The birds are speaking to Europe

While climate change may harm nearly three quarters of European birds, a few southern species, such as the European bee-eater (Merops apiaster) and the hoopoe (Upupa epops), on the other hand, may extend their territory northwards.  © S.Spasov /
While climate change may harm nearly three quarters of European birds, a few southern species, such as the European bee-eater (Merops apiaster) and the hoopoe (Upupa epops), on the other hand, may extend their territory northwards.
© S.Spasov /

New bio-indicators, based on common bird populations in Europe, can be used to assess the biological consequences of human activities: the use of fossil fuels and changes in land use.

‘Climate change is already having a measurable impact on birds in Europe,’ a group of scientists declared in an article describing the first bio-indicator of the impact of climate change on nature in Europe(1). Evidence of this impact on biodiversity has accumulated in recent years: changes in the levels of profusion and distribution of plant and animal species, time-lags of certain events, such as flowering and reproduction, changes to migration patterns… Until very recently, however, there was no indicator with which to demonstrate this at the European level. In order to create this climate impact indicator (CII), researchers combined data from 1980 to 2005 on the diffusion of 122 common bird species across 20 European countries. This data is drawn from the Pan- European Common Bird Monitoring Scheme (PECBMS) project(2) and includes models which predict how each of these species may respond to climate change.

A declining trend in the CII can be observed during the 1980s, probably reflecting the influence of cold winters and changes in land use, which prompted a decline in bird populations. Since the end of the 1980s, however, the indicator has not stopped rising, showing that the impact of global warming has surpassed those of other pressures, whether environmental or not. Some bird species have seen their populations increase, while others have witnessed a decline: the problem is that 75 % of the species studied fall into the second category (92 of the 122 surveyed during the study).

The most significant threat relates to greenhouse gas emissions, which have increased significantly since the Industrial Revolution: the use of fossil fuels and deforestation generate carbon dioxide (CO2) emissions, which combine with other major greenhouse gases: water vapour (H2O), methane (CH4) and nitrous oxide (N2O).

Other measures taken by the PECBMS

The main goal of the PECBMS is to promote the use of birds as bio-indicators of nature’s general state of health, by using scientific data gleaned from large-scale monitoring schemes.

Besides the CII, the PECBMS has helped design biodiversity indicators based on common European birds in two habitats: farm land and forests. While overall population levels fell by 10 % between 1980 and 2006(3), those of common forest birds declined by 9 %, and those of common farmland birds fell by 48 % during the same period. It is becoming increasingly apparent that this decline was provoked by intensive farming practices and sylviculture, which elicited a decline in crop and plant diversity, the destruction of meadows and borders, an increase in the use of pesticides and fertilisers, and drainage – all of which indirectly affects the birds via the food chain. As well as designing these indicators, the PECBMS also published a best practice guide to monitor the birds, which is available on the European Bird Census Council (EBCC) website.

In April 2009, the PECBMS received confirmation of renewed project funding for an additional three years from the Directorate-General for the Environment of the European Commission, and also continues to enjoy financial support from the Royal Society for the Protection of Birds (RSPB). Data updates are scheduled to take place on an annual basis in order to ensure that the data quality continues to improve, and that the geographic reach of the programme extends, along with the number of bird species studied. Attempts will also be made to produce indicators for other habitats, such as marshes and habitats subject to agri-environmental policies.

From science to policy

Such findings indicate that the changes observed in nature and their impact on the birds and on ourselves must be taken seriously. At the World Summit on Sustainable Development in 2002, one of the decisions taken was to reduce the current loss of biodiversity by 2010.

If Europe wants to achieve this ambitious goal of halting the decline of biodiversity loss, it must intensify its efforts to implement nature conservation measures. The European Union and the European Environment Agency have adopted the CII and the Farmland Bird Indicator (an indicator based on farmland birds) as official measuring tools with which to assess biodiversity trends. In April 2009, the Commission also published a white paper, which set out the framework for adaptation measures, in order to reduce the European Union’s vulnerability to the impact of climate change(4).

Isabelle Noirot

  1. Gregory et al., 2009,
  2. The PECBMS is a partnership which was established in 2002 by ornithologists and nature conservation specialists who cooperated via other organisations: BirdLife International, the European Bird Census Council (EBCC) and the Royal Society for the Protection of Birds (RSPB), with technical assistance from Statistics Netherlands. The PECBMS compiles population data collated from annual monitoring schemes carried out in Europe. It is financed by the European Commission and the RSPB.

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The concept of the indicator species

An indicator serves as a substitute for a parameter that is too short-lived or too difficult to measure directly. In economics, the Dow Jones is a stock market indicator that represents trends rather than total market analysis. In biology, indicators can be used to measure specific factors, such as air quality via lichens, ground moisture via the plant species present, or even contamination from pesticides, as reflected by populations of birds of prey and, more recently, bees.

The Earth Summit, held in Rio in 1992, prompted the development of a similar indicator in the field of biodiversity. The PECBMS chose indicators based on birds for reasons that are both practical and scientific: birds are relatively easy to observe and are plentiful, their biology and behaviour have been extensively studied and they respond rapidly to change. These indicators use tens of common bird species to generate a comprehensive picture of the environment.

A vision of the future

Do the trends observed among birds foreshadow similar trends among other species? This is an important question which still awaits a clear answer. Scientists are suggesting, however, that increased global warming could alter the way in which the entire ecosystem operates and that human activities (environmental changes and the spread of exotic species) will result in a decrease in the number of specialist species and a small increase in the number of generalist and harmful species, which thrive in a disrupted environment. The result: an environment with impaired biodiversity, at all levels. This is known as biotic homogenisation.


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