Pearl Bordered Fritillary (Boloria euphrosyne) History Relatively recent records (from the 1970’s up to 1988 ) seem to suggest that the PBF was most probably an uncommon butterfly on the Welcombe/Marsland Nature Reserve. Data from around this time indicates that there were ‘small numbers on the overgrown rides and glades running throughout the woodland’. Prior to any organized conservation management (and before the woodland became a nature reserve) most of these old ‘access areas’ were covered in scrub,bramble and gorse.The previous 100 years or so had witnessed a considerable amount of cutting and felling in many sections of the woods, mainly by previous owners. Undoubtedly, the PBF would have been a much commoner butterfly in those days perhaps present in very large numbers in the newly coppiced areas. The cessation of this type of management led to a slow decline in the PBF populations but some areas would still have retained small numbers as indicated above. One such area was known as ‘Hard Hills’ – a 15 acre west-facing slope (can be very hot in spring/summer) dominated by gorse and bracken (SS 235176).This area had historically been grazed by sheep/goats but this ‘management’ had ceased some 40 years (before 1981).Some periodical burning of the slopes after the grazing had resulted in a dense bracken layer and yet the herb layer underneath ‘was comparatively diverse’. The first management plan in 1976 suggested that the area ‘be cleared of scrub and the bracken be cut and /or chemically treated’ . Although some minor work had been carried out in the mid 70’s the first real work programme began in 1980.All the work was documented on a card index system: 1 ‘In March of 1980 the whole of the slope was burnt… and the experiments with spraying continued throughout the spring and summer.. applying Asulux with a hand held ultra low volume sprayer….In 1981 the results….became apparent…the spraying having been 90% effective….the flush of flowers was remarkable…amongst many other species of flower the ground was carpeted with violets and bugle….a butterfly transect was set up in the area…the most startling and obvious increase was in …the Pearl and Small Pearl Bordered Fritillary…’ Hard Hills in 1981 after winter burning. Gorse/bracken regrowth up to 1987. Many other species of butterfly benefited from the management in the area.These included Marbled White, Dark Green Fritillary and, in the early 90’s, High Brown Fritillary. Grizzled Skipper was recorded for a number of years. (see appendices for details). From 1985-1988 the site was managed less intensively resulting in a mosaic of re growth gorse and bracken but with an increasingly diverse sward in the more open areas. (A full flora list can be found in the appendices along with other species lists). Following on from the experience at Hard Hills other areas were worked in a similar manner. The majority of the work consisted of rotational cutting of scrub/bracken/gorse although some sections of hazel coppice was reinstated on parts of the reserve. 2 The main PBF sites and their management. These areas occur in c53 (Hard Hills), part c17 (SS 224173 Travel Bridge Meadow), part c15 (SS224175 Broad Arbor), c119,part c1 and c25 (clearings).The main breeding colony occurs in c53 and its management is detailed below. C53-Hard Hills In 1988 much of the slope was covered in bracken and gorse. It was decided to put the whole of the left hand section onto a ‘coppice’ rotation with areas being cut/raked each during the late summer and throughout the winter period. The ground underneath the cut vegetation (especially the gorse) was very bare to begin with but yielded masses of primroses, violets and bugle in the following spring and even more during the second year. On occasions the cleared ground had to be raked in order that the thick layer of dead material didn’t inhibit the regrowth of the violet/bugle community. The raked material was stacked in vegetation piles which over the years rotted down – these newly created habitats became very good areas for various species especially spiders and grass snakes. The bottom section of HH1 ( section a) was/is cut every winter with HH2 (section b) being cut every other winter. Other sections were put on rotation. Example of management card showing main areas of work along with notes. Newly cleared gorse with first year flush of primroses ,violets and bugle. 