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Brown long-eared bat trends for Great Britain

Plecotus auritus

Species factsheetDistribution and abundance

GB-level populations trends for brown long-eared bat from the Hibernation Survey and the Roost Count are shown on this page.

Population trends for brown long-eared bat are also produced at country-level for England and Wales. There are insufficient data available to calculate a population trend for this species in Scotland.


Hibernation Survey

GB index of brown long-eared bat population from Hibernation Surveys

Brown long-eared bat Hibernation Survey GB 2015Note: 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 7.3% below the 1999 base year value, equivalent to an annual decrease of 0.5%. There has been no significant change in the smoothed index since the baseline year.

From all years for which data are available (1990-2015), counts from 444 sites contribute to the trend (sites surveyed in two or more years with brown long-eared bat recorded in at least one year).


Roost Count 

GB index of brown long-eared bat population from Roost Counts

Brown long-eared bat 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 28.2% above the base year value, equivalent to an annual increase of 1.8%. The trend has fluctuated since montioring started, and is currently increasing, however the confidence intervals of the trend have always overlapped the index value of the base year. There has been no significant change in the smoothed index since the baseline year.

Data from 157 sites surveyed between 1990 and 2015 contribute to the trend (sites surveyed in at least two years).

Note: the baseline year for calculation of this trend has been set at 2001 as very few roosts were counted in earlier years.


Summary of survey results

Trends from both the Hibernation Survey and the Roost Count show no significant change in the smoothed index since the baseline year. The population of brown long-eared bat in Great Britain is considered to have been stable over the period 1999-2015.

 


Distribution and abundance

The brown long-eared bat is found throughout the UK with the exception of exposed islands with little woodland such as Orkney, Shetland and the Outer Herbrides. 

Population estimate

The population estimates are considered to be poor and should be treated with caution. Estimates are based on limited population data and are extrapolated from surveys of only part of the population

Country

UK

England

Wales

Scotland

N.Ireland

Number

245,000

155,000

17,500

27,500

45,000

 Source

 

 Harris et al. 1995

 Harris et al. 1995

 Harris et al. 1995

Russ 1999 


 

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.

Russ, J.M. 1999. The Microchiroptera of Northern Ireland: community composition, habitat associations and ultrasound. Unpublished PhD thesis. Queen’s University, Belfast.


Return to:

Top of pageSpecies population trendsReport HomeContents page

 

 

Brown long-eared bat factsheet

 

Listen to how a brown long-eared bat sounds on a bat detector 

 

 

Current distribution of brown long-eared bat in the UK

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

Brown long-eared bat distribution

 

 

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