Speckled Wood (Pararge aegeria)
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© Nick Greatorex-Davies
The Speckled Wood is a true woodland butterfly preferring the dappled shade of partially shaded woodland. Its caterpillars feed on a range of coarse grasses including Wood False Brome (Brachypodium sylvaticum) and Cock's-foot (Dactylis glomerata). The species has been expanding its range since the early to mid 1900s. (For further details on this species see http://www.butterfly-conservation.org/).
Status details :
Status since 1976 is Rapid increase with a increase of 76%
Status over the last 20 years is Stable with a increase of 27%
Status over the last 10 years is Stable with a decrease of -5.3%
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 trend for the Speckled Wood shows a highly significant and generally steady increase. The butterfly has a divided distribution in Britain (it occurs throughout Ireland) and it has continued to colonise new areas in both parts of its range during the monitoring period. This range expansion is particularly apparent in eastern England and at least 20 UKBMS sites have been colonised since they started being monitored, the majority in this area. The increase in abundance can be largely accounted for by these colonisations. At the majority of other sites where the butterfly already occurred, populations have mostly remained fairly stable over the monitoring period.
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, Speckled Wood has been recorded from 829 transects in the Butterfly Monitoring Scheme. Of these, annual indices of abundance have been calculated from 948 sites, with an average index of 72 individuals per site.
For 462 of these sites, Speckled Wood has been recorded well enough to calculate annual indices of abundance in more years, allowing trends to be calculated.
In 2016, 40923 individuals were recorded from 559 sites, producing annual indices at 426 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 (35)|
|Extinct sites (1)|
|Stable sites (499)|
|Increasing sites (163)|
|Declining sites (72)|