Abundance and distribution of selected species (SEBI 001) - Assessment DRAFT created Nov 2010

Indicator definition

This indicator shows trends in the abundance of common birds and butterflies over time across their European ranges.

Units

No units have been specified

Policy context and targets

Context description

a. common birds

Composite population trend indicators, such as the common bird index, provide a tangible basis for measuring progress towards the European target of halting biodiversity loss by 2010, and thus towards the global target of reducing the current rate of biodiversity loss by 2010. The strength of this approach is its simplicity, statistical rigor, sensitivity to change, and ease of update (which is possible annually).
The purpose of the common bird index is to enable policy makers to assess and respond to changes in the environment, and then to review the effectiveness of their actions through time. The index complements other trend information on species, sites and habitats. The farmland bird index has been adopted as a structural indicator, as a Sustainable Development Indicator by the EU, and as a baseline indicator under the Rural Development Regulation (Council Regulation (EC) No 1698/2005 on support for rural development by the European Agricultural Fund for Rural Development (EAFRD)), which obliges all EU Member States to monitor farmland birds in the context of agri-environment measures.

b. butterflies

Insects are by far the most species-rich group of animals, representing over 50 % of terrestrial biodiversity. Contrary to most other groups of insects, butterflies are well documented, easy to recognize and popular with the general public. Butterflies use the landscape at a fine scale and react quickly to changes in management, intensification or abandonment. Furthermore, a sustainable butterfly population relies on a network of breeding habitats scattered over the landscape, where species exist in a metapopulation structure. This makes butterflies especially vulnerable to habitat fragmentation. Moreover, many butterflies are highly sensitive to climate change and nitrogen deposition and, because data from fine-scale mapping is available in many countries, they have been used in models predicting the impact of climate change on wildlife. Butterflies have been counted in Butterfly Monitoring Schemes since 1976.

Relation of the indicator to the focal area

a. common birds

Each species reacts differently to the various anthropogenic pressures that potentially
impact on the population size. By monitoring a large enough number of populations
from different birds groups, different biogeographic regions and areas subjected to
different types and levels of pressures, this indicator has a potential to alert decision
makers of the decline of populations in relation to environmental and geographic
factors, as well as their potential drivers.

b. butterflies

The European Butterfly Indicator will be able to deliver a reliable measurement of
changes in the size of European butterfly populations. Since butterfly trends are a good
indicator of changes in the insect group as a whole, which in turn represents more than
50 % of Europe's biodiversity, the European Butterfly Indicator is a useful proxy for a
wider understanding of biodiversity changes.

Targets

No targets have been specified

Related policy documents

No related policy documents have been specified

Methodology

Methodology for indicator calculation

a. common birds

Trend information is derived from annually operated national breeding bird surveys spanning different periods from 18 European countries, obtained through the Pan-European Common Bird Monitoring scheme (PECBM) _⁽¹⁾. A software package named TRIM (Trends and Indices for Monitoring data) (which allows for missing counts in the time series and yields unbiased yearly indices and standard errors using Poisson regression) is used to calculate national species' indices and then to combine these into supranational indices for species, weighted by estimates of national population sizes. Weighting allows for the fact that different countries hold different proportions of each species' European population. Updated population size estimates, derived from BirdLife International (2004) are used for weighting. Although national schemes differ in count methods in the field, these differences do not influence the supranational results because the indices are standardised before being combined. An improved hierarchical imputation procedure was introduced in 2005 to calculate supranational indices. Supranational indices for species were then combined on a geometric scale to create multi-species indicators. For more details see Gregory et al. 2005.

List of species

Common farmland birds, Europe:
Alauda arvensis, Burhinus oedicnemus, Carduelis carduelis, Columba palumbus, Emberiza citrinella, Falco tinnunculus, Galerida cristata, Hirundo rustica, Lanius collurio, Lanius senator, Limosa limosa, Miliaria calandra, Motacilla flava, Passer montanus, Saxicola rubetra, Streptopelia turtur, Sturnus vulgaris, Sylvia communis, Vanellus vanellus.

Common forest birds, Europe:
Anthus trivialis, Bonasa bonasia, Carduelis flammea, Carduelis spinus, Certhia rachydactyla,
Certhia familiaris, Coccothraustes coccothraustes, Dendrocopos minor, Dryocopus martius, Ficedula albicollis, Ficedula hypoleuca, Fringilla montifringilla, Garrulus glandarius, Hippolais icterina, Jynx torquilla, Lullula arborea, Luscinia megarhynchos, Muscicapa striata, Oriolus oriolus, Parus ater, Parus caeruleus, Parus montanus, Parus palustris, Phoenicurus phoenicurus, Phylloscopus collybita, Phylloscopus sibilatrix, Picus canus, Picus viridis, Prunella modularis, Pyrrhula pyrrhula, Regulus regulus, Sitta europaea, Sylvia borin.

