Since 2004, Denmark has systematically monitored the abundance of avian species that form the basis for the designation of the European Union Special Protection Areas (SPAs), under the National Monitoring and Assessment Program for the Aquatic and Terrestrial Environment (NOVANA). The Birds and Habitats Directives require the designation of a network of SPAs as well as Special Areas of Conservation (SACs), where both SPAs and SACs are designated as Natura 2000 areas to protect designated species and habitats (including birds) that require special protection within the European Union. These areas contribute to maintaining biodiversity conservation at national and European levels.
The bird monitoring element of the NOVANA programme has the primary aim of monitoring the distribution, population size and trends of individual species in Denmark. It also provides the numerical basis for comparing the trends in abundance of individual species both within and outside EU Birds Directive Special Protection Areas (SPAs). In this way, the monitoring programme provides the basis for recommending measures to improve the conservation status of the individual species.
This year's NOVANA bird report presents results from the monitoring conducted during 2020-2021. The species review presents the status of all species based on the overall monitoring material. In 2019, Denmark submitted a status report and database to the EU Commission as required under Article 12 of the EU Birds Directive. For that purpose, the species review in the last NOVANA bird report was expanded to include information on short- and long-term trends in bird populations, changes in their distribution and threats that may affect their abundance and distributions (Holm et al. 2021). These results were also summarized in easily accessible comprehensible tables and diagrams (Fredshavn et al. 2019). This analysis has been continued in the present report and here updated with new data.
Breeding species
Of the 46 breeding bird species included in NOVANA, 42 were monitored during 2020-2021. These breeding species are monitored under two intensive monitoring programmes, Intensive 1 and Intensive 2, while great cormorants Phalacrocorax carbo are also monitored under a special separate programme. Intensive monitoring seeks to monitor population size and mainly takes place within those SPAs where the species contribute to the designation of the site. For some species, monitoring is nationwide.
Intensive 1 covers species that occur in, or are known to return to, recognised localities. Of the 34 species monitored under the Intensive 1 programme, eight species have shown declining trends, including Arctic tern Sterna paradisaea and dunlin Caldris alpina schinzii, 11 species shown stable or fluctuating trends, e.g. black tern Chlidonias niger and ruff Calidris pugnax, while a further 13 species, including spotted crake Porzana porzana and Caspian tern Hydroprogne caspia, have increased. Two species, hen harrier Circus cyaneus and golden plover Pluvialis apricaria, have disappeared as breeding birds in the NOVANA period 2004-2021.
Examples of featured species:
The Arctic Tern is the most widespread tern species in Denmark, typically breeding on small, uninhabited islands and islets scattered along all Danish coasts, except on Bornholm. The species is highly migratory, wintering around Antarctica. NOVANA monitoring shows the Danish breeding population of Arctic terns has declined since monitoring began in 2006. Dunlin breed in Denmark on wet, short-grazed saltmarshes and meadows, migrating via Western Europe to wintering grounds in North Africa. This species used to be a more common Danish breeding bird, but during the 20th century the species has steadily declined, and is now restricted to a few large saltmarsh areas in Western Denmark and small, isolated sites on the islands. Black terns breed in colonies on wet meadows with reeds and sedges, as well as in lakes and marshes with abundant floating surface vegetation; they winter in West Africa.
Black terns were formerly more common than at present, but have declined rapidly in the 20th century, today restricted to very few nesting areas in Jutland. In 2021, between 57 and 71 pairs were registered and the population trend since 2004 has been stable, but fluctuating. The ruff breeds in Denmark on short-grazed saltmarshes with pans and rushes, as well as locally on freshwater meadows and winters in West Africa. It used to be common, except on Bornholm, but has declined considerably during the 20th century due to intensification of agriculture. In 2020, just 14 breeding pairs were registered, a sharp decrease compared to 2018, when 41 pairs were reported. Spotted crakes breed in larger swamp areas and freshwater meadows subject to natural, periodic flooding and they winter in East Africa. The species was common in the 1800s and widespread throughout the country, but declined greatly through the 1900s due to drainage and destruction of breeding habitats. In NOVANA's 2021 monitoring, 48 singing males were recorded in the SPAs where the species is one of the designation criteria. This represents a slight increase over the period since 2004. Caspian terns breed on islands and islets along the coasts and forage in lakes and shallow coastal areas, overwintering in West Africa. The species recolonised Denmark as a breeding bird in 2008 after having been absent for a number of years, and has since been registered every year in increasing numbers, with approximately 60 pairs in 2021.
