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Soprano pipistrelle trends for Scotland

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

Population trends for soprano pipistrelle are also produced for Great Britain and England.

 


Field Survey

Scotland index of soprano pipistrelle population from Field Surveys

Soprano pipistrelle Field Survey trend Scotland

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 54.1% above the 1999 base year value, equivalent to an annual increase of 2.6%. The smoothed index increased steadily from 1999 to a peak in 2007, and was significantly higher than the baseline year between 2005 and 2012. Since 2008 the smoothed index has been gradually declining so that currently the smoothed index does not differ significantly from the 1999 baseline. However the number of sites monitored by the Field Survey in Scotland is small and the level of uncertainty associated with the smoothed index is high, meaning trends for common pipistrelle in Scotland may be difficult to detect using data from the Field Survey.

Data from 76 sites contribute to the trend analysis in Scotland.


Roost Count 

Scotland index of soprano pipistrelle population from Roost Counts

Soprano pipistrelle bat roost trend Scotland

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 50.0% below the 1999 base year value, equivalent to an annual decrease of 4.0%. 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 83 sites contribute to the trend analysis in Scotland (sites surveyed in two or more years).

 


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

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