Grizzled Skipper (Pyrgus malvae)
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© Nick Greatorex-Davies
The Grizzled Skipper is a very localised and declining butterfly in Britain occuring in discrete colonies in open, sunny but sheltered, unfertilised grassland, woodland rides and glades or abandoned industrial sites, breeding where the vegetation is sparse and there are patches of bare ground. Best sites occur where there is a mosaic of short and long vegetation where the caterpillars feed on rosaceous plants such as Wild Strawberry (Fragaria vesca), Creeping Cinquefoil (Potentilla repens) and bramble (Rubus sp.). (For further details on this species see http://www.butterfly-conservation.org/).
Status details :
Status since 1976 is Rapid decline with a decrease of -54.2%
Status over the last 20 years is Stable with a decrease of -29.6%
Status over the last 10 years is Stable with a decrease of -42.7%
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 :
The Grizzled Skipper has shown an almost cyclic pattern of declines and increases over the monitoring period. Until recently the long-term trend was of significant decline for this UK BAP priority species, even with the unexpectedly high index in 1997. More recently the Grizzled Skipper has fared rather better on monitored sites, showing a substantial though not significant increase in the last decade or so, and the population is classed as stable since 1976. Sites showing the greatest declines have been woodlands where increasing shadiness and the lack of suitable open areas with sparse vegetation is likely to be an important factor. Brownfield sites are another important habitat for this species.
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, Grizzled Skipper has been recorded from 390 transects in the Butterfly Monitoring Scheme. Of these, annual indices of abundance have been calculated from 385 sites, with an average index of 8 individuals per site.
For 188 of these sites, Grizzled Skipper has been recorded well enough to calculate annual indices of abundance in more years, allowing trends to be calculated.
In 2018, 1146 individuals were recorded from 128 sites, producing annual indices at 91 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 (8)|
|Extinct sites (7)|
|Stable sites (122)|
|Increasing sites (18)|
|Declining sites (44)|