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Soprano pipistrelle trends for England

England-level population trends for soprano pipistrelle in England from the Field Survey and the Roost Count are shown on this page.

Populations trends for soprano pipistrelle are also produced for Great Britain and Scotland. There are insufficient data to calculate a population trend for this species in Wales.


Field Survey

England index of soprano pipistrelle population from Field SurveysSoprano pipistrelle bat field trend England

Note: The graph above shows the unsmoothed index value for each year (green crosses), the smoothed trend (solid line) and 95% confidence intervals (dotted lines). The smoothed trend for 2016 is shown as a dashed line to indicate that it is provisional.

The smoothed index is currently 32.7% above the 1999 base year value, equivalent to an annual increase of 1.7%. After a slight decline the smoothed index increased steadily between 2002 to a peak in 2010, at which time it was significantly higher than the baseline year. After 2010 it has been somewhat stable, although widening confidence limits mean that currently the smoothed index does not differ significantly from the 1999 baseline value. There are no significant differences between trends for regions within England.

Data from 515 sites contribute to the trend analysis in England.


Roost Count 

England index of soprano pipistrelle population from Roost Counts

Soprano pipistrelle bat roost trend England

Note: The graph above shows the unsmoothed index value for each year (green crosses), the smoothed trend (solid line) and 95% confidence intervals (dotted lines). The smoothed trend for 2016 is shown as a dashed line to indicate that it is provisional.

The smoothed index is currently 50.1% below the 1999 base year value, equivalent to an annual decrease of 4%. There has been a significant decline in the smoothed index since 1999. However it is likely that this species' frequent roost switching results in a negative bias in the Roost Count trend (see Robustness of Monitoring) and this trend is not therefore considered a reliable measure of population change for this species. We are currently investigating the causes of this negative bias in more detail and exploring ways to correct it (see Developments and Future Directions).

Data from 244 sites contribute to the trend analysis in England (sites surveyed in two or more years).


Return to Soprano pipistrelle population trends; Report home page; Contents page

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