Lulworth Skipper (Thymelicus acteon)
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© Eddie John
The Lulworth Skipper has a very restricted distribution in Britain. Where it occurs it can be locally very abundant in tall unmanaged calcareous grassland where its foodplant Tor Grass (Brachypodiun pinnatum) grows in abundance. (For further details on this species see http://www.butterfly-conservation.org/).
Status details :
Status since 1992 is Rapid decline with a decrease of -76.6%
Status over the last 20 years is Rapid decline with a decrease of -76.5%
Status over the last 10 years is Stable with a increase of 216%
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 :
This rare and localised species is found at a limited number of sites in south-west England. Although the numbers on these sites can be very large there has been a significant decline since monitoring began. More worryingly this decline has continued and the the short-term trend is of an even more significant decline. High indices in earlier years were probably when the main sites supported more areas of tall grassland where Tor Grass was dominant. A number of these sites have since been managed (more heavily grazed) to produce a shorter sward, primarily for the Adonis Blue.
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, Lulworth Skipper has been recorded from 90 transects in the Butterfly Monitoring Scheme. Of these, annual indices of abundance have been calculated from 14 sites, with an average index of 110 individuals per site.
For 6 of these sites, Lulworth Skipper has been recorded well enough to calculate annual indices of abundance in more years, allowing trends to be calculated.
In 2018, 640 individuals were recorded from 8 sites, producing annual indices at 7 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 (1)|
|Stable sites (3)|
|Increasing sites (1)|
|Declining sites (4)|