Of the 25 plus species of butterfly found at the Northern Quarter there are rarer Biodiversity Action Plan (BAP) species such as Small Pearl Bordered Fritillary, Wood White, Grizzled Skipper and Dingy Skipper. These are all nationally declining and are given high consideration for conservation.
In particular the Small Pearl Bordered Fritillary has declined massively in the Forest. In the late 1980's there were over 40 distinct breeding colonies spread throughout the Forest. Since then there has been a catastrophic decline to only two breeding sites in 2013 in spite of active conservation work over the last ten years.
One of these surviving breeding sites is on the centre section of the Linear Park with the Northern Quarter area being a main flight way linkage to former breeding sites and the other surviving colony at Moseley Green. The Northern Quarter development will have an impact on the ability of this species to be able to spread out again once suitable habitat has been recreated either by reinstating sheep grazing or by mechanical and volunteer site management.
The latest position for the Spine road is now right over the breeding area for the Wood White butterfly which is one of the fastest declining UK butterflies with less than 50 breeding colonies in total. The food plant and ride it uses will be decimated by the new road. Around Steam Mills lake there are breeding sites for Grizzled and Dingy Skipper, again fast declining and likely to be at least damaged by any new development.
As well as butterflies the Northern Quarter has a fantastic quota of moths. On one night in August 2012 the Glos moth group recorded the highest number of moths ever recorded in one night in the Dean. Over 150 species of moth in one trapping event. In total the cumulative moth recording now amounts to over 250 species. Not surprising when there are so many bat species present which eat flying insects! this shows how important the site is for it's concentration of wildlife which has been lost from other areas of the Forest.