Adults have more male-biased sex ratios than first-winter juveniles in wintering duck populations

Background The long-term monitoring of demographic changes in waterbird populations remains limited, but such information can be valuable for conservationists and waterbird managers. Biased sex ratios can indicate differences in survival rates between sexes. In particular, differences in the sex ratios of fledged juveniles and adults can provide insight into the development of male bias among populations. Methods In this study, we used data from individual birds captured over a 57-year period to assess the extent, and temporal variability in male bias in nine populations of ducks wintering in the United Kingdom: Gadwall (Mareca strepera), Northern Mallard (Anas platyrhynchos), Northern Pintail (Anas acuta), Common Pochard (Aythya ferina), Common Shelduck (Tadorna tadorna), Northern Shoveler (Spatula clypeata), Eurasian Teal (Anas crecca), Tufted Duck (Aythya fuligula), and Eurasian Wigeon (Mareca penelope). Results Overall, eight of these populations were significantly male-biased and adults were more male-biased than first-winter juveniles for all nine populations. The increased male bias among adults is consistent with the hypothesis that factors such as higher mortality of reproductive-age females during the breeding season is a major cause of male bias in duck populations. However, such predation cannot explain the male bias detected in first-winter juveniles in four of the populations. The temporal trends in male bias differed between adults and first-winter juveniles in Northern Mallard, Northern Pintail, Common Pochard, Common Shelduck, Eurasian Teal, Tufted Duck, and Eurasian Wigeon. Over the study period we found increased male bias among adult Northern Mallard, Northern Pintail, Common Pochard, Common Shelduck, and Tufted Duck as well as both adult and first-winter juvenile Northern Shoveler. Conclusions We provide evidence that among wintering duck populations, sex ratios are typically male-biased, with adults exhibiting stronger male-biased sex ratios than first-winter juveniles. Improved monitoring of sex ratios of wintering waterbirds would help to increase our understanding of changes in waterbird demography, population structure, and observed population trends; our study shows that birds caught during ringing projects can be a valuable source of such data.

An Assessment of Water bird species and associated water bird composition in the Haiderpur Wetland of Hastinapur Wildlife sanctuary Uttar Pradesh, India

Bird species are natural indicators of healthy ecosystem. Indian sub-continent contributes about 13% of the world avian species. A study was carried out between year 2017 and 2019, at Haiderpur wetland (Hastinapur wildlife sanctuary) along the Ganga River in Utter Pradesh. Total 66 water bird species belonging to 15 families were encountered. Among the water bird species 04 Vulnerable (Common Pochard, Black headed ibis, Sarus crane, Indian skimmer), 06 near threaten (River Lapwing, Northern lapwing, River tern, Painted stork, Woolly-necked Stork, Black-tailed Godwit) and 01 Endangered (Black-bellied Tern) waterbird species (as per IUCN records) were reported in the Haiderpur wetland area. The contribution of water migratory bird is about 29% in the study area. This area is contributing as birding site thus more focus on conservation of this site.

Assessing Habitat Suitability for the Common Pochard, Aythya Ferina (Anseriformes, Anatidae) at different Spatial Scales in Orel’ River Valley, Ukraine

The habitat suitability for the Common Pochard, a duck species in decline, was studied in the middle reaches of the Orel’ River, Central Ukraine, in 2015–2017. The ducks were counted on their breeding grounds with the use of the ground survey technique. The positions of individual birds were estimated by GPS and plotted on the Google Earth map. The Ecological Niche Factor Analysis (ENFA) was applied to assess the habitat suitability. Sentinel-2 image was used to extract 13 ecogeographical variables and to get two measures of the ecological niche (marginality and specialization). The ENFA procedure was applied twice at landscape and sub-landscape levels to describe the habitat selection across sequential spatial scales. Both the axes of marginality and specialization of the ecological niche of the species proved to be significantly different from the random alternatives. At landscape level, the distribution may be predicted with the use of Aerosol/Coastal, Vegetation and Hydrothermal Composite indices (marginality) and Modified Normalized Difference Water (MNDW) Index along with several vegetation indices (specialization). At sub-landscape level, MNDW played a crucial role. The importance of MNDW is mediated by the preference for the wetlands with the stretches of open water which are used by the ducks to initiate flight safely and to optimize diving possibilities. The ENFA is a reliable tool for the assessment of the habitat suitability and for setting the conservation priorities for the Common Pochard.

The status of waterbird populations of Chhaya Rann Wetland Complex in Porbandar, Gujarat, India

The present investigation was undertaken to study the diversity of wetland birds in Chhaya Rann (Gujarati: Deserted land) wetland complex, situated in the urban setting of Porbandar City, in the western state of Gujarat, India. Almost 70 species belonging to 21 families of wetland birds have been reported from here with an estimated count of 35,747 and 20,981 in the year 2016 and 2015 respectively. Anatidae and Scolopacidae represent the higher number of species (11 each) followed by Ardeidae (eight species) and Laridae (seven species). The wetland complex supports one IUCN Red Listed Vulnerable species (Common Pochard Aythya ferina), six Near Threatened species (Lesser Flamingo Phoeniconaias minor, Oriental Darter Anhinga melanogaster, Dalmatian Pelican Pelecanus crispus, Black-headed Ibis Threskiornis melanocephalus, Black-tailed Godwit Limosa limosa and River Tern Sterna aurantia), and 63 Least Concern species. The wetland meets the Criteria 5 and 6 for listing as a wetland of international importance under the Ramsar Convention.

Status of water birds in Haripura-Baur Reservoir, western Terai-Arc landscape, Uttarakhand, India

We surveyed water birds in Haripura-Baur Reservoir using total count method between 2013 and 2015. A total of 65 species were recorded representing eight orders and 14 families. Numerically Anatidae was the dominant family followed by Ardeidae and Scolopacidae. Common Coot Fulica atra, Red-crested Pochard Netta rufina, Common Pochard Aythya ferina, Gadwall Anas strepera, and Tufted Pochard Aythya fuligula were dominant species in the reservoir. The Shannon diversity of water birds was more or less consistent over the years and ranged between 2.56 (2013–14) and 2.23 (2015–16). The reservoir supports water birds having declining population trends globally (41% of species), including three Vulnerable (Asian Woollyneck Ciconia episcopus, Lesser Adjutant Leptoptilos javanicus, and Sarus Crane Grus antigone and four Near Threatened species (Oriental Darter Anhinga melanogaster, Painted Stork Mycteria leucocephala, Black-necked Stork Ephippiorhynchus asiaticus, and River Lapwing Vanellus duvaucelii). Bird species belong to four feeding guilds with the domination of the carnivore group. The current information is expected to serve as preliminary database of water birds for further research and monitoring.