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.

Population genomics indicate three different modes of divergence and speciation with gene flow in the green-winged teal duck complex

The processes leading to divergence and speciation can differ broadly among taxa with different life histories. We examine these processes in a small clade of ducks with historically uncertain relationships and species limits. The green-winged teal (Anas crecca) complex is a Holarctic species of dabbling duck currently categorized as three subspecies (Anas crecca crecca, A. c. nimia, and A. c. carolinensis) with a close relative, the yellow-billed teal (Anas flavirostris) from South America. We examined divergence and speciation patterns in this group, determining their phylogenetic relationships and the presence and levels of gene flow among lineages using both mitochondrial and genome-wide nuclear DNA obtained from 1,393 ultraconserved element (UCE) loci. Phylogenetic relationships using nuclear DNA among these taxa showed A. c. crecca, A. c. nimia, and A. c. carolinensis clustering together to form one polytomous clade, with A. flavirostris sister to this clade. This relationship can be summarized as (crecca, nimia, carolinensis)(flavirostris). However, whole mitogenomes revealed a different phylogeny: (crecca, nimia)(carolinensis, flavirostris). The best demographic model for key pairwise comparisons supported divergence with gene flow as the probable speciation mechanism in all three contrasts (crecca−nimia, crecca−carolinensis, and carolinensis−flavirostris). Given prior work, gene flow was expected among the Holarctic taxa, but gene flow between North American carolinensis and South American flavirostris (M ~0.1 - 0.4 individuals/generation), albeit low, was not expected. Three geographically oriented modes of divergence are likely involved in the diversification of this complex: heteropatric (crecca−nimia), parapatric (crecca−carolinensis), and (mostly) allopatric (carolinensis−flavirostris). Ultraconserved elements are a powerful tool for simultaneously studying systematics and population genomics in systems like this.

Timing of pair formation and male acquisition of alternate plumage by three wintering dabbling ducks

Pair formation in ducks is thought to be influenced by the acquisition of breeding plumage, the occurrence of courtship display, or both. We examined the frequency of pair formation in Mallard (Anas platyrhynchos), Green-winged Teal (Anas crecca carolinensis), and Northern Shoveler (Spatula clypeata) in the central valley of California in relation to the frequencies of male attainment of breeding plumage and courtship display. Predictions related to two hypotheses are: (1) the timing of pair formation is directly related to the attainment of breeding (definitive alternate) plumage by males, and (2) frequencies of courtship display are highest during pair formation. Most female Mallard were paired by the end of October, with >80% in pairs by early December. Of Northern Shoveler, 90% were paired by early January and 90% of female Green-winged Teal were paired by early February. The highest rates of courtship display by Mallard were observed during October through November, by Northern Shoveler in November, and by Green-winged Teal in November through January. Courtship display was, therefore, relatively frequent at the same time as pair formation for all three species. Northern Shoveler spent less time in courtship display than the other two species. Most (90%) male Mallard had acquired alternate plumage by mid-November, Northern Shoveler by early February, and Green-winged Teal by mid-December. Thus, timing of pair formation coincided with timing of attainment of breeding plumage in Mallard and Green-winged Teal but not Northern Shoveler.

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.

Filoplume morphology covaries with their companion primary suggesting that they are feather-specific sensors

Do birds detect and respond to forces acting on feathers through filoplumes, which appear to be unique mechanosensory feathers? If filoplumes function as sensors, their morphology should covary with the morphology of their companion feather to better detect feather movements and position. We explore covariation in filoplumes and primaries across 5 species of birds that vary in body size, molt strategy, and the functional life span of their primaries (Green-winged Teal [Anas crecca], Ring-billed Gull [Larus delawarensis], Turkey Vulture [Cathartes aura], Red-tailed Hawk [Buteo jamaicensis], and Red-winged Blackbird [Agelaius phoeniceus]). Filoplumes never extended beyond the coverts and inserted immediately adjacent to the base of their companion primaries, positioning them to detect subtle changes in feather vibration or movement. Far more variation in filoplume number and morphology was due to species differences than to individuals or position in the wing. Across species, filoplume length and number increased with calamus length of primaries. In the 2 species with growing primaries, the number and length of filoplumes were only weakly associated with molting primaries, suggesting that filoplumes were not replaced when their companion primary was replaced. Further, filoplumes associated with a growing primary were not replaced synchronously, leaving others to sense primary position and movement. Finally, filoplume number and length were greatest in Red-tailed Hawks, a species that carries individual feathers for multiple years, but links between filoplume morphology and molt strategy await broader comparative studies. Taken together, the morphology of filoplumes and their replacement schedule relative to their associated primary suggests that they are sensors, capable of detecting subtle differences in the position and movement of their companion feathers.

