Scotch Argus (Erebia aethiops)
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© Eddie John
The Scotch Argus lives in well-defined colonies in rough damp or boggy grassland in mountainous or hilly areas in Scotland up to 500m where its main foodplant is Purple Moor Grass (Molinea caerulea). At its only two (dryer) sites in northern England, Blue Moor Grass (Sesleria caerulea) is the main foodplant. The butterfly is often abundant where it occurs. Overall populations and range appear to be stable. (For further details on this species see http://www.butterfly-conservation.org/).
Status details :
Status since 1979 is Stable with a increase of 90%
Status over the last 20 years is Rapid decline with a decrease of -40.4%
Status over the last 10 years is Stable with a decrease of -38.5%
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 collated index is derived from only a few sites but shows a significant positive trend, though increases were in the early years of monitoring when data were primarily from a single site. The collated index indicates that overall populations have remained stable for the majority of the period, but at site level there are big differences. For example at Taynish on the west coast of Scotland there has been a significant decline whereas at Insh Marshes in Highland numbers have increased dramatically in recent years.
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, Scotch Argus has been recorded from 186 transects in the Butterfly Monitoring Scheme. Of these, annual indices of abundance have been calculated from 30 sites, with an average index of 240 individuals per site.
For 14 of these sites, Scotch Argus has been recorded well enough to calculate annual indices of abundance in more years, allowing trends to be calculated.
In 2018, 4396 individuals were recorded from 20 sites, producing annual indices at 10 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
|Extinct sites (1)|
|Stable sites (6)|
|Increasing sites (3)|
|Declining sites (6)|