlife Project to conduct the survey each year.

Dr Nightingale said: “This is a useful exercise because it helps to inform the management of the sites as we are looking at several elements of their habitat, including number and types of other flying insects and vegetation.”

The moth numbers were monitored on an ad hoc basis from 1992 until 2011 by Butterfly Conservation and Bristol Zoological Society. In 2011 Bristol Zoological Society officially took over the annual monitoring of the sites.

The silky wave moths were first found in the Avon Gorge in 1851 and are known to live in only two other places in Great Britain -- the Gower coast of Glamorgan and on the Great Orme in North Wales -- but they are more commonly found in central and southern Europe, northern France and Germany.

Dr Nightingale said: “They are at the very edge of their range here and this is an important survey. We have a duty to ensure their survival into the future.”

Conservationists from Bristol Zoological Society are involved in helping safeguard species of animals in this country and across the world.

In the UK they are working to re-introduce white clawed crayfish into West Country rivers and they are involved in 14 projects in 10 countries to help save animals, including giraffes and lemurs, whose futures are threatened.

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