Gatekeeper (Pyronia tithonus)
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© Nick Greatorex-Davies
The Gatekeeper is a common species of sheltered grassland such as adjacent to scrub, along hedgerows, woodland edges and rides where its larvae feed on a range of fine and medium-leaved grasses. 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 decline with a decrease of -43.7%
Status over the last 20 years is Rapid decline with a decrease of -51.3%
Status over the last 10 years is Stable with a decrease of -6.6%
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 show no significant long-term trend indicating overall stability in numbers, although more recently there has been a significant short-term decline. There have been large fluctuations in abundance over the monitoring period in an apparently cyclic fashion. There is often a high degree of synchrony in fluctuations between sites across the country indicating that weather conditions have a particularly strong impact on this butterfly. In the years 1985-88 the butterfly experienced a huge decline following its then highest index of the series in 1984, but this was followed by three years of increase that took it to a well above average level. This decline and increase corresponded well with a decline and increase of several other species of the browns (Satyrinae).
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, Gatekeeper has been recorded from 799 transects in the Butterfly Monitoring Scheme. Of these, annual indices of abundance have been calculated from 914 sites, with an average index of 176 individuals per site.
For 438 of these sites, Gatekeeper has been recorded well enough to calculate annual indices of abundance in more years, allowing trends to be calculated.
In 2017, 89986 individuals were recorded from 536 sites, producing annual indices at 425 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 (6)|
|Stable sites (464)|
|Increasing sites (84)|
|Declining sites (188)|