The Wall Brown butterfly, last seen at Raw Nook Nature Reserve in 2009, was discovered by Martyn Priestley, field officer for the Low Moor and Oakenshaw Wildlife Conservation Group.
The rare sighting in Low Moor could indicate a small but hopeful change for the Wall Brown, a butterfly that has suffered long-term decline nationally and is classified as a priority conservation species by the UK government.
Mr Priestley said: “I was showing a conservation group around the area and one of the party said ‘oh, what’s this butterfly?’
Raw Nook Nature Reserve (Image: Martyn Priestley)
“I looked at it in disbelief. Straight away I said, it’s a Wall Brown.
“It’s unbelievable to be honest.”
Last sighting in 2009
Mr Priestley later checked his records and confirmed it had been 17 years since the butterfly was last seen in the area.
He said: “I knew it was probably sort of 20 years.
“I came back and looked at my records and it was the June 24, 2009 last sighting.
“Prior to that, it bred regularly but it’s in real trouble at the moment.
“The other good news was that it was completely fresh, which suggests it’s newly emerged from a caterpillar.”
He said further work was needed to establish whether the species was breeding in the area again.
Conservation work ‘a lifelong passion’
Mr Priestley has been recording wildlife at Raw Nook for 50 years and has built a large database covering butterflies, insects and birds.
His work in the area is part of a long-running effort to boost urban biodiversity.
He said: “It’s a lowland heath habitat down there, which is quite rare in an urban environment.
“We do work down there purely for all the biodiversity.
“Everything’s for wildlife, to make the area better – and it’s proven it.”
Urban reserve is ‘gem for biodiversity’
The Wall Brown’s return is particularly significant given the reserve’s location surrounded by industry in South Bradford.
Mr Priestley said: “It’s a real gem for biodiversity in an urban setting.
“It just illustrates how important these sort of areas are.”
The Wall Brown is identifiable by its pale orange and brown colouring and distinctive pattern of black eyespots on its wings. (Image: Pixabay)
He said he was “baffled” by the butterfly’s sudden return.
The discovery, he said, underlines the critical value of urban nature spaces.
Mr Priestley said: “People shouldn’t have to get in cars and travel for miles to see wildlife.
“These urban nature reserves are vastly, vastly important for biodiversity in the area.
“I think it shows that nature can work alongside industry.”