Indicator Name: Wintering aquatic-habitat birds population trends

Assessment: Among the aquatic habitat birds in Serbia, 25 species of birds have been selected. Two indicators have been used to show the trend of their populations in Serbia – the size of nesting populations and the trend of the number of wintering populations of the entire set of species based on the results of the International Waterbird Census. The International Waterbird Census (IWC) has been in place in Europe since 1967, while in Serbia it was initiated in 1982, but only on the Danube, and not systematically every year. Since 2012, the Bird Protection and Study Society of Serbia has been coordinating this census. Since then, it has covered most of the larger aquatic bodies and watercourses with variations in coverage in specific years. Having in mind the above, only the results of the census from 2012 to 2017 were used to analyse the trends of wintering populations of aquatic bird species. The presented trends of abundance in percent are expressed in relation to the average abundance of the species for the covered period.

Wintering bird populations covered by the systematic census (2012-2017) during the short period of time, have undergone oscillations in numbers, mostly without a clearly visible general trend. Based on the territorial coverage and the recorded numbers, the expressed fluctuation of numbers in winter has been observed in a number of aquatic species (a total of 14 out of 25): Gavia arctica, Gavia stellata, Phalacrocorax carbo, Fulica atra, Alcedo atthis, Anser albifrons, Melanitta fusca, Ayth ferina, Aythya fuligula, Aythya marila, Anas crecca, Anas strepera, Anas penelope, Grus grus. These oscillations can be a reflection of a number of different factors, both broader, global trends in the populations of certain species, and climatic conditions and changes in ecosystems and direct threatening factors by humans, and only the results of long-term monitoring can indicate patterns and directions of phenomena and trends. Nevertheless, for the period covered by the detailed census conducted within the IWC, general observations can be made about the growing and declining trends of wintering bird populations. Based on the territorial coverage and the recorded numbers, a decrease in the number of winters has been recorded in three species: Tachybaptus ruficollis, Phalacrocorax pygmeus, Anas platyrhynchos. Based on the territorial coverage and the recorded numbers, an increase in numbers in winter periods from 2012 to 2017 has been observed in 8 out of 25 species of aquatic birds: Mergus merganser, Podiceps cristatus, Cygnus columbianus, Anser anser, Anas acuta, Bucephala clangula, Tadorna tadorna, Mergellus albellus. Out of these, for the species Mergellus albellus and Bucephala clangula, this was only a short-term increase, because the number, according to available data in the period before 2012, had been even higher in some winters. In addition to natural factors that lead to changes in numbers, the differences in numbers that we show can be a reflection (especially in the case of increasing trends) of ever increasing coverage of aquatic habitats by our census takers throughout Serbia, the use of better equipment (telescopes) and generally better experience of our census takers. Taking into account the above, the negative short-term trend in the mentioned three species of birds of aquatic habitats (Tachybaptus ruficollis, Phalacrocorax pygmeus, Anas platyrhynchos) is unambiguous.

Indicator Name: Wintering aquatic-habitat birds population trends

Institution/Author: Environmental Protection Agency/Slaviša Popović, Society for the Study and Protection of Birds/Milan Ružić, Dr Dimitrije Radišić 

Use and interpretation:

The indicator shows the trend of changes in the population abundance of selected bird species. The change in the population of birds explains the loss, and change in the structure of their habitats, due to fragmentation and isolation, as well as other changes in the environment that directly or indirectly affect the change in population structure.

Key question(s) which indicator helps to answer

The indicator helps to answer the question: What is the trend in population growth of selected species?

Use of indicator

Among the aquatic habitat birds in Serbia, 25 species of birds have been selected. Two indicators have been used to show the trend of their populations in Serbia – the size of nesting populations and the trend of the number of wintering populations of the entire set of species based on the results of the International Waterbird Census. The International Waterbird Census (IWC) has been in place in Europe since 1967, while in Serbia it was initiated in 1982, but only on the Danube, and not systematically every year. Since 2012, the Bird Protection and Study Society of Serbia has been coordinating this census. Since then, it has covered most of the larger aquatic bodies and watercourses with variations in coverage in specific years. Having in mind the above, only the results of the census from 2012 to 2017 were used to analyse the trends of wintering populations of aquatic bird species. The presented trends of abundance in percent are expressed in relation to the average abundance of the species for the covered period.

Scale of appropriate use

Number of population of selected bird species and population growth through the time and by habitats. Changes of the most important types of habits, according to CORINE Land Cover and EUNIS.

Potential for aggregation:

Meaning of upward or downward trends (“good or bad”)

The periodicity of data collection: Bird Protection and Study Society of Serbia collect and analyse data. The indicator also relates to trend in changing of the most important types of habitats according to CORINE Land Cover and EUNIS, which means dynamics of changes in the area of forest, meadows, mixed and other types of habitats.

Possible reasons for upward or downward trends:

The indicator is determined annually, and it is important for monitoring population growth of selected bird species.

Implications for biodiversity management of change in the indicator:

The indicator is traditionally described in annual state-of-the-environment reports in Serbia, and it is determined as biodiversity indicator, according to The Rulebook on the National list of environmental protection indicators (Official Gazette of the Republic of Serbia No. 37/2011).

Units in which it is expressed:

The number of individuals per unit area. Number of breeding pairs. Surface expressed in hectares (ha).

Description of source data:

Bird Protection and Study Society of Serbia

Calculation procedure:

Trend in changes of population abundance of selected species of birds according to the expert and administrative lists and methodology of counting and assessment developed by the European Agency for Environmental Protection. Dynamic of habitat changing of habitats according to EUNIS classification and / or the CORINE Land Cover methodology.

Most effective forms of presentation:

(graph types, maps, narratives, etc.-give examples where possible):

The best ways to present this indicator are tables and graphs and they provide opportunity to monitor progress regarding this indicator and to record trends observed.

Limits to usefulness and accuracy:

Access to data, slow data exchange and update

Updating the indicator:

Annually.

Closely related indicators:

Diversity of species-birds population trend

Additional information and comments:

Table: Wintering aquatic-habitat birds population trends

Serbia