Anas Platyrhynchos Research Articles

The incubation environment does not explain significant variation in heart rate plasticity among avian embryos.

The conditions an organism experiences during development can modify how they plastically respond to short-term changes in their environment later in life. This can be adaptive because the optimal average trait value and the optimal plastic change in trait value in response to the environment may differ across different environments. For example, early developmental temperatures can adaptively modify how reptiles, fish and invertebrates metabolically respond to temperature. However, whether individuals within populations respond differently (a prerequisite to adaptive evolution), and whether this occurs in birds, which are only ectothermic for part of their life cycle, is not known. We experimentally tested these possibilities by artificially incubating the embryos of Pekin ducks (Anas platyrhynchos domesticus) at constant or variable temperatures. We measured their consequent heart rate reaction norms to short-term changes in egg temperature and tracked their growth. Contrary to expectations, the early thermal environment did not modify heart rate reaction norms, but regardless, these reaction norms differed among individuals. Embryos with higher average heart rates were smaller upon hatching, but heart rate reaction norms did not predict subsequent growth. Our data also suggests that the thermal environment may affect both the variance in heart rate reaction norms and their covariance with growth. Thus, individual avian embryos can vary in their plasticity to temperature, and in contrast to fully ectothermic taxa, the early thermal environment does not explain this variance. Because among-individual variation is one precondition to adaptive evolution, the factors that do contribute to such variability may be important.

Human access constrains optimal foraging and habitat availability in an avian generalist.

Animals balance costs of antipredator behaviors with resource acquisition to minimize hunting and other mortality risks and maximize their physiological condition. This inherent trade-off between forage abundance, its quality, and mortality risk is intensified in human-dominated landscapes because fragmentation, habitat loss, and degradation of natural vegetation communities is often coupled with artificially enhanced vegetation (i.e., food plots), creating high-risk, high-reward resource selection decisions. Our goal was to evaluate autumn-winter resource selection trade-offs for an intensively hunted avian generalist. We hypothesized human access was a reliable cue for hunting predation risk. Therefore, we predicted resource selection patterns would be spatiotemporally dependent upon levels of access and associated perceived risk. Specifically, we evaluated resource selection of local-scale flights between diel periods for 426 mallards (Anas platyrhynchos) relative to wetland type, forage quality, and differing levels of human access across hunting and nonhunting seasons. Mallards selected areas that prohibited human access and generally avoided areas that allowed access diurnally, especially during the hunting season. Mallards compensated by selecting for high-energy and greater quality foraging patches on allowable human access areas nocturnally when they were devoid of hunters. Postseason selection across human access gradients did not return to prehunting levels immediately, perhaps suggesting a delayed response to reacclimate to nonhunted activities and thus agreeing with the assessment mismatch hypothesis. Last, wetland availability and human access constrained selection for optimal natural forage quality (i.e., seed biomass and forage productivity) diurnally during preseason and hunting season, respectively; however, mallards were freed from these constraints nocturnally during hunting season and postseason periods. Our results suggest risk-avoidance of human accessible (i.e., hunted) areas is a primary driver of resource selection behaviors by mallards and could be a local to landscape-level process influencing distributions, instead of forage abundance and quality, which has long-been assumed by waterfowl conservation planners in North America. Broadly, even an avian generalist, well adapted to anthropogenic landscapes, avoids areas where hunting and human access are allowed. Future conservation planning and implementation must consider management for recreational access (i.e., people) equally important as foraging habitat management for wintering waterfowl.

Local movements of farmed‐released versus wild mallards Anas platyrhynchos in fall

Releasing farmed mallards into the wild is a common practice in wildlife management worldwide, involving millions of birds annually, and is mainly carried out to increase hunting opportunities. Ringing and previous research show that released mallards have low survival also outside the hunting season, and that survivors may compromise migration habits, morphology, and adaptations of the wild population. Detailed local movements of released mallards have not been studied before, despite the importance of spatiotemporal patterns for understanding the impact of releases and their utility for hunting. We studied local movements in August–October of 11 wild and 44 released mallards caught in the same wetland in southern Sweden and provided with GPS tags. Wild mallards moved longer distances than farmed, over the whole diel cycle, as well as during three out of four separate periods of the day (dawn, day, and dusk). Mallards of both origins moved the longest distances during dusk and dawn, and the shortest during the night. Males and females did not differ significantly in distance moved, regardless of origin (wild versus farmed). Our study demonstrates large differences in spatiotemporal movement patterns between wild and farmed mallards. The typical day of wild mallards included movements between wetlands in the landscape, likely to foraging sites known from previous experience. However, wild mallards frequently returned to the study wetland, probably attracted by supplementary bait. On the other hand, farmed mallards seldom left the study wetland, despite the possibility of accompanying wild birds to other sites. The sedentary behavior of farmed mallards and the fact that wild birds come to join them are both beneficial for hunting purposes. Limited movements of farmed mallards, together with their low survival, could also be positive as they limit hybridization between wild and farmed mallards, as well as dispersal of nutrients.

Analysis of Chicken IFITM3 Gene Expression and Its Effect on Avian Reovirus Replication.

Interferon-inducible transmembrane protein 3 (IFITM3) is an antiviral factor that plays an important role in the host innate immune response against viruses. Previous studies have shown that IFITM3 is upregulated in various tissues and organs after avian reovirus (ARV) infection, which suggests that IFITM3 may be involved in the antiviral response after ARV infection. In this study, the chicken IFITM3 gene was cloned and analyzed bioinformatically. Then, the role of chicken IFITM3 in ARV infection was further explored. The results showed that the molecular weight of the chicken IFITM3 protein was approximately 13 kDa. This protein was found to be localized mainly in the cytoplasm, and its protein structure contained the CD225 domain. The