Essex Skipper (Thymelicus lineola)
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© Nick Greatorex-Davies
The Essex Skipper occurs in self-contained colonies in tall dry grassland in open sunny situations. The butterfly mainly uses Cock's-foot (Dactylis glomerata) or Creeping Soft Grass (Holcus mollis) as hoodplants, but several other grasses are sometimes used. The butterfly is currently expanding its range northwards and westwards from south-east England. (For further details on this species see http://www.butterfly-conservation.org/).
Status details :
Status since 1977 is Rapid decline with a decrease of -89.6%
Status over the last 20 years is Rapid decline with a decrease of -80.7%
Status over the last 10 years is Stable with a increase of 57%
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 indices for this species and the similar Small Skipper are based on transect data only where reliable separation of the two species has been made. Difficlt to separate in the field whilst walking transects, one suitable method is to catch a given number of Thymelicus spp in each different habitat on the transect, identify and release them and calculate the proportion of each species in that section. Becasue the flight periods are slightly different it is important this is done each visit. Although this can be time consuming it gives much more information about two species which may be showing different trends, which has been the case in some years. Without such information we cannot reliably measure the status of each species. Essex Skipper has declined on monitored sites since monitoring began, though not significant until more recently - the short-term trend is of significant decline with several extremely low indices in the last decade or so.
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, Essex Skipper has been recorded from 420 transects in the Butterfly Monitoring Scheme. Of these, annual indices of abundance have been calculated from 340 sites, with an average index of 0 individuals per site.
For 0 of these sites, Essex Skipper has been recorded well enough to calculate annual indices of abundance in more years, allowing trends to be calculated.
In 2017, 1324 individuals were recorded from 102 sites, producing annual indices at 86 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 (11)|
|Extinct sites (7)|
|Stable sites (128)|
|Increasing sites (16)|
|Declining sites (48)|