Greater Scaup Aythya Marila Research Articles

Bycatch of Seabirds in the Polish Part of the Southern Baltic Sea in 1970–2018: A Review

Bycatch, the unintended capture of animals other than target fish, is one of the most important anthropogenic threats to seabirds worldwide. This problem has been relatively little studied, however. The southern Baltic Sea is one of the three areas worldwide with the highest gillnet bycatch. Forty-eight publications from the years 1982–2021 addressing the problem of seabird bycatch in the Polish Exclusive Economic Zone (PEEZ) of the Baltic Sea were analysed for the purposes of this paper. Twenty-eight bird species were identified in bycatch, 13 of which have threatened or near-threatened status on the European Red Bird List. The magnitude of the annual bycatch was estimated for three periods: 1970s — 47,000 birds, 1980s and 1990s — 39,800 and 2010s — 21,300 birds. The most frequently bycaught species in the 2010s were Long-tailed Duck Clangula hyemalis (9,000 ind. yearly), Greater Scaup Aythya marila (3,500) and Velvet Scoter Melanitta fusca (2,000). Acceptable mortality thresholds calculated using both the Potential Biological Removal (PBR) and the BirdLife International (BLT) methods were found to have been exceeded: for Long-tailed Duck by 175% (PBR) and by 1,061% (BLT); for Greater Scaup by 542% (PBR) and by 3,400% (BLT); for Velvet Scoter by 35% (PBR) and by 495% (BLT). All three species are listed as Vulnerable in Europe. Six distinct bycatch areas have been identified in the PEEZ. Bycatch mitigation is exceedingly difficult to implement: the only effective method currently employed to protect seabirds from bycatch in gillnets involves the temporary closure of bird hotspots to gillnet fishing.

Changes in numbers and distribution of wintering waterbirds around Gotland 1969–2020

The coastal areas of the island of Gotland in the center of the Baltic Sea is an important wintering site for waterbirds in Sweden. Gotland offers extensive areas of shallow feeding grounds and, due to its location, some open waters remain available even during harsh winters. Wintering waterbirds have been counted annually on the island since the start of the International Waterbird Census in 1967, with full coverage of all the inshore areas around the main island obtained during the years 1969–1978 and 2013–2020. Between these two periods, the mean total number of wintering waterbirds increased from 32,000 to 111,500. The most numerous species were Mallard Anas platyrhynchos, Tufted Duck Aythya fuligula, and Common Goldeneye Bucephala clangula. Some species such as Eurasian Wigeon Mareca penelope, Eurasian Teal Anas crecca, and Gadwall Mareca strepera started to winter during the second period. Marked increases were also found for Smew Mergellus albellus and Greater Scaup Aythya marila, likely related to progressively milder winters in recent years.

Inventory of Lowland-Breeding Birds on the Alaska Peninsula

AbstractWe conducted the first systematic inventory of birds in the lowlands (areas ≤100 m above sea level) of the Alaska Peninsula during summers of 2004–2007 to determine their breeding distributions and habitat associations in this remote region. Using a stratified random survey design, we allocated sample plots by elevation and land cover with a preference for wetland cover types used by shorebirds, a group of particular interest to land managers. We surveyed birds during 10-min counts at 792 points across 52, 5 km × 5 km sample plots distributed from south of the Naknek River (58.70°N,157.00°W) to north of Port Moller (56.00°N,160.52°W). We detected 95 bird species including 19 species of shorebirds and 34 species (36% of total) considered at the time to be of conservation concern for the land managers in the region. The most numerous shorebirds on point counts were dunlin Calidris alpina, short-billed dowitcher Limnodromus griseus, and Wilson's snipe Gallinago delicata. We found the breeding-season endemic marbled godwit Limosa fedoa beringiae at 20 plots within a 3,000-km2 area from north of Ugashik Bay to just north of Port Heiden and east to the headwaters of the Dog Salmon and Ugashik rivers. The most abundant passerines on point counts were American tree sparrow Spizelloides arborea, Lapland longspur Calcarius lapponicus, and savannah sparrow Passerculus sandwichensis. Sandhill crane Antigone canadensis, glaucous-winged gull Larus glaucescens, and greater scaup Aythya marila were also relatively abundant. We categorized habitat associations for 30 common species and found that lowland herbaceous vegetation supported wetland-focused species including sandhill crane, marbled godwit, short-billed dowitcher, and dunlin; whereas, dwarf shrub-ericaceous vegetation supported tundra-associated species such as willow ptarmigan Lagopus lagopus, rock sandpiper Calidris ptilocnemis, and American pipit Anthus rubescens. Tall shrub vegetation was important to several species of warblers and sparrows, as well as one species of shorebird (greater yellowlegs Tringa melanoleuca). We found that point counts augmented with incidental observations provided an almost complete inventory of lowland-breeding species on the study area. These data form a baseline to monitor any future changes in bird distribution and abundance on the Alaska Peninsula.

