The Farmland Bird Indicator (FBI) has declined by approximately 30 percent since 2000. Changes in agricultural practices and land use (urbanisation) have reduced the number of farmland birds in the Netherlands. Although downward trends in farmland bird populations are found across the entire European Union, the trend in the Netherlands is one of the most negative. The Dutch FBI is the national version of the EU Farmland Bird Indicator.
The decline in farmland birds in the Netherlands is mainly caused by increasingly intensive farming methods, changes in crop choices and larger scale agricultural programmes. As a result of these developments, many landscape elements like hedge rows and small areas of unused land that served as refuge have disappeared. Added to this,
urbanisation, infrastructural projects and increased traffic are also reducing breeding areas. Measures in recent years like natural management of field edges and agricultural areas and active nest protection, have not been enough to halt the decline.
Of the 27 selected representative farmland species, 21 show a significant decline. The most substantial population decreases are for the Grey partridge, the European turtle dove, the Eurasian tree sparrow and the Black-tailed godwit. The negative trend set in decades ago: a historical reconstruction of farmland bird populations even shows an average decline by more than 50 percent since 1960.
The monitoring data for farmland bird species in the Netherlands are derived from the national monitoring network for breeding birds, which is part of the Ecological Monitoring Network. Annual indices of population numbers per species are determined by Poisson regression (software TRIM, van Strien et al., 2004). To calculate the FBI, the annual indices of population numbers are geometrically averaged over all 27 species concerned (index 2000 = 100). A smoothing algorithm is applied to determine flexible trends.
Developments in the Netherlands in farmland bird numbers are largely the same as those across the European Union, although the decreasing trend in the EU is more gradual, with an average decline of 17 percent since 2000 (www.ebcc.info). The EU FBI covers 39 breeding bird species. Many other groups of species in agricultural areas are also declining: butterflies for example. The trend in the FBI of the Netherlands is clearly more negative than in the EU indicator. However, the causes of the decline throughout the EU are roughly the same as in the Netherlands. In eastern and southern Europe farmland bird habitats are mainly lost as agricultural activities in poor soil areas are being discontinued, and , the abandoned landbecomes encroached by shrubs and bushes rendering it unsuitable for farmland birds.