The State of Europe's Common Birds 2008 - European Bird Census ...

The State of Europe’s Common Birds 2008Photo by D. Jirovský (wildbirdphoto.eu)Both papers represented a milestonein reference to PECBMS, mostly asa source of information about themethods used to calculate speciesindices and indicators.Another paper, published quiterecently (Gregory et al. 2008), usesexamples from the UK and Europe toillustrate the state of play regardingthe use of birds as indicators. The UKexperience provides an excellentexample of turning scientific data intopolicy measures in natureconservation, which has subsequentlybeen followed by other countries. Alsoat European level, the common birdindicators proved to be successful interms of use in policy and in fact theyrepresent one of very few fullyoperational biodiversity indicators inEurope.The Great Reed-warbler Acrocephalusarundinaceus is expected to benefit from climatechange (Gregory et al. 2009). In Poland, it hasalready been shown to be adapting well by shiftingits laying dates, probably to optimise foodresources (Dyrcz and Halupka 2009).from national or regional breeding birdmonitoring schemes can be analysed,supranational species indices can be generatedand multi-species indicators can be calculated byaveraging the resulting indices. The paper showedhow data collated by skilled volunteers and bymethods and survey designs that differ slightlybetween countries can be combined to producerelevant multi-national results. It also describedhow and why national species indices need to beweighted by population size in order to producerelevant supra-national figures. The paper alsoshowed that common farmland birds in Europehave declined steeply since 1980, and thatevidence elsewhere shows that the main driver offarmland bird declines is agriculturalintensification.The PECBMS European data werealso used for explorative analysis ofspecies trends, particularly of forestspecies (Gregory et al. 2007). This showed thatsince 1980, forest specialists have declinedmore than forest generalists, but trendsdiffered regionally, and interestingly forestspecies in Central and Eastern Europe haveshown stability or even increased. Anindependent study demonstrated that forestspecialists have increased in the CzechRepublic, most likely as a result of increasingforest coverage and age (Reif et al. 2007). AtEuropean level, among common forest birds,long-distance migrants and residents onaverage declined most strongly, whereas shortdistancemigrants were largely stable, or evenincreased. There was some evidence to suggestthat ground- or low-nesting species declinedmore strongly on average, as did forest birdswith invertebrate diets. It also appeared thatin a small number of species, year-to-yearvariation in abundance can be influenced bycold winters. However, much more researchneeds to be done to understand trends offorest bird species and their driving forces.22