Bioaccumulation of trace elements in migratory waterbirds at two wetlands of Indus river

Waterbirds are used as a bioindicator for analyzing wetland health because they are very sensitive to changes in ecosystems at the nutrient level and through exposure to pollutants. In the present study, bioaccumulation of trace elements (Cu, Zn, Ni, Pb, Co, Cd, and Mn) was investigated in Common Coot Fulica atra, Gadwall Anas strepera, and Eurasian Teal Anas crecca at Taunsa barrage and Chashma barrage located on Indus River, Punjab, Pakistan. Samples of water, sediments, and waterbirds tissues were collected during autumn 2018 and the spring of 2019. Metal concentrations were assessed by using a flame atomic absorption spectrophotometer (Thermo Scientific iCE 3000 Series). We found that the maximum bioaccumulation in birds was of cadmium. Order of metal accumulation was Cd > Pb > Zn > Co > Mn > Cu > Ni (Common Coot) and Cd > Pb > Zn > Co > Cu > Ni > Mn (Gadwall and Eurasian Teal) at Taunsa barrage. At Chashma barrage metal accumulation order was Cd > Zn > Pb > Co > Cu > Mn > Ni (Common Coot), Cd > Zn > Pb > Cu > Co > Ni > Mn (Gadwall) and Cd > Zn > Pb > Co > Cu > Ni > Mn (Eurasian Teal). A. crecca was the species in which the most of the trace elements (Cu, Ni, Pb, Co, and Mn) were accumulated at Taunsa barrage, while at Chashma barrage Zn, Pb, Cd, and Co accumulated in F. atra. Zn, Pb and Cd (avg. > 10) had a high bioaccumulation ratio and Co, Cu, Ni, and Mn (avg. < 10) had low bioaccumulation ratio. When tissues were compared for accumulation, the highest concentrations were observed in the intestine followed by gizzard, probably because of the feeding habits of these waterbirds.

Specimens of Aquatic Bird Deposited at Mosul Natural History Museum, Mosul, Iraq

There are (11) aquatic Birds specimens deposited at Mosul natural history Museum, these belong to five orders namely: order Ciconiiformes, Phoenicopteriformes, Pelecaniformes, Anseriformes and Caradiformes. Ciconiformes include Ardea purpurea, Egretta garzetta, Ciconia ciconia, Nycticorax nycticorax, Ixobrychus minitus. Order Phoenicopteriformes include Phoenicopterus aguorum, order Pelecaniformes include Pelecanus onocrotalus, order Anseriformes include Anas crecca and Anas platyrhynchos, Casarca ferruguinea and order Charadriiformes include ,Larus canus.

Differences in Highly Pathogenic H5N6 Avian Influenza Viral Pathogenicity and Inflammatory Response in Chickens and Ducks

Infection with H5N6 highly pathogenic avian influenza virus caused high mortality in chickens, while ducks often appear to be asymptomatic. But, some recent H5Nx subtype viruses could cause high mortality in ducks. The variation between different species and the mechanisms by which some H5Nx viruses cause death in ducks requires investigation to identify the key processes in influenza susceptibility and pathogenesis. Here, we characterized two representative H5N6 viruses, A/Pavo cristatus/Jiangxi/JA1/2016 (JA1) and A/Anas crecca/shanghai/SH1/2016 (SH1), and compared their pathogenicity and expression profiles of immune-related genes in chickens and ducks to identify the elements of the host immune-related response that were involved in disease lethality. Results suggested that H5N6 HPAIVs had higher pathogenic and inflammatory effect in chickens than in ducks. Importantly, the TNF-α, IL-6, IFN-γ and iNOS levels were significantly higher in the lung of SH1 infected chickens compared to those of ducks. And we found higher systemic levels of IL-6 induced by JA1 in chickens than in ducks. In addition, our experiments demonstrated that JA1 was associated with greater pathogenicity in ducks were accompanied by the excessive expression of iNOS in the brain. These results are helpful to understand the relationship between the pathogenicity of H5N6 AIVs and inflammatory responses to them in chickens and ducks.