Marsh Fritillary Survey
Where damp and tussocky, chalk, or short coastal grassland within their known geographic range is deemed likely to be affected by project proposals, a marsh fritillary survey may be required, which aims to establish presence/ likely absence of marsh fritillary on site, and identify potential for constraints and opportunities.
Marsh fritillary are typically found in damp and tussocky, chalk, or short coastal grassland, and large woodland clearings throughout parts of western Britain, though populations are often scattered and at low density. The British population declined dramatically during the 20th century, primarily due to habitat loss and degradation. They are protected under UK and European law, making it an offence of kill, capture, or disturb them, or to damage any site known to support them, regardless of whether they are currently present. Works affecting marsh fritillary are subject to licensing procedures.
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The appraisal is used to inform the emerging scheme design, enabling significant ecological effects within the zone of influence to be avoided, mitigated, or compensated for, where necessary. This ensures the continued favourable conservation status of marsh fritillary, post development, and ultimately compliance with nature conservation legislation and planning policy.
Presence/ likely absence surveys typically comprise three elements: searches for adult butterflies; botanical surveys; and larval web inspections. Searches for adult butterflies involve traversing the site, and sampling distinct patches of habitat throughout the survey area. Botanical surveys target the key larval foodplants of marsh fritillary - devil's-bit scabious, and to a lesser extent field scabious and small scabious. An update appraisal of the site's suitability to support breeding marsh fritillary during the optimal season will be undertaken simultaneously. The larval web inspection comprises a systematic search of any areas of habitat supporting the key larval foodplants. The site survey is typically supplemented by a desk study, utilising maps and aerial photographs of the surrounding area to identify ecological connectivity, and published records of marsh fritillary, purchased from the local records centre.
Requirements for any necessary avoidance, mitigation, or compensation measures will be identified, and opportunities for ecological enhancement will be outlined, to integrate on-site biodiversity net gain into the scheme at an early stage, where possible.​ If the proposals are deemed likely to adversely affect marsh fritillary, a mitigation licence may be required, prior to the commencement of works.
Marsh fritillary surveys are seasonally constrained and protracted, making it prudent to plan ahead and consider ecological issues early on in the planning process. A robust marsh fritillary survey at an early stage in project planning and design can therefore deliver significant benefits, avoiding potentially costly and time-consuming delays.​
When
Adult butterfly searches must be undertaken between late May-mid June inclusive, while botanical surveys are undertaken between late July-mid September inclusive. Larval web inspections are ideally undertaken between late August-September inclusive, though survey between early August-early October inclusive is permissible.
Why Us
With over fifteen years' experience in undertaking ecological surveys, mitigation design, licensing, site supervision, and monitoring, our team of expert ecologists can help guide your project through the planning process.
Our licensed ecologists can appraise your site's marsh fritillary suitability, undertake surveys, design mitigation strategies, and apply for mitigation licences.
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By working closely with our clients, we ensure that their developments progress smoothly and in full compliance with the law, orchestrating the best possible outcome for them and the natural world.