Other common birds, Europe:
Accipiter nisus, Aegithalos caudatus, Buteo buteo, Carduelis cannabina, Carduelis chloris, Cettia cetti, Cisticola juncidis, Corvus corone corone/cornix, Corvus monedula, Cuculus canorus, Dendrocopos major, Emberiza schoeniclus, Erithacus rubecula, Fringilla coelebs, Motacilla alba, Parus major, Phylloscopus trochilus, Pica pica, Sylvia atricapilla, Sylvia melanocephala, Troglodytes troglodytes, Turdus merula, Turdus philomelos, Turdus viscivorus, Upupa epops.

Rationale for species selection:

For the indicator as produced in June 2005, the species selection was based on BirdLife's Habitats for birds in Europe (Tucker and Evans 1997) - arguably the most comprehensive treatment of habitats and habitat use by birds. It quantitatively assesses the proportion of each species' population that occurs in predefined habitat types across Europe. The overall assessment, while mostly quantitative, also relied to some degree on expert judgment through habitat working groups.

In the PECBM scheme, species were classified to habitat using the assessment of Tucker and Evans (1997), with the exception that montane grassland, (originally included as a sub-class of agricultural habitats) was classified as a separate habitat. All species with more than 75 % of their population occurring in one of the following eight habitats were classified as specialists of that habitat: marine; coastal; inland wetland; tundra, mires and moorland; boreal and temperate forests; Mediterranean forest, shrubland and rocky habitats; agricultural and grassland (excluding montane grassland); and montane grassland (Tucker and Evans 1997).

In addition, species with 10-75 % of their population using only one of the above were classed as specialists in that habitat, according either to Tucker and Evans (1997) for
Species of European Conservation Concern (SPECs), or according to the description of Snow and Perrins (1998) for non-SPECs. Species with 10-75 % of their population in three or more woodland or farmland sub-categories in Tucker and Evans (1997) and 10 - 75 % of their population in only one other habitat category were classified as woodland or farmland specialist species respectively.

Remaining species with more than 10 % of their population occurring on more than one habitat were classed as non-specialists. Any species that did not meet the above criteria (due to insufficient data) remained unclassified. Tucker and Evans (1997) include a further habitat of lowland Atlantic heathland; however, no species met the criteria to be classed as a specialist of this habitat.

This species-habitat classification is being used in a number of BirdLife analyses - for example, of farmland birds and long-distance migrants using Bird in Europe 2 trends (Donald et al., 2006; Sanderson et al., 2006). The PECBM scheme also explores a biogeographical approach to species selection and habitat choice knowing that some species may have different habitat preferences according to the biogeographic context.

b. butterflies

The field method is based on the British Butterfly Monitoring Scheme (Pollard and Yates, 1993), in use in the United Kingdom since 1976. Counts are made on a line transect of 5 or 10 m wide with homogeneous vegetation and vegetation structure. From March or April to September or October all butterflies 2.5 m to the left and right of the recorder and 5 m in front and above should be counted under standardised weather conditions. The frequency varies from weekly to three or four visits during the season. Most of the sites are recorded by skilled volunteers. All recorders have a good knowledge of the butterfly fauna at their transect, and their results are checked by butterfly experts. Feest (2006) and van Swaay and Feest (in prep.) show that the butterfly survey data can be used to generate biodiversity quality indices for sites such that trends in biodiversity quality can be deduced. This will provide evidence of change more quickly than simple assessments and in a stastically robust way.

The main objective of the monitoring schemes is to assess changes in abundance at national and regional levels of butterflies, including species of the Habitat Directive.

A European index and trend is produced for each species by combining national results for that species. The individual European species indices are combined (averaged) to create multi-species supranational indicators. This method is based on the one for bird indicators (Gregory et al., 2005):

1. At National level: the indices for each species are produced for each country, using TRIM (Pannekoek and Van Strien, 2003). TRIM is a computer programme to analyse time-series of counts with missing observations using Poisson regression.

2. At Supranational level: to generate European trends, the difference in national population size of each species in each country has to be taken into account. This weighting allows for the fact that different countries hold different proportions of a species' European population (Van Strien et al., 2001). A weighting factor is established as the proportion of the country (or region) in the European distribution (Van Swaay and Warren, 1999). The missing year totals are estimated by TRIM in a way equivalent to imputing missing counts for particular sites within countries (Van Strien et al., 2001).

3. At multi-species level: for each year the geometric mean of the supranational indices is calculated.

List of species

Widespread species: Ochlodes sylvanus, Anthocharis cardamines, Lycaena phlaeas, Polyommatus icarus, Lasiommata megera, Coenonympha pamphilus and Maniola jurtina.

Specialist species: Erynnis tages, Thymelicus action, Spialia Sertorius, Cupido minimus, Maculinea arion, Maculinea nausithous, Polyommatus bellargus, Polyommatus semiargus, Polyommatus coridon and Euphydryas aurinia.

^{_{(1) The PECBM scheme is a partnership involving the European Bird Census Council, the Royal Society for the Protection of Birds, BirdLife International and Statistics Netherlands that aims to deliver policy relevant biodiversity indicators for Europe.}}

Methodology for gap filling

No methodology for gap filling has been specified. Probably this info has been added together with indicator calculation.

