No. 232: Nielsen, H.H. & Clausen, P. 2022. Ynglende og rastende fugle i Vejlerne 2020. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 56 s. - Teknisk rapport nr. 232. http://dce2.au.dk/pub/TR232.pdf
Since 2007, the Aage V. Jensen Nature Foundation (AVJNF) and the Department of Ecoscience, Aarhus University have had an agreement to undertake annual monitoring of selected breeding and migratory birds at the Foundation’s Vejlerne reserve. The purpose of the bird monitoring in Vejlerne is to provide an annual status for a number of selected breeding and migratory birds in Vejlerne. The aim of the report here is to inform both AVJNF, the Vejlerne Reserve Management Board, authorities and the public about the results, as well as describe any reasons for observed changes in the number and distributions of the birds.
In Vejlerne, an extensive bird monitoring is carried out, and includes annual registrations of more breeding bird species than the National Monitoring and Assessment Programme for the Aquatic and Terrestrial Environment (NOVANA), whose primary focus is species mentioned in Annex 1 of the EU Birds Directive. It also involve that staging and wintering birds are monitored all year round, where most species in the NOVANA programme are only monitored in the months when the national population expected is greatest. In the years and months when species are monitored by NOVANA, the observers in Vejlerne contribute to this. Full details of the monitoring methods are given in more detail in the technical instructions, which are referenced in the report.
This report gives a detailed review of the breeding birds, and summary results of the monitoring of staging migratory species for 2020.
In 2020, record breeding numbers were reported for great white egret, marsh harrier and common crane in Vejlerne. For several ground-nesting species, e.g. meadow-species such as lapwing, black-tailed godwit, redshank, ruff, dunlin and arctic tern numbers in 2020 were at or below the levels observed in the previous ten years (2010-2019), although their levels of abundance remained below those of earlier years (1978-2003). Avocet had a good breeding season with almost twice the number recorded in 2019, the latter being a poor breading year. Numbers of breeding black tern have also been steadily declining since the late 1970s and the 24 pairs that attempted to breed in 2020 failed to raise offspring. For several of the breeding meadow species, whose numbers for many species peaked during 2000-2003 when fox numbers were low, the low numbers in recent years may be the result of dry springs and summers, in combination with high local predation pressure. Tables 3 to 5 of the report highlight the significance of Vejlerne for breeding birds in an international and national perspective. Two species, Eurasian bittern and dunlin from the Baltic population breed in numbers that exceed international 1% population criteria and many other species have far more than 1% of the national population.
Amongst the staging migrants 2020 had record numbers of great white egret, gadwall and common crane, as well as generally high numbers for dabbling ducks in spring compared to numbers during 2008-2019 (cf. Nielsen & Clausen 2019a,b, 2020). Bewick’s swans and taiga bean goose were largely absent, while Eurasian spoonbill were counted in relatively low numbers compared to previous years. In March there were over 30,000 geese in the area, mostly pink-footed and barnacle geese, but also more than 1,000 greater white-fronted geese, and 16,800 grey-lag geese were counted during moult in June. Many species occurred in 2020 in numbers that exceeded international or national 1 % of flyway population criteria (Table 6).