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.

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), Bean Goose Anser fabalis (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.

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.

Analysis of wetland Birds as seen in Yamuna river at Okhla (Delhi), Faridabad and Palwal Districts in Haryana, India

The present studies were done during 2008-11 for the observations of wetland birds in River Yamuna at Okhla (Delhi), Faridabad and Palwal districts in Haryana. Visits were made in an irregular manner. In all 2 visits were made at Faridabad; village Chandhat nearby Palwal and at Hodal nearby village Kulena. It is pertinent to mention that few visits were made in winter season at Okhla barrage in New Delhi. In all, 60 species were recorded belonging to 8 orders and 14 families. Out of these 60 species of wetland birds, 35 were winter migratory, 11 local migratory and 11 species of birds were resident. The specific wetland birds specific to Yamuna River between “Delhi-Faridabad-Palwal” segments include Ferruginous Pochard Aythya nyroca, Black-headed Gull Larus ridibundus, Greater Scaup Aythya marila, River Tern Sterna aurantia and Pallas Gull Larus ichthyaetus. Other popular wetland birds include, amongst others, Mallard Anas platyrhynchos, Northern Pintail Anas acuta, Northern Shoveller Anas clypeata, Red-crested Pochard Rhodonessa rufina, Common Pochard Aythya ferina, Tufted Pochard Aythya fuligula, Bar-headed Goose Anser indicus, Greylag Goose Anser anser, Brahminy Shelduck Tadorna ferruginea, Gadwall Anas strepera, Eurasian Wigeon Anas penelope, White-tailed Lapwing Vanellus leucurus, Ruff Philomachus pugnax, Common Greenshank Tringa nebularia, Pallas Gull Larus ichthyaetus, Painted Stork Mycteria leucocephala, Open-billed Stork Anastomus oscitans, White-necked Stork Ciconia episcopus, Eurasian Spoonbill Platalea leucorodia, Black tailed Godwit Limosa limosa, Wood Sandpiper Tringa glareola, Little Stint Calidris minuta, Common Redshank Tringa totanus, Spotted Redshank Tringa erythropus and Pied Avocet Recurivirostra avosetta.Black-headed Gulls were seen in thousands followed by Greylag Goose Anser anser, Northern Shoveller, Northern Pintail etc. Minimum number noticed were those of Greater Scaup, Ferruginous Pochards etc. Resident wetland birds include Little Cormorants Phalacrocorax niger, Median Cormorants Phalacrocorax fuscicollis, Large Cormorants Phalacrocorax carbo , Pond Herons Ardeola grayii, Night Herons Nycticorax nycticorax, Black winged Stilts Himantopus himantopus, Common Moorhens Gallinula chloropus, Bronze-winged Jacana Metopidius indicus, Red-wattled Lapwing Vanellus indicus, Grey Herons Ardea cinerea, large Egrets Ardea alba and Median Egrets Mesophoyx intermedia. However, Grey Herons were seen only in 2-3 numbers. It seems that most of the popular migratory birds, perhaps, prefer Jheels, Lakes, Barrages compared to Yamuna river stream. Birds in Yamuna are not continuous in their availability. Rather birds are encountered at specific spots only in a given segment. Painted Storks were seen in 1or 2 and that too in the vicinity of Yamuna region rather than its stream of water. However, birds were seen in innumerous numbers at Okhla Barrage in Yamuna River nearby Delhi.

Characteristic of Bird Community Arriving in Sihwa Lake

This study was conducted in the region of Lake Sihwa between January and December of 2009, once every month, in order to assess the area's avian fauna. The result of the study showed 106,430 individuals (Sum of maximum count) of 153 species, 38 families and 14 orders. Dominants species included, in decreasing order, the mallard Anas platyrhynchos (18.2%), dunlin Calidris alpina (14.5%), greater scaup Aythya marila (11.1%), pochard Aythya ferina (8.2%) and the Eurasian wigeon Anas penelope (6.3%). Diversity Index was the highest in April at 3.00 and the lowest in November at 2.15. Evenness Index was the highest in May at 0.73 and the lowest in March at 0.53. Richness Index was the highest in April at 7.54 and the lowest in November at 4.47.

Jamaica Bay Studies IV: Factors Affecting Distribution of Greater Scaup Aythya marila in a Coastal Estuary in New York, USA

Jamaica Bay Studies IV: Factors Affecting Distribution of Greater Scaup Aythya marila in a Coastal Estuary in New York, USA