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Indicator Facts

CBD Strategic Goal: B. Reduce the direct pressures on biodiversity and promote sustainable use.

C. To improve the status of biodiversity by safeguarding ecosystems, species and genetic diversity.

Main Aichi Biodiversity Target: Target 12. By 2020 the extinction of known threatened species has been prevented and thier conservation status, particularly of those most in decline, has been improved and sustained.

Secondary Aichi Biodiversity Targets: 5, 7

CBD AHTEG proposed Headline Indicators: Trends in abundance, distribution and extinction risk of species; Trends in pressures from unsustainable agriculture, forestry, fisheries and aquaculture; Trends in pressures from habitat conversion, pollution, invasive species, climate change, overexploitation and underlying drivers

Key Indicator Partners:      


Regional and National Associate Indicator Partners:

●European Bird Census Council ●National Audubon ●NABCI State of the Birds Subcommittee ●USGS Patuxent Wildlife Research Centre ●Environment Canada Canadian Wildlife Service ●Birds Australia ●Museum National d'Histoire Naturelle ●Czech Society for Ornithology ●Statistics Netherlands ● SOVON ●British Trust for Ornithology ●Lund University ●Dansk Ornitologisk Forening ●BirdWatch Ireland ●BirdLife Austria ●Directorate of Nature Management Norway ●Norwegian Institute of Nature Research ●BirdLife Norway ● Nord-Trøndelag University College ●Swiss Ornithological Institute ●Catalan Ornithological Institute ●Centro Italiano Studi Ornitologici ●LIPU ● FaunaViva ●Aves-Natagora ●Zoological Museum of the Finnish Museum of Natural History ●Finnish Game of Fisheries Research Institute ●Finnish Environmental Institute ●SPEA ●Latvian Ornithological Society and Latvian Fund for Nature ●BirdLife Botswana ●Nature Kenya ●Nature Uganda

Type of Indicator: Pressure

Other conventions or processes using the indicator: Wild Bird indices are used in a range of national, European and EU environmental reporting processes, as well as by OECD and the Convention on Biological Diversity for e.g. in National Reports and in Global Biodiversity Outlook.

Development Status: Ready for national use


Background: There is growing recognition that the inexorable decline of nature may have profound consequences for the lives of people and their economies through the loss of natural resources and the ecological services they provide. Birds can act as excellent sentinels, barometers or indicators of trends in the state of nature and of the sustainability of human land use and environmental health. Birds occur in all habitats, can reflect trends in other animals and plants, and can be sensitive to environmental change. A great deal of high quality data exists on birds and new data are relatively inexpensive to collect.

Policy questions that the indicator addresses: Birds are recognised as good indicators of environmental change and as useful proxies of wider changes in nature. The Wild Bird Index measures average population trends of a suite of representative wild birds as an indicator of the general health of the environment.

Indicator relationship to main Aichi Biodiversity Target (12): The WBI measures average population trends of a suite of representative wild birds, as an indicator of the general health of the wider environment. The WBI is an easy-to-understand indicator that can be calculated for different geographic areas and habitats. This means that different WBIs can be produced for areas such as farmland and woodland, or inside and outside protected areas if suitable data is available. It is useful for analysis, interpretation of environmental issues and communication.

WBIs deliver scientifically robust and representative indicators for birds to support formal measurement and interpretation of national, regional and global targets to reduce, or halt, the rate of biodiversity loss.  WBIs measure extinction and colonisation processes at a local scale among widespread and familiar birds in the environment (the survey methods count all bird species detected). In doing so, they shed light on the sustainability of the human use of that environment and how human impact is changing.  By grouping species tied to particular habitats, it is possible to create habitat-based indices, hence providing an insight into the health of those habitats and an indication of the sustainability of human use.


