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Serotine trends for Great Britain

Eptesicus serotinus

Species factsheetDistribution and abundance

GB-level population trends for serotine from the Field Survey and the Roost Count are shown on this page.

Population trends are also produced for serotine in England. Serotine is only rarely recorded in Wales, therefore there are insufficient data to calculate a population trend for that country. This species does not occur in Scotland.


Field Survey

GB index of serotine population from Field Surveys

Serotine Field Survey GB 2015

 

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 2015 is shown as a dashed line to indicate that it is provisional.

The smoothed index is currently 9.5% below the 1999 base year value, equivalent to an annual decrease of 0.6%. The trend increased from the start of the monitoring period to 2012, after which there has been a decline. This decline has continued in 2015, however overall there has been no significant change in the smoothed index since the baseline year. Further years of data are needed to show whether this decline will be sustained and become significant.

Data from 450 sites surveyed between 1998 and 2015 contribute to the overall trend analysis.

Note: As serotine is restricted to southern parts of GB no geographic weighting has been applied to this analysis.

 


Roost Count 

GB index of serotine population from Roost Counts

Serotine Roost Count GB 2015

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 2015 is shown as a dashed line to indicate that it is provisional.

The smoothed index is currently 22.1% below the 1999 value, equivalent to an annual decrease of 1.6%. There has been no significant change in the smoothed index since the baseline year.

Data from 102 sites contribute to the trend analysis from 1997-2015 (sites surveyed in two or more years).

 


Summary of survey results

Trends from both the Field Survey and Roost Count show no sigificant change in the smoothed population index since the baseline year. The population of serotine in Great Britain is considered to be have been stable over the period 1999-2015. However this finding should be treated with caution as this species is encountered relatively infrequently during surveys. Sample sizes are therefore relatively small and the level of uncertainty associated with these trends large, meaning trends for this species may be difficult to detect.

 


Distribution and abundance

Serotine is an uncommon species, with a distribution mostly limited to areas south of a line drawn from the Wash across to south Wales. More recently, records have also been found in North Wales.

Population estimate 

The population estimates are considered to be poor and should be treated with caution. Estimates are based on very limited population data and rely on expert opinion only

Country UK England Wales Scotland N.Ireland
Number 15,000  15,000 unknown does not occur does not occur
 Source  Harris et al. 1995 Harris et al. 1995       

 


References

Harris S., Morris, P., Wray, S. & Yalden, D. (1995) A review of British mammals: population estimates and conservation status of British mammals other than cetaceans. JNCC, Peterborough.


Return to:

Top of pageSpecies population trendsReport HomeContents page

 

 

Serotine factsheet

 

Listen to how serotine sounds on a bat detector 

 

 

Current distribution of serotine in the UK

(Map taken from 3rd Report under Article 17 on implementation of the Habitats Directive in the UK, JNCC 2013)

Serotine distribution

 

 

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