The Intensive 2 programme covers rare or irregularly breeding species, as well as highly unpredictable nesting species. Of these, seven out of 11 species have increasing populations, e.g. Tengmalm’s owl Aegolius funereus and golden eagle Aquila chrysaetos. Two species, the Montagu’s harrier Circus pygargus and short-eared owl Asio flammeus, show stable trends and two species, the black stork Ciconia nigra and tawny pipit Anthus campestris, are considered to have gone extinct in the NOVANA period 2004-2021.
Tengmalm’s owls have been breeding regularly in Denmark since 2006, typically in woodpecker holes or in nest boxes provided in forest areas. The species occurs in Central Jutland, where it probably colonised from Germany, and on Bornholm, probably from Sweden. In 2021, six pairs were recorded breeding in the country. Golden eagles breed in tall, old trees in undisturbed areas. The species re-established itself as a Danish breeding bird in 1997-1999, when it succeeded in fledging two chicks. Subsequently, up to five pairs have bred in North Jutland. Montagu’s harrier breeds in winter cereal fields and on heathland with reedbeds, and winters in Africa. It was previously widespread in West and North Jutland, but declined sharply from the mid-1900s, and in 2021, 22 pairs were registered. The species requires large meadow areas as foraging area. Short-eared owls breed in large uncultivated areas with low vegetation, such as saltmarshes and along river floodplains, formerly also in marshes and heath areas. The species winters in Western Europe, including Denmark. Short-eared owls used to be common, but they are now very rare as a breeding bird, with between zero and six nesting pairs since 2004, with none since 2017 recorded under the NOVANA monitoring programme.
Migratory birds
Sixty-eight species of migratory birds were covered within the NOVANA monitoring programme during 2020-2021. Two of these are treated at subspecies level (bean goose Anser fabalis and brent goose Branta bernicla), which explains why a total of 70 taxa are included in the reporting. Among the 70 taxa, divers/loons (4 species) and auks (5 species) are only treated as species groups, as the majority of the observed birds cannot be identified from the air during aerial survey counts.
The majority of the treated species are included as one or more SPA designation criteria, but some other species are included, either because they will be part of the next Birds Directive Article 12 reporting in 2025 and/or are huntable species, e.g. greater white-fronted goose Anser albifrons, Canada goose Branta canadensis and mallard Anas platyrhynchos. The Canada goose is also an invasive species that is included in the national reporting to the African Eurasian Waterfowl Agreement.
Of the treated species, 45 species/subspecies are monitored in midwinter, achieved during a nationwide census in 2020 and under a so-called reduced midwinter census in Denmark in 2021. Some of these species are also monitored in other seasons, when they occur in greater numbers (e.g. Bewick’s swans Cygnus columbianus in spring and autumn, dabbling ducks in autumn), yet other species are primarily monitored in other seasons, especially waders, because with a few notable exceptions, most shorebirds overwinter outside the country.
The majority of the treated species have stable or fluctuating numbers (e.g. Bewick’s swan, goldeneye Bucephala clangula and goosander Mergus merganser) or are increasing (e.g. whooper swan Cygnus cygnus, almost all species of geese, several species of dabbling ducks) both in the shorter term (typically over the last 10-12 years) or longer period of time (back to the late 1960s or early 1980s – depending on the species group). In the case of the smew Mergellus albellus numbers have increased over a prolonged period, but in recent years numbers have been stable or fluctuating. For several marine species, trends in abundance over longer periods are difficult to assess due to gradual changes in count methods that were implemented in the 2000s. Some species have shown declining trends, including the scaup Aythya marila which has been in decline over a long period, while other species seem to have been in decline over the shorter time period, e.g. Bewick’s swan, taiga bean goose, pochard Aythya ferina and common scoter Melanitta nigra. Many of the wintering waterbird species fluctuate in numbers depending on the severity of the winter, with low numbers in cold winters and greater abundance in mild winters. For example, this is the case for Bewick’s swan and coot Fulica atra, although the latter seems to have been in marked decline since the early 2000s, despite relatively mild weather in the majority of winters over the past 20 years. Apart from mallard, the number of dabbling ducks in winter is also strongly dependent on the weather, and the increasingly frequency of milder winters has resulted in more and more dabbling ducks wintering in Denmark, this is especially the case for Eurasian wigeon Mareca penelope, gadwall Anas strepera, Eurasian teal A. crecca and northern pintail A. acuta, but also for northern shoveler Spatula clypeata. For the first time in the winter of 2020, Eurasian wigeon became the most numerous dabbling duck species in Denmark, with 105,000 birds counted, beating the mallard that had held that record in all other 15 winters based on nationwide counts from 1968-2016. Most of the waders have shown fluctuating numbers, making the assessment of population trends difficult, but Eurasian oystercatchers Haematopus ostralegus and red knot Calidris canutus seem to show declining trends.
