Waterbird counts on large water bodies: comparing ground and aerial methods during different ice conditions

The aerial and ground methods of counting birds in a coastal area during different ice conditions were compared. Ice coverage of water was an important factor affecting the results of the two methods. When the water was ice-free, more birds were counted from the ground, whereas during ice conditions, higher numbers were obtained from the air. The first group of waterbirds with the smallest difference between the two methods (average 6%) contained seven species: Mute Swan Cygnus olor, Whooper Swan Cygnus cygnus, Greater Scaup Aythya marila, Tufted Duck Aythya fuligula, Common Goldeneye Bucephala clangula, Smew Mergellus albellus and Goosander Mergus merganser; these were treated as the core group. The second group with a moderate difference (average 20%) included another six species: Mallard Anas platyrhynchos, Eurasian Wigeon Mareca penelope, Common Pochard Aythya ferina, Great Crested Grebe Podiceps cristatus and Eurasian Coot Fulica atra. The third group with a large difference (average 85%) included five species, all of the Anatini tribe: Gadwall Mareca strepera, Northern Pintail Anas acuta, Northern Shoveler Spatula clypeata, Eurasian Teal Anas crecca and Garganey Spatula querquedula. During ice conditions, smaller numbers of most species were counted from the ground. The exception here was Mallard, more of which were counted from the ground, but the difference between two methods was relatively small in this species (7.5%). Under ice-free conditions, both methods can be used interchangeably for the most numerous birds occupying open water (core group) without any significant impact on the results. When water areas are frozen over, air counts are preferable as the results are more reliable. The cost analysis shows that a survey carried out by volunteer observers (reimbursement of travel expenses only) from the land is 58% cheaper, but if the observers are paid, then an aerial survey is 40% more economical

R codes for quantifying a mass mortality event in freshwater wildlife within the Lower Odra River

<p>In the summer of 2022, the Odra River in Europe was struck by an ecological calamity. Toxins from Golden Algae led to an unprecedented mass die-off of fish, bivalves, and aquatic snails. It is estimated that around 65 million bivalves perished, translating to an 88% reduction in the population of Unionidae mussels. The native species <i>Anodonta anatina</i> was particularly affected, witnessing a 95% decline. The invasive mussel <i>Sinanodonta woodiana</i> suffered the least damage, underscoring the potential of invasive species to fill the ecological void left by native mussels. The disaster also resulted in at least 147 million dead aquatic snails being washed ashore, marking an 85% decrease in their population. Around 3.3 million dead fish (1,025 tons) were found in the river's lower section, indicating a significant 64% drop in the biomass of the fish population across the impacted stretch.</p><p>• The text presents codes for analysis and modeling of the disaster using the R programming language.</p><p>• Only open-source software was utilized for the analysis.</p><p>• The analysis includes detailed data on the disaster's impact on various species.</p&gt

Management of Marine Natura 2000 Sites as Exemplified by Seabirds Wintering in the Baltic Sea: The Case of Poland

Based on the example of wintering waterbirds in the Baltic Sea, we show an approach that is useful in defining priority species for management. The Value Factor (VF) is the quantitative method for evaluating the importance of an area for a species. Every year, 4,400,000 waterbirds winter in the Baltic. Among these, the highest priority species are velvet scoter Melanitta fusca (hereafter VS, VF = 153) and long-tailed duck Clangula hyemalis (hereafter LTD, VF = 204): 74% and 40%, respectively, of the world’s populations, and over 90% of the EU populations of both species spend the winter in the Baltic. Management plans (hereafter MP) regulating the protection of marine Natura 2000 sites (hereafter MPA) and dedicated to the protection of VS and LTD have been implemented in 65% and 51%, respectively, of MPAs in the Baltic. Poland, a key country for the survival of these species, has not implemented a single MP despite the existence of documentation confirming their crucial importance for seaducks, and the pressures occurring there. We suggest using the VF concept to define priority species. On this basis, it will be possible to identify gaps in the protection of the most seriously threatened species and implement conservation measures at the most appropriate sites

Management of Marine Natura 2000 Sites as Exemplified by Seabirds Wintering in the Baltic Sea: The Case of Poland

Based on the example of wintering waterbirds in the Baltic Sea, we show an approach that is useful in defining priority species for management. The Value Factor (VF) is the quantitative method for evaluating the importance of an area for a species. Every year, 4,400,000 waterbirds winter in the Baltic. Among these, the highest priority species are velvet scoter Melanitta fusca (hereafter VS, VF = 153) and long-tailed duck Clangula hyemalis (hereafter LTD, VF = 204): 74% and 40%, respectively, of the world’s populations, and over 90% of the EU populations of both species spend the winter in the Baltic. Management plans (hereafter MP) regulating the protection of marine Natura 2000 sites (hereafter MPA) and dedicated to the protection of VS and LTD have been implemented in 65% and 51%, respectively, of MPAs in the Baltic. Poland, a key country for the survival of these species, has not implemented a single MP despite the existence of documentation confirming their crucial importance for seaducks, and the pressures occurring there. We suggest using the VF concept to define priority species. On this basis, it will be possible to identify gaps in the protection of the most seriously threatened species and implement conservation measures at the most appropriate sites

Ducks change wintering patterns due to changing climate in the important wintering waters of the Odra River Estuary