Data Information

Data Available: Regional/national time series for the North American indices began 1968, while the European indices began 1980

Indicator can be disaggregated at: Regional and national levels


The Global Wild Bird Index (WBI) aims to measure population trends of a representative suite of wild birds, to act as a barometer of the general health of the environment and how it is changing. The methodology for producing WBIs is well developed; European WBIs have already been produced and are being used to measure progress towards the headline target of the new EU Biodiversity Strategy to 2020 - Halting the loss of biodiversity and the degradation of ecosystem services in the EU by 2020, and restoring them in so far as feasible, while stepping up the EU contribution to averting global biodiversity loss. They are used by nearly twenty national governments in Europe within strategies to assess sustainability and environmental health. WBIs have recently been published for North America, and WBI initiatives have begun in Africa (particularly in Botswana, Kenya and Uganda) and Australia. The WBI measures biodiversity change in a similar fashion to the Living Planet Index, the main difference is that the WBI only incorporates trend data from formally designed breeding bird surveys to deliver scientifically robust and representative indicators. The requirement for robust data, however, means that data coverage is currently patchy and the WBI is not presently applicable at a global scale.

The WBI project aims to promote and encourage the development of WBIs from national population monitoring schemes. Where such schemes already exist, it will coordinate and facilitate the collation of bird species’ data and the generation of indices and indicators. Where there are none, it will provide tools and support to implement similar data collation and synthesis in a representative set of countries across regions, with the funds available to the project.   

Future development is however, funding dependent.


Contributing data are generated at the local level so WBIs are scalable and can be aggregated or disaggregated at the global, regional and national (sub- national) level. WBIs can also be disaggregated by the habitat or guild a bird occurs in, or by aspects of species’ ecology, in order to aid interpretation. WBIs are particularly suited to tracking trends in the condition of habitats.

Level at which the indicator is currently used: Sub-global

Levels at which the indicator could be used in the future: Global, regional, national, sub-national/local

The Indicator


Wild Bird Index for habitat specialist birds in North America (1968-2012) and Europe (1980-2012)

Source: North American Breeding Bird Survey and European Bird Census Council/RSPB/BirdLife International/Statistics Netherlands


How to Interpret the Indicator

The WBI is the average population trend in a group of bird species, often grouped by their association and dependence on a particular habitat. They are particularly suited to tracking trends in the condition of habitats through obligate or specialist species. A decrease in the WBI means that the balance of species’ population trends is negative, representing biodiversity loss. If the index is constant, there is no overall change. An increase in the WBI means that the balance of species’ trends is positive, implying that biodiversity loss has halted. However, an increasing WBI may, or may not, always equate to an improving situation in the environment. It could in extreme cases be the result of expansion of some species at the cost of others, or reflect habitat degradation. In all cases, detailed analysis must be conducted to interpret the indicator trends. The composite trend can of course hide important trend patterns for individual species, but it is nonetheless the best description of the overall trend in that species group.

Current Storyline

Long-term bird population indices are currently only available from North America (from 1968) and Europe (from 1980), but a wild bird index combining these data shows that specialist birds have declined by more than 20% since 1980.  The largest population declines have occurred in grasslands and arid lands in North America and in farmed lands in Europe, whereas widespread specialists of forests show fluctuating but stable trends in both North America and Europe. There is the suggestion that North American forest and grassland specialists and European forest specialists have been recovering in recent years, but we do not know if that trend will continue. The Global Wild Bird Index project seeks to mobilise relevant information on bird trends globally and to encourage the establishment of breeding bird surveys in countries and regions where none exist.  For example, national schemes have been successfully established in several African countries recently.

National Use

The Global WBI, which will be built on national data, is still in development. However, nations and regions have produced their own WBIs already from national bird monitoring schemes (e.g. Europe and North America) and these data will feed in to the global indicator.  Trend analysis and WBIs will soon be available from several African countries too.

WBIs are being used at a national level in at least 26 European countries, including Austria, Belgium (Wallonia), Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italia, Latvia, Luxembourg, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland, and UK.

New bird monitoring schemes are being initiated in a number of countries in Europe, with the Africa region piloting this approach, but others elsewhere. These will produce data to allow national indicators to be produced, and to contribute to a global WBI in due course.

For more information about producing regional and national Wild Bird Indices, contact Richard Gregory from RSPB and/or Ian Burfield from BirdLife International.

