Marbled White (Melanargia galathea)
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© Nick Greatorex-Davies
The Marbled White is a mostly southern species in Britain occurring in well defined colonies in tall open unimproved calcareous, or sometimes neutral, grassland where its main larval foodplant, Red Fescue (Festuca rubra), grows in abundance. The butterfly is expanding its range in Britain. (For further details on this species see http://www.butterfly-conservation.org/).
Status details :
Status since 1976 is Rapid increase with a increase of 60%
Status over the last 20 years is Stable with a decrease of -6.3%
Status over the last 10 years is Rapid increase with a increase of 120%
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 indices have shown large fluctuations in abundance and there is a high degree of synchrony between many sites. Accounting for these fluctuations the overall trend shows a non-significant increase in abundance over the whole monitoring period, although more recently there has been a decline. The butterfly is expanding its range in parts of Britain, probably in response to climate change, and at many sites there have been significant increases in abundance. In addition several sites have been colonised.
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, Marbled White has been recorded from 586 transects in the Butterfly Monitoring Scheme. Of these, annual indices of abundance have been calculated from 625 sites, with an average index of 92 individuals per site.
For 309 of these sites, Marbled White has been recorded well enough to calculate annual indices of abundance in more years, allowing trends to be calculated.
In 2017, 46111 individuals were recorded from 332 sites, producing annual indices at 277 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 (17)|
|Extinct sites (2)|
|Stable sites (243)|
|Increasing sites (138)|
|Declining sites (67)|