Dramatic decline of northern bat Eptesicus nilssonii in Sweden over 30 years
(2020) In Royal Society Open Science 7(2).- Abstract
We monitored northern bat Eptesicus nilssonii (Keyserling & Blasius, 1839) acoustically along a 27 km road transect at weekly intervals in 1988, 1989 and 1990, and again in 2016 and 2017. The methodology of data collection and the transect were the same throughout, except that the insect-attracting mercury-vapour street-lights along parts of the road were replaced by sodium lights between the two survey periods. Counts along sections of the transect with and without streetlights were analysed separately. The frequency of bat encounters in unlit sections showed an average decline of 3.0% per year, corresponding to a reduction of 59% between 1988 and 2017. Sections with street-lights showed an 85% decline over the same period (6.3%... (More)
We monitored northern bat Eptesicus nilssonii (Keyserling & Blasius, 1839) acoustically along a 27 km road transect at weekly intervals in 1988, 1989 and 1990, and again in 2016 and 2017. The methodology of data collection and the transect were the same throughout, except that the insect-attracting mercury-vapour street-lights along parts of the road were replaced by sodium lights between the two survey periods. Counts along sections of the transect with and without streetlights were analysed separately. The frequency of bat encounters in unlit sections showed an average decline of 3.0% per year, corresponding to a reduction of 59% between 1988 and 2017. Sections with street-lights showed an 85% decline over the same period (6.3% per year). The decline represents a real reduction in the abundance of bats rather than an artefact of changed distribution of bats away from roads. Our study conforms with another long-term survey of the same species on the Baltic island of Gotland. Our results agree with predictions based on climate change models. They also indicate that the decline was caused directly by the disuse of the insect-attracting mercury-vapour street-lights, which may have resulted in lower availability of preferred prey (moths). In the 1980s, E. nilssonii was considered the most common bat in Sweden, but the subsequent decline would rather qualify it for vulnerable or endangered status in the national Red List of Threatened Species.
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- author
- Rydell, Jens LU ; Elfström, Marcus ; Eklöf, Johan and Sánchez-Navarro, Sonia
- organization
- publishing date
- 2020-02-05
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Climate change, Lepidoptera, Light pollution, Line transects, Long-term monitoring, Population decline
- in
- Royal Society Open Science
- volume
- 7
- issue
- 2
- article number
- 191754
- publisher
- Royal Society Publishing
- external identifiers
-
- pmid:32257332
- scopus:85081589739
- ISSN
- 2054-5703
- DOI
- 10.1098/rsos.191754
- language
- English
- LU publication?
- yes
- id
- c0b675cb-4a35-4dea-92da-0de6ad119213
- date added to LUP
- 2020-04-07 14:56:06
- date last changed
- 2024-10-03 00:26:01
@article{c0b675cb-4a35-4dea-92da-0de6ad119213,
abstract = {{<p>We monitored northern bat Eptesicus nilssonii (Keyserling & Blasius, 1839) acoustically along a 27 km road transect at weekly intervals in 1988, 1989 and 1990, and again in 2016 and 2017. The methodology of data collection and the transect were the same throughout, except that the insect-attracting mercury-vapour street-lights along parts of the road were replaced by sodium lights between the two survey periods. Counts along sections of the transect with and without streetlights were analysed separately. The frequency of bat encounters in unlit sections showed an average decline of 3.0% per year, corresponding to a reduction of 59% between 1988 and 2017. Sections with street-lights showed an 85% decline over the same period (6.3% per year). The decline represents a real reduction in the abundance of bats rather than an artefact of changed distribution of bats away from roads. Our study conforms with another long-term survey of the same species on the Baltic island of Gotland. Our results agree with predictions based on climate change models. They also indicate that the decline was caused directly by the disuse of the insect-attracting mercury-vapour street-lights, which may have resulted in lower availability of preferred prey (moths). In the 1980s, E. nilssonii was considered the most common bat in Sweden, but the subsequent decline would rather qualify it for vulnerable or endangered status in the national Red List of Threatened Species.</p>}},
author = {{Rydell, Jens and Elfström, Marcus and Eklöf, Johan and Sánchez-Navarro, Sonia}},
issn = {{2054-5703}},
keywords = {{Climate change; Lepidoptera; Light pollution; Line transects; Long-term monitoring; Population decline}},
language = {{eng}},
month = {{02}},
number = {{2}},
publisher = {{Royal Society Publishing}},
series = {{Royal Society Open Science}},
title = {{Dramatic decline of northern bat Eptesicus nilssonii in Sweden over 30 years}},
url = {{http://dx.doi.org/10.1098/rsos.191754}},
doi = {{10.1098/rsos.191754}},
volume = {{7}},
year = {{2020}},
}