ESR 30:19-28 (2016)  -  DOI: https://doi.org/10.3354/esr00720

Influence of weather on a population of soprano pipistrelle bats in West Wales, UK: a 20 year study estimates population viability

Peter T. Andrews1,†, Robin G. Crump2, David J. Harries3, Margaret M. Andrews4,*

1Oliver Lodge Laboratory, The University of Liverpool, Liverpool L69 3BX, UK
2Orielton Field Centre, Pembroke, Pembrokeshire SA71 5EZ, UK
3Somerton Cottage, Hundleton, Pembrokeshire SA71 5RX, UK
4Liverpool John Moores University, Byrom Street Campus, Liverpool L3 3AF, UK
*Corresponding author: Deceased

ABSTRACT: A nursery roost of the soprano pipstrelle bat Pipistrellus pygmaeus has been monitored continuously between 1 April and 27 September (Weeks 1-26) for 20 yr to promote conservation of the species, which declined over the last century. The long-term study, essential to estimate a reliable population trend, is linked to environmental changes as possible causes of decline. The main emergence was from May to July (Weeks 6-18) when 550 ± 190 (SD) P. pygmaeus were counted. Analysis showed that the year-to-year change in population size of female P. pygmaeusN) and the time of the peak exit count of the females from the roost in May to June could be predicted from the integrated air temperature (degree days, D) between 1 January and 31 March. The regression of ΔN on D showed a statistically significant linear regression line defined by ΔN = 1.31-0.0015 D (R2 = 38.4%; p = 0.005). ΔN = 1.04 to 1.33 reflected a stable to increasing population (Years 1-7 and 15-20). ΔN = 0.78 to 1.00 reflected a stable to decreasing population (Years 8-14). The regression of the time of the first peak exit count, calculated as the number of weeks from 1 April, on D showed a statistically significant linear regression line defined by Weeks = 12.75-0.020 D (R2 = 32.8%; p = 0.008). Rising temperatures between January and March would be detrimental to P. pygmaeus populations.


KEY WORDS: Chiroptera · Degree days · Population · Spring · Temperature · Viability


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Cite this article as: Andrews PT, Crump RG, Harries DJ, Andrews MM (2016) Influence of weather on a population of soprano pipistrelle bats in West Wales, UK: a 20 year study estimates population viability. Endang Species Res 30:19-28. https://doi.org/10.3354/esr00720

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