Introduction
Birds are among the easiest of animals to census. They are often brightly coloured, highly vocal at certain times of the year and relatively easy to see. They are also very popular, with the result that high-quality field guides are available in most parts of the world and there are many professionals and amateurs with a high level of identification skills. Because of this popularity, they are undoubtedly the most frequently surveyed of all taxonomic groups. The widespread involvement of volunteers in many schemes makes bird surveys an extremely cost-effective way of monitoring the overall health of the environment, as demonstrated by the inclusion of an indicator based on wild-bird population trends in the UK Government’s list of headline indicators of sustainable development (Gregory et al. 2003, 2004c; Anon 2005; http://www.sustainabledevelopment.
gov.uk/indicators/headline/h13.htm) and among the European Union’s structural
and sustainability indicators (Gregory et al. 2005; http://epp.eurostat.cec.eu.int/portal/page?
pageid=1090,30070682,1090 33076576& dad=portal& schema=PORTAL).
Introduction
Birds are among the easiest of animals to census. They are often brightly coloured, highly vocal at certain times of the year and relatively easy to see. They are also very popular, with the result that high-quality field guides are available in most parts of the world and there are many professionals and amateurs with a high level of identification skills. Because of this popularity, they are undoubtedly the most frequently surveyed of all taxonomic groups. The widespread involvement of volunteers in many schemes makes bird surveys an extremely cost-effective way of monitoring the overall health of the environment, as demonstrated by the inclusion of an indicator based on wild-bird population trends in the UK Government’s list of headline indicators of sustainable development (Gregory et al. 2003, 2004c; Anon 2005; http://www.sustainabledevelopment.
gov.uk/indicators/headline/h13.htm) and among the European Union’s structural
and sustainability indicators (Gregory et al. 2005; http://epp.eurostat.cec.eu.int/portal/page?
pageid=1090,30070682,1090 33076576& dad=portal& schema=PORTAL).
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