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overvågning af de almindelige fuglearter i danmark 1975-2011 6 summary common bird
census
in denmark 1975-2011 this report presents results from the danish point count
census
for wintering birds during the period 1975/76-2010/11 and for
breeding
birds during the period 1976-2011. indices and trends for 104
breeding
species
and for 77 wintering
species
are calculated using the soft- ware trim (trends and indices for monitor- ing data) which is suitable for analysing long time series of counts with many missing values. appendix 1 and 2 show the indices for
breeding
birds and wintering birds, respect ively, 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 popula- tion trend for each
species
, i.e. the mean an- nual percentual change in the index for the entire period, as well as the significance level of the trend. an overview of long term trends and short term trends (last 10 year period) is shown for each
species
in appendix 3 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 nine 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
census
ed routes has been rela- tively stable for the past two decades (fig. 1, 2a, 2b) 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 asked to register observations of mammals, al- lowing calculation of indices and trends for four of the most common danish mammal spe- cies, namely brown hare, red fox, roe deer, and red squirrel, which can be found in ap- pendix 4. this report comments on the results obtained by the common bird
census
for a number of the included
breeding
birds and wintering birds. finally, this report presents a set of bird in- dicators, which are based on the danish
breeding
bird indices and a
species
selection method 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. 3 and appendix 5. besides these three pecbms cate gories, a category including all 104 dan- ish
breeding
bird
species
is shown. lists of all volunteers are shown in appendix 6 and 7 and indices and trends are shown graphi- cally in appendix 8 and 9. the administration of the common bird
census
is run by dof-birdlife denmark with finan- cial support from the ministry of environment until 2014.
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