Small Pearl-bordered Fritillary (Boloria selene)
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© Nick Greatorex-Davies
The Small Pearl-bordered Fritillary was once widespread in Britain occurring in woodland clearings, damp grassland, heaths and dunes and other damp habitats where its foodplants, mostly Dog Violet (Viola riviniana) and Marsh Violet (Viola palustris), grew. With the demise of coppicing and intensification of agriculture the species has disappeared from many of its former sites becoming scarcer throughout its range, and it is now extinct in nearly all of central and eastern England. (For further details on this species see http://www.butterfly-conservation.org/).
Status details :
Status since 1976 is Rapid decline with a decrease of -68.0%
Status over the last 20 years is Stable with a increase of 19%
Status over the last 10 years is Stable with a decrease of -21.8%
Log collated index plot
This chart shows the index of abundance (LCI = Log Collated Index) over time. It shows fluctuations in
populations from year to year, and is scaled so that the average index over the whole series is equal to 2
(horizontal line). For greater detail about how this index is derived, click on the green question mark above.
Trend description :
Despite being the third most widespread fritillary recorded on UKBMS transects, the overall trend for this species has been a highly significant decline. The main declines were in the early years of the scheme and were followed by a long period of stability from 1982 to 1997. Since 1997 the collated indices indicate a further decline in numbers but more recently Small Pearl-bordered Fritillary abundance has stabilised on monitored sites thanks in part to appropriate habitat management at a number of sites. Although this species has not declined as much as the closely related Pearl-bordered Fritillary the same main drivers are likely to be behind its decline: habitat degradation and loss and isolation of remaining often small, and therefore vulnerable, colonies.
This map shows the distribution between 1995 and 2016. Data is derived from the Butterflies for the New Millenium dataset via the NBN Gateway
This chart shows the average number of butterflies seen on transects between Arpil and October across all sites (fitted values from a Generalised Additive Model). The blue line gives average counts over the full BMS series (1976 to date) and the red line gives the average for the last year.
This map shows symbols for the mean abundance at transect sites, with the colour of the symbol reflecting the level of abundance. Means are over all years. Grey background squares are the occupied cells as shown by the Butterflies for the New Millenium over the previous ten year period.
In total, Small Pearl-bordered Fritillary has been recorded from 297 transects in the Butterfly Monitoring Scheme. Of these, annual indices of abundance have been calculated from 233 sites, with an average index of 25 individuals per site.
For 104 of these sites, Small Pearl-bordered Fritillary has been recorded well enough to calculate annual indices of abundance in more years, allowing trends to be calculated.
In 2019, 2813 individuals were recorded from 76 sites, producing annual indices at 62 of these.
Links to counts
This map shows the trend in abundance at particular transect sites for which data has been received within the last five years. Trends (increasing, declining or stable) are assessed at sites where the species has more than five years of annual index data. Use the option boxes below to view plots for individual sites.
Links to lists of sites with particular statuses
|Colonised sites (4)|
|Extinct sites (6)|
|Stable sites (65)|
|Increasing sites (15)|
|Declining sites (36)|