Methodology references

• a. common birds BirdLife International (2004). Birds in Europe: population estimates, trends and conservation status. Cambridge, United Kingdom: BirdLife International (BirdLife Conservation Series No. 12). Donald, P. F., Sanderson, F. J., Burfield, I. J., van Bommel, F. P. J. (2006). Further evidence of continent-wide impacts of agricultural intensification on European farmland birds, 1990-2000. Agriculture, Ecosystems and Environment 116 (2006) 189-196. Gregory, R. D., van Strien, A., Vorisek, P., Meyling, A. W. G., Noble, D. G., Foppen, R. P. B. and Gibbons, D. W. (2005) Developing indicators for European birds. Phil.Trans. R. Soc. B. 360, 269-288. Sanderson, F. J., Donald, P. F., Paina, D. J., Burfield, I. J., van Bommel, F. P. J. (2006). Long-term population declines in Afro-Palearctic migrant birds. Biological Conservation 131 (2006) 93-105. Snow, D. W., Perrins, C. M., (1998). The Birds of the Western Palearctic: Concise Edition. Oxford University Press, Oxford, United Kingdom. Strategy for the Wider Environment. BirdLife International, Cambridge, United Kingdom. Tucker, G. M., Evans, M. I., (1997). Habitats for Birds in Europe: A Conservation.
• b. butterflies Donald, P. F.; Sanderson, F. J.; Burfield, I. J.; Bierman, S. M.; Gregory, R. D.; and Waliczky, Z., 2007. 'International Conservation Policy Delivers Benefits for Birds in Europe'. Science 317: 810 Feest, A. (2006) Establishing baseline indices for the environmental quality of the biodiversity of restored habitats using a standardised sampling process. Restoration Ecology, 14:112-122. Gregory, R. D., Van Strien, A. J., Vorisek, P., Gmelig Meyling, A. W., Noble, D. G., Foppen, R. P. B. and Gibbons, D. W. (2005) Developing indicators for European birds. Phil. Trans. R. Soc. B. 360, 269-288. Pannekoek, J. and Van Strien, A. J. (2003) TRIM 3 manual. Trends and Indices for Monitoring data. CBS, Statistics Netherlands, Voorburg, Netherlands. Pollard, E. and Yates, T. J. (1995) Monitoring butterflies for ecology and conservation. Chapman and Hall, Londen. Thomas, J. A., Telfer, M. G., Roy, D. B., Preston, C. D., Greenwood, J. J. D., Asher, J., Fox, R., Clarke, R. T. and Lawton, J. H. (2004) Comparitive losses of British Butterflies, Birds, and Plants and the Global Extinction Crisis. Science 303, 1879-1881. Thomas, J. A. (2005) Monitoring change in the abundance and distribution of insects using butterflies and other indicator groups. Phil. Trans. Soc. B. 360, 339-357. Van Strien, A. J., Pannekoek, J. and Gibbons, D. W. (2001) Indexing European bird population trends using results of national monitoring schemes: a trial of a new method. Bird Study 48, 200-213. Van Swaay, C. A. M. and Warren, M. S. (1999) Red Data Book of European Butterflies (Rhopalocera). Nature and Environment series, No. 99, Council of Europe, Strasbourg. Van Swaay, C. A. M., Nowicki, P., Settele, J., van Strien, A.J. (2008) Butterfly monitoring in Europe: methods, applications and perspectives, Biodivers Conserv DOI 10.1007/s10531-008-9491-4 Van Swaay, C. A. M., van Strien, A.J. (2005) Using butterfly monitoring data to develop a European grassland butterfly indicator. In Proceeding Studies on the ecology and conservation of Butterfliesin Europe, december 2005
• The European Butterfly Indicator for Grassland species: 1990-2007 Van Swaay, C.A.M. & Van Strien, A.J. (2008) The European Butterfly Indicator for Grassland species 1990-2007. Report VS2008.022, De Vlinderstichting, Wageningen

Uncertainties

Methodology uncertainty

No uncertainty has been specified

Data sets uncertainty

No uncertainty has been specified

Rationale uncertainty

MAIN DISADVANTAGES OF THE INDICATOR

a. common birds

• Temporal coverage: until the early 1990s, rather few European countries had common bird monitoring schemes in place, which restricts how far back in time representative trends can be calculated.
• Spatial coverage: coverage of western and central Europe is now almost complete, but a few gaps remain, and a further expansion eastwards is desired; efforts to fill them are underway.

b. butterflies

• Limited geographical coverage.

ANALYSIS OF OPTIONS

As another candidate indicator for the headline indicator, the living planet index (LPI) was considered. The weakness of the LPI is that it relies on data that are biased towards well-monitored vertebrates in temperate latitudes, including many species that have been/are subject to ongoing conservation action, and thus is not representative of biodiversity as a whole. It relies on a limited amount of reliable time-series data gathered from a variety of sources published in scientific journals, NGO literature, or on the worldwide web. Work is ongoing to strenghten the LPI.

The PECBM indicator work is based on generic sampling of species, with no a priori bias on their selection. It has been presented and well-received at international conferences and meetings.

Options for other biodiversity species-based indicators are being considered.