Reduced-effort schemes for monitoring butterfly populations

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Roy, D. B.; Rothery, P.; Brereton, T.. 2007 Reduced-effort schemes for monitoring butterfly populations. Journal of Applied Ecology, 44 (5). 993-1000. 10.1111/j.1365-2664.2007.01340.x

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Official URL: http://www.blackwell-synergy.com/doi/abs/10.1111/j...

Abstract/Summary

1. Butterflies are one of the few insect groups that can be monitored effectively and have the potential to develop national and Europe-wide trends in abundance. 2. For 20 widespread butterfly species, we assess the relative efficiency of reduced-effort schemes compared to the existing design and estimate the number of sites required to detect changes of given magnitudes over specified periods of time. 3. A scheme restricted to three counts during July and August requires twice as many monitored sites on average to achieve comparable precision to the existing 26-week scheme in the United Kingdom. Such a scheme requires 430 monitoring sites on average to achieve 80% power (5% significance level) for detecting a 25% decline in abundance over 10 years. 4. Such a reduced-effort scheme may also mean that volunteers are more willing to record in areas where they are likely to see only a few individuals of a few common species (such as on intensively farmed areas). This could potentially help to ensure that butterfly monitoring schemes achieve a more even geographical coverage and less of a bias towards areas rich in butterflies. 5. Synthesis and applications. Schemes with few sampling visits per year are cost-effective for expanding butterfly monitoring across Europe, and can be applied to national monitoring programmes and lead to effective assessment of continent-wide trends in populations.

Item Type:	Article
Identification Number/DOI:	10.1111/j.1365-2664.2007.01340.x
Programmes:	CEH Programmes pre-2009 publications > Biodiversity
CEH Sections:	Pywell
ISSN:	0021-8901
Additional Keywords:	biodiversity, indicators, Lepidoptera, log-linear model, statistical power, UK butterfly monitoring scheme, wider countryside
NORA Subject Terms:	Zoology Ecology and Environment
Date made live:	30 Jan 2008 16:41
URI:	http://nora.nerc.ac.uk/id/eprint/2250

Item Type:

Article

Identification Number/DOI:

10.1111/j.1365-2664.2007.01340.x

Programmes:

CEH Programmes pre-2009 publications > Biodiversity

CEH Sections:

Pywell

ISSN:

0021-8901

Additional Keywords:

biodiversity, indicators, Lepidoptera, log-linear model, statistical power, UK butterfly monitoring scheme, wider countryside