3 Extensions to these two main areas have been made over the years with management being on an ‘ad hoc’ basis (original maps showing extensions can be seen on the left). These areas are cut/raked when the ground flora and especially any grass species, seems to be increasing i.e. areas are always kept at the initial growth stage with large sections of bare ground interspersed with a mosaic of ‘brown’ vegetation- ( usually dead bracken or ‘unraked’ cut bracken which seems from my personal observation to be a preferred egg laying material for the PBF).In short the PBF need open, hot and freshly cut areas which remain bare for a season or two and yet retain a lush covering of both violets and bugle. In almost all of the egg laying data observations the females have preferred these areas. It seems to be beneficial to the PBF’s if some areas of gorse/scrub are left next to the ‘bare’ areas in order to afford some shelter. Some bracken sections are cut monthly during the season in order to create open areas for the butterflies to use. Dark Green Fritillaries especially have been noted to lay on and around these areas. Hard Hills #1 showing initial management at front. The left hand side gorse is on rotational cut. The right hand side (only one third in photo) is entering rotation. The cut gorse/scrub is burnt with some stumps being treated (c10%).Some re growth is cut back year on year until eventual dieback. If the tractor is used for cutting, the height of the swipe blade is controlled (at about 3 to 4 inches) and never allowed to drop right down to ground level. Areas cut with a clearing saw use the same principle. The great majority of this cutting takes place during the autumn/winter period. The picture on the left shows the ground after cutting .Only one or two violets can be seen. 4 The picture on the left shows the same ground during the following spring/summer. The increase in violets is obvious and such an area presents an ideal breeding habitat for the PBF butterfly. The picture on the right shows a single egg laid on violet. Other PBF areas The other areas on the reserve are managed in a similar way to that of Hard Hills. The only exception occurs in part of the reserve known as Long Meadow where some hazel coppicing has been carried out. Although some smaller areas of hazel have been taken out at HH#1, the clearings in c25 and in Travel Bridge Coppice. C34 coppice section. Some notes: On reserve the first PBF emergence occurs usually in the last week of April into the first week of May. Example details below. YEAR FROM TO NUMBER OF DAYS 1994 29 April 29 May C30 1995 30 April 12 June C43 1996 30 April 13 June C44 1997 15 April 30 May C45 1998 8 May 18 May C10 1999 29 April 26 May C27 2000 1 May 22 May C22 The preferred nectaring plant is bugle. If any buttercups are flowering later in the flight period they will use these as the bugle goes over. If emergence is early and bugle is scarce the butterflies will nectar on Lesser Celandine and Dandelion. Females have been noted laying frequently on the violets growing within sheltered areas created by the cut gorse/scrub which has had one or two seasons to re grow (see picture left below) . Other plants growing after the second season (picture right) 5 An accidental burn occurred at the top of HH#1 in 1999 but few individuals were recorded here during the following season. In 2002 violets were recorded growing more vigorously and in 2003 PBF’s were in record numbers here (see below) The butterfly transect runs at the bottom of the slopes at Hard Hills alongside the path but has been extended to take in the newly cut areas. Some data for the PBF is based on timed field counts. Details can be found on ‘Recorder’ computer data files. PBF Peak Counts 1988-2000 200 185 180 160 140 120 113 100 86 83 Abundance 80 67 64 57 60 51 50 45 36 40 24 19 20 0 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 Graph showing peak counts of PBF from 1988-2000 PBF Indices 1988-2000 400 367 350 300 250 197 200 150 143 143 150 138 124 108 93 100 83 67 60 50 33 0 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 Graph showing indices of PBF from 1988-2000 In 1997 Dr. Tom Brereton from Butterfly Conservation monitored and recorded PBF on a number of sites in Devon and Cornwall including Marsland reserve. The following data shows the number of individuals counted in a timed period during the flight period (date and times of day vary) : SITE NUMBER OF PBF TIME (MINS) NOTES A 8 60 B 1 50 C 40 45 D 1 75 E 4 15 F 40 100 G 6 70 H 1 30 6 J 15 105 K 10 60 L 38 300 Large site M 14 105 Broad Arbor c15 29 3 Reserve 23 April C25 Clearings 93 8 Reserve 23 April C17 Long meadow 22 5 Reserve 23 April Hard Hills 81 7 Reserve 1 May(timed count by TB / actual transect count was 96) The information below shows the site area code on reserve with recording dates/year 1988-1997 and numbers of PBF.Hard Hills is code 1/53/1, Travel bridge 1/17 and 1/34, clearings 1/25 and Broad Arbour 1/15.