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 THE STATUS AND HABITS OF THE
SMALL PEARL-BORDERED FRITILLARY BUTTERFLY
(Boloria selene)
ON SHROPSHIRE AND STAFFORDSHIRE SITES IN 2002

Photo - Peter Boardman


Dr Jenny Joy 

December 2002 

Survey report for English Nature,

Attingham Park,
Shrewsbury,
Shropshire,
SY4 4TW.

 

Acknowledgements

This work was carried as a result of financial support from English Nature (Attingham Park, Shrewsbury) to whom I am very grateful. I would also like to acknowledge the support of Forest Enterprise (particularly Phil Rudlin and Richard Boles at the Wyre Forest) whose enthusiasm helped to carry me through.

I would like to thank the following people: Ruth Edwards, Dean Fenton, Neil and Corinna Gregory, Dave Grundy, Frank and Pat Lancaster, Phil Rudlin, Sylvia Sheldon and Richard Southwell for help with the field survey work, Jim Chance (Butterfly Conservation (BC), West Midlands Branch) for supplying historical records from the BC West Midlands Branch database, Craig Slawson (Staffordshire Records Centre) and Ann Waite (Shropshire Biological Record Centre) for supplying additional county records, Craig Yates for his wealth of records from Staffordshire sites and his comments on possible reasons for declines, James Hill for his records from Consall Wood and his enthusiasm for further recording in the future, Bill Davidson for his recent records from Shropshire sites, Vincent Smith (Staffordshire Wildlife Trust) for his comments on Doley Common, Jan Pursaill (Shropshire Wildlife Trust (SWT)) for allowing me to have access to SWT site files, Phil Rudlin (Forest Enterprise) for his general interest and administrative support of this project, Graham Walker and Jonathan Blowers (English Nature (EN)) for their enthusiasm for plans to now take work on this species a stage further and Sandra Wilson (EN) for sending me the NVC data collected by EN staff at Cannock Chase in July 2002.

I would also like to thank Kate Thorne for undertaking most of the vegetation assessment work, Peter Boardman for his survey of Llynclys Common, all the landowners who gave me permission to go on their land, and Mike Williams and Katherine Stewart (both BC) for their comments on an earlier draft of this report.
 

 

Summary

The Small Pearl-bordered Fritillary continues to exist at a number of sites in Shropshire and Staffordshire. This species is currently known from three areas of Staffordshire (e.g. Cannock Chase and the Churnet Valley) with occasional sightings suggesting there must be at least one more colony yet to be found (in the Gnosall area). In Shropshire, the Small Pearl-bordered Fritillary occurs in many more areas (Wyre Forest area, Stiperstones area, Clun Forest area, Catherton Common Area) and sites (e.g. Llynclys Common) and may be much more extensive than envisaged in the early 1990's as there are numerous wet flushes on remote hillsides in south Shropshire which may well support marsh violet and which have yet to be explored. In the Wyre Forest, the results from two butterfly transects suggest that this species has been fairly stable since 1989 although it does have occasional peaks and troughs.

Most colonies in Shropshire and Staffordshire are small (88%) with only four sites supporting medium sized colonies. Interestingly, all the Wyre Forest sites only supported small colonies even though this species is widespread in the forest. One problem with the survey of the Wyre Forest for the Small Pearl-bordered Fritillary was the lack of consistent recording. It was possible to record several adults in one place on one visit then to find no adults at all during a subsequent visit. This finding suggests that this species may roam quite widely within the forest as they search for suitable habitat patches. These results have implications for site management as they suggest that all suitable habitat patches created within a forest or area could be reached and that the system may be a 'metapopulation' with areas of suitable but unoccupied habitat.

In Shropshire and Staffordshire most Small Pearl-bordered Fritillary colonies are likely to be utilising marsh violet as the main larval foodplant. The main exceptions here are the Wyre Forest and Llynclys Common in Shropshire where only dog violet is abundant. It is also not yet known which foodplants are likely to be utilised in the Churnet Valley in Staffordshire as marsh violet and dog violet may both be present. Interestingly, the vegetation communities of the Small Pearl-bordered Fritillary nectaring areas in the Wyre Forest are the same as those identified on mire sites supporting the Small Pearl-bordered Fritillary elsewhere in Shropshire but in the Wyre Forest these communities have no marsh violet.

On occupied sites with marsh violet, on average, marsh violet was present in over 20% of the flight area, a large proportion of this marsh violet was in exposed locations (mean 30%) and it was sometimes associated with Sphagnum (mean 26%), dead grasses or litter (mean 17%) and with distinct grass clumps (mean 22%). On the small number of un-occupied sites visited, marsh violet was still common in the likely flight area (mean over 30%) but much less of it was in exposed locations (mean 13%) and more of it was associated with Sphagnum (mean 43%) rather than with dead grasses or litter (mean 3%) or distinct grass clumps (mean 11%). In general, there was limited tree or scrub growth within areas where marsh violet were present.

There are many sites on Shropshire and Staffordshire where additional management may be beneficial to the Small Pearl-bordered Fritillary. On sites where mire communities are present, it is essential that these sites adopt/continue a system of periodic grazing to both preserve the floristic diversity and to prevent further reversion to scrub. Cattle and/or horses are better suited to wet ground and cattle were present on a number of the sites. Where grazing regimes are uncertain it is difficult to recommend a best time for grazing. Since grazing is likely to be unsuitable by late autumn/early winter due to the increased wetness of the ground, grazing should perhaps be in place from some time in July but this is something that would need to be monitored. While the options for bracken control in the Wyre Forest are also discussed, it is difficult at present to recommend any specific bracken management for the Small Pearl-bordered Fritillary here as only one breeding areas for this species has been identified. There is however, no doubt that the maintenance of the open wet flushes is also important for this butterfly in the Wyre Forest even though grazing may not be a viable option here.

In the Wyre Forest, the vegetation communities of nectaring areas were identified to be M23 and M25. The vegetation communities of three likely breeding sites were W25 (on two occasions) and U20 (on one occasion) with one confirmed breeding area being U20. Elsewhere, the M23 and M25 vegetation communities were present on two other Shropshire sites where breeding was confirmed in 2002. Six other NVC communities (M6, M15, M21, M23, M24, M25) were identified in areas of Shropshire and Staffordshire where the Small Pearl-bordered Fritillary still occurs with M23 being the community most frequently present. Three of these six NVC communities (M6, M23 and M25) were present on apparently un-occupied sites with two additional communities ( W4 and H4) perhaps suggesting why they are not occupied.

Priorities for further work on the Small Pearl-bordered Fritillary sites in Shropshire and Staffordshire should include annual monitoring of at least five key sites by timed counts, further survey work for adults and identification of breeding habitats and continued liaison with landowners and land managers.

If you would like to read the full report of this project please contact Jenny Joy on 01952 249325 or write to The Croft, Off Haygate Road, Wellington, Telford, Shropshire, TF1 2BW.


 

 

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