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overvågning af de almindelige fuglearter i danmark 1975-2010 6 summary
common
bird census in denmark 1975-2010 this report presents results from the danish point count census for wintering birds in the period 1975/76-2009/10 and for breed- ing birds in the period 1976-2010. indices and
trends
for 104 breeding
species
and for 77 wintering
species
are calculated using the software trim (
trends
and indices for monitoring data) which is suitable for ana- lysing long time series of counts with many missing values. appendix 1 and 2 show the indices for breeding birds and wintering birds, respectively, as well as the scientific and danish names of all
species
. for each
species
the index is set to 100 in the first year with sufficient data to calculate an index. the appendices also show the population trend for each
species
, i.e. the mean annual percentual change in the index for the entire period, as well as the significance level of the trend. the point count census method is based on a free choice scheme and is conducted by volun- teers which select their own route consisting of 10-20 points. there are two independent annual counts, one during the winter season (from december 20th to january 20th), and one during the breeding season (from may 1st to june 15th). the habitat surrounding each point is characterized by ascribing each of the four quadrants around the point to one of 9 habitat categories. data may be submit- ted to birdlife denmark by filling out a paper form or by use of a web-based database called dofbasen. the number of censused routes has been rela- tively stable for the past two decades (fig. 2, 3a, 3b) and although routes are neither randomly nor systematically distributed, they are found in all parts of the country (table 2). in the point count census participants are also able to register observations of mam- mals, allowing calculation of indices and
trends
for four of the most
common
danish mammal
species
, namely brown hare, red fox, roe deer, and red squirrel, which can be found in appendix 3. systematic monitoring of
common
birds is carried out all across europe and is coordi- nated through the pan-european
common
bird monitoring scheme (pecbms), which is a joint initiative of the european bird cen- sus council, collecting data on population
trends
of 137
species
of
common
birds from 22 european countries. by compiling some of these data, this report shows a comparison of the population
trends
of 79
common
breed- ing bird
species
in eastern, western, and northern europe. furthermore these
trends
are compared to the
trends
found for danish breeding birds. results are shown in appen- dix 4 and 5. finally, this report presents a set of bird indicators, which are based on the danish breeding bird indices and a
species
selection methods developed by pecbms. the indica- tors describe the population trend of ‘farm- land birds’, ‘woodland birds’ and ‘all other
common
birds’, and are shown in fig. 6 and appendix 6. besides these three pecbms categories, a category including all 104 danish breeding bird
species
is shown. lists of all volunteers are shown in appendix 7-8 and indices and
trends
are shown graphi- cally in appendix 9 and 10. the administration of the
common
bird census is run by birdlife denmark with financial sup- port from the ministry of environment until 2014. special thanks to ebcc for providing us with data from all countries involved in the pecbms for our analyses.
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