Future Development

There is a huge amount of ongoing and historic bird monitoring information (bird surveys and atlases) available across the globe; the challenge is to collate such data and to assess the degree to which it might contribute meaningfully to a global WBI. Information on such bird monitoring programmes and initiatives is being gathered from across the globe by the WBI project. The Wild Bird Index for habitat specialists will continue to expand, hopefully into a truly global indicator, and will soon include data from several African countries, including Uganda and Botswana, and from China. The latest data used in this storyline is from 2012; the next data update is due in 2015. New bird-monitoring schemes are now ongoing in countries such as Botswana, Kenya, Uganda and China.  Assistance and encouragement is being provided to other countries.  RSPB/BirdLife hopes to take this work forwards with indicator partners and other experts. Future development is funding dependent.

Indicator Publications
The State of the Birds 2014. United States of America report.English
Analysis of the North American Breeding Bird Survey Using Hierarchical Models (2011)Journal Article: Sauer, J.R & Link, W.A. Auk 128(1), 87-98.
State of the World's Birds: Indicators for our changing world (2013)English, PDF.
State of Africa's Brids (2013)English, PDF.
The state of the Birds 2013 - United States of America ReportEnglish, PDF.
Essential Biodiversity Variables (2013)Journal Article: Multiple Authors. Science 339, 277-278.
Desirable mathematical properties of indicators for biodiversity change (2012)Journal Article: Multiple Authors. Ecological Indicators 14, 202-208.
Trends in abundance and biomass of widespread European farmland birds: how much have we lost? (BOU Proceedings 2010)English
Wild Bird Indicators: Using Composite Population Trends of Birds as Measures of Environmental Health (2010)Journal Article: Multiple Authors. Ornithological Science 9(1), 3-22.
Global Biodiversity: Indicators of Recent Declines (2010)Journal Article: Multiple Authors. Science 328, 1164-1168.
The Wild bird Index - Guidance for National and Regional Use (UNEP-WCMC 2010)English
Quantifying the impact of land-use change to European farmland bird populations (2010)Journal Article: Multiple Authors. Agriculture, Ecosystems and Environment 137, 3-4, 348-357.
Wild birds as indicators in europe: latest results from the Pan-european Common Bird Monitoring Scheme (2009)Journal Article: Multiple Authors. Avocetta 33, 1-6.
State of the Birds 2009: United States of America (U.S. NABCI Committee 2009)English
An indicator of the impact of climatic change on European bird populations (2009)Journal Article: Multiple authors. PLoS ONE 4(3): e4678.
Best Practice Guide for Wild Bird Monitoring Schemes (CSO/RSPB 2008)English
State of the World’s Birds. Indicators for our changing world (BirdLife International 2008)English
El estado de conservación de las aves del mundo. Indicadores en tiempos de cambio (BirdLife International 2008)Español
Etat des populations d’oiseaux dans le monde. Des indicatuers pour un monde qui change (BirdLife International 2008) Français
The Global Wild Bird Indicator Project (RSPB & BirdLife International 2008)Information Leaflet
Population trends of 48 common terrestrial bird species in Europe: results from the Pan-European Common Bird Monitoring scheme (2008)Journal Article: Multiple authors. Revista Catalana d'Ornitologia 24. 4-14.
The generation and use of bird population indicators in Europe (2008)Journal Article: Multiple authors. Bird Conservation International 18, S223-S244.
Population trends of widespread woodland birds in Europe (2007)Journal Article: Multiple authors. Ibis, 149, (S2), 78-97.
Birds as biodiversity indicators for Europe (2006)Journal Article: Gregory, R.D. Significance 3, 106-110.
Developing indicators for European birds (2005)Journal Article: Multiple authors. Phiosophical Transactions of the Royal Society B. 360, 269-288.
The state of play of farmland birds: population trends and conservation status of farmland birds in the United Kingdom (2004)Journal Article: Multiple authors. Ibis 146 (Suppl. 2), 1-13.
Using birds as indicators of biodiversity (2003)Journal Article: Multiple authors. Ornis Hungarica 12-13, 11-24.
Regional and national indicator links


North America:














Photo credits:
Birds in hanging cages ©stephen boisvert; Peacock ©Chris Chidsey; flock of sanderlings ©Aypho

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