Some species of birds react to climate change by reducing the distance they travel during migration. The Odra River Estuary in the Baltic Sea is important for wintering waterfowl and is where we investigated how waterbirds respond to freezing surface waters. The most abundant birds here comprise two ecological groups: bottom-feeders and piscivores. Numbers of all bottom-feeders, but not piscivores, were negatively correlated with the presence of ice. With ongoing global warming, this area is increasing in importance for bottom-feeders and decreasing for piscivores. The maximum range of ice cover in the Baltic Sea has a weak and negative effect on both groups of birds. Five of the seven target species are bottom-feeders (Greater Scaup Aythya marila, Tufted Duck A. fuligula, Common Pochard A. ferina, Common Goldeneye Bucephala clangula and Eurasian Coot Fulica atra), and two are piscivores (Smew Mergellus albellus and Goosander Mergus merganser). Local changes at the level of particular species vary for different reasons. A local decline of the Common Pochard may simply be a consequence of its global decline. Climate change is responsible for some of the local changes in the study area, disproportionately favoring some duck species while being detrimental to others

Long-term changes in the numbers of waterbirds at an important European wintering site

Waterbirds were regularly monitored in north-western Poland from 2002 to 2018. Counts took place in the most important areas where wintering waterbirds concentrate in this region, the most important wintering ground for this group of birds in Poland and one of the most important in Europe. In addition to the wintering function, this area also has a very important function as a stopover site for significant numbers of African-Eurasian Flyway migrants. The average number of all waterbirds covered by the study from 2002 to 2018 was 117,000. Numbers in recent years (2011–2018) have increased significantly (P < 0.001) compared to the first half of the study (2002–2010). The most important species found here during the non-breeding period were: Greater Scaup Aythya marila (mean number for 2002–2018: 20,600), Tufted Duck A. fuligula (26,700), Common Pochard A. ferina (1,500), Smew Mergellus albellus (1,400), Goosander Mergus merganser (7,700), Great Crested Grebe Podiceps cristatus (840), Eurasian Coot Fulica atra (8,400), Mute Swan Cygnus olor (1,100), Whooper Swan C. cygnus (890), Taiga/Tundra Bean Goose Anser fabalis sensu lato (13,000) and White-fronted Goose A. albifrons (6,500). The importance of this region at the European scale for migratory and wintering waterbirds has increased, and this presents new challenges to the institutions responsible for protecting these areas.Od 2002 do 2018 roku prowadzono regularny monitoring ptaków wodnych w północno-zachodniej Polsce. Liczenie przeprowadzono w najważniejszych miejscach zimowania ptaków wodnych w tym regionie, będących jednocześnie ważnymi zimowiskami w Polsce i Europie. Poza funkcją zimowiska, miejsca te jednocześnie są ważnymi miejscami przystankowymi dla migrantów przelatujących z Euroazji do Afryki. Średnia liczba wszystkich ptaków wodnych w latach 2002–2018 na badanym obszarze wynosiła 117 000 osobników. W porównaniu z latami 2002–2010 w ostatnich ośmiu sezonach zimowych (lata 2011–2018) znacząco wzrosła liczba zimujących ptaków na Pomorzu Zachodnim. Najważniejszymi gatunkami obserwowanymi na badanym obszarze w okresie pozalęgowym były: ogorzałka Aythya marila (średnio 20 600 osobników), czernica A. fuligula (26 700), głowienka A. ferina (1500), bielaczek Mergellus albellus (1400), nurogęś Mergus merganser (7700), perkoz dwuczuby Podiceps cristatus (840), łyska Fulica atra (8400), łabędź niemy Cygnus olor (1100), łabędź krzykliwy C. cygnus (890), gęś zbożowa/tundrowa Anser fabalis sensu lato (13 000) i gęś białoczelna A. albifrons (6500). Znaczenie tego regionu dla ptaków migrujących i zimujących w skali Europy rośnie, co tworzy nowe wyzwania dla instytucji odpowiedzialnych za ochronę tych obszarów

Correction: The Importance of Non-Native Prey, the Zebra Mussel Dreissena polymorpha, for the Declining Greater Scaup Aythya marila: A Case Study at a Key European Staging and Wintering Site.

The European population of Greater Scaup Aythya marila has experienced an alarming, ~60% decline in numbers over the last two decades. The brackish lagoons of the Odra River Estuary (ORE) in the south-western Baltic Sea, represent an important area for the species during the non-breeding season in Europe. The lagoons regularly support over 20 000 Scaup, with peaks exceeding 100 000 (38%-70% of the population wintering in NW Europe and the highest number recorded in April 2011-105 700). In the ORE, Scaup feed almost exclusively on the non-native Zebra Mussel Dreissena polymorpha. This mussel was present in the ORE already in the 19th century and continues to be superabundant. Using the results of 22 Scaup censuses (November to April 2002/2003 to 2013/2014) from the whole ORE (523 km2 of water), we show that Scaup flocks follow areas with the greatest area of occurrence and biomass of the Zebra Mussel, while areas with low mussel densities are ignored. The numbers of Scaup in the ORE are primarily related to the area of Zebra Mussel occurrence on the lagoon's bottom (km2) in a non-linear fashion. Zebra Mussels were absolutely prevalent (97% of biomass) in the digestive tracts of birds unintentionally by-caught in fishing nets (n = 32). We estimate that Scaup alone consume an average of 5 400 tons of Zebra Mussels annually, which represents 5.6% of the total resources of the mussel in the ORE. Our results provide a clear picture of the strong dependence of the declining, migratory duck species on the non-native mussel, its primary food in the ORE. Our findings are particularly important as they can form the basis for the conservation action plan aimed at saving the north-western European populations of Scaup