For the first time in many years, this report provides modelled estimates of national numbers of divers/loons, selected diving ducks (common eider Somateria mollissima, common scoter, velvet scoter Melanitta fusca, long-tailed duck Clangula hyemalis and red-breasted merganser Mergus serrator) and auks. These are all species that are counted in particularly large numbers in marine areas which are covered by transect counts from aircraft. In the case of the velvet scoter, this is the first time there has been sufficient data to generate such modelled estimates. The new estimates for divers/loons and most of the diving duck species show that their levels of abundance are comparable with those from 2004 and 2008, and while numbers of auks also seem to be fluctuating without trend. However, common scoter numbers seem to be in decline.
We have adopted a new map design for 2020 and 2021 data presentation in this NOVANA report. The maps provide an immediate visual impression of where the largest numbers of a given species occur in the country, including the number counted in individual SPAs. A table provided under each map also provides statistics on the proportion of the population that has been counted in SPAs and in the Natura 2000 area network as a whole. These statistics can be used directly to support the next round of Article 12 reporting. However, for the marine species whose numbers have been calculated using modelling, we have yet to calculate the proportions within the SPAs.
Across all the species shown in Figure 1, it is evident that the vast majority of species enjoy a high degree of protection, with 60% or more of the birds counted within the SPAs, and for most species that a high proportion occurs in areas designated for the species. The species that appear to have the lowest proportion counted within protected areas are whooper and Bewick’s swans and most of the goose species, but this is because these species forage on arable farmland to a large extent and are most often counted on such areas during daytime. Many of these birds are counted on the fringe of many of SPAs, which they typically use for roosting. This was the case, for example, for the pink-footed goose Anser brachyrhynchus count from November 2021, where the percentage of birds registered in protected areas was extremely high because of a coordinated effort to monitor the numbers of geese travelling at the dusk flight to the overnight roosting sites.
An additional six species (Slavonian grebe Podiceps auritus, merlin Falco columbarius, lapwing Vanellus vanellus, jack snipe Lymnocryptes minimus, Iceland gull Larus glaucoides and glaucous gull Larus hyperboreus) are treated briefly in the report under the group "Other species". They are all scarce wintering species to be included in the next Article 12 reporting.
For the sake of completeness, the report also mentions 5 species of birds of prey (white-tailed sea eagle Haliaeetus albicilla, hen harrier, golden eagle Aquila chrysaetos, osprey Pandion haliaetus and peregrine falcon Falco peregrinus), Kentish plover Charadrius alexandrinus, little gull Hydrocoloeus minutus and short-eared owl, which contribute to the designation criteria applied to SPAs in 2020-2021. These species will first be updated based on more recent data and treated in more detail in the NOVANA 2022-2023 report. The same applies to red-necked grebe Podiceps grisegena, northern fulmar Fulmarus glacialis, spotted redshank Tringa erythropus and great kkua, Stercorarius skua, species that have only been included in the designation criteria for some of the SPAs during 2022.
The present 2020-2021 report should be cited as:
Nielsen, R.D., Holm, T.E., Clausen, P., Bregnballe. T., Clausen, K.K., Petersen, I.K., Sterup, J., Balsby, T.J.S., Pedersen, C.L., Dalby, L., Mikkelsen, P., Mellerup, K.A. & Bladt, J. 2023. Fugle 2020-2021. NOVANA. Aarhus University, DCE - National Center for Environment and Energy. - Scientific Report No. 531. https://novana.au.dk/fugle/
For the full Article 12 reporting, reference is also made to Fredshavn, J.R., Holm, T.E., Sterup, J., Pedersen, C.L., Nielsen, R.D., Clausen, P., Eskildsen, D.P. & Flensted, K.N. (2019). Size and development of bird populations in Denmark - 2019. Article 12 reporting to the Bird Protection Directive. Aarhus University, DCE - National Center for Environment and Energy, Scientific Report No. 363. http://dce2.au.dk/pub/SR363.pdf
Holm, T.E., Nielsen, R.D., Clausen, P., Bregnballe. T., Clausen, K.K., Petersen, I.K., Sterup, J., Balsby, T.J.S., Pedersen, C.L., Mikkelsen, P. & Bladt, J. 2021. Fugle 2018-2019. NOVANA. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 350 s. - Videnskabelig rapport nr. 420. novana.au.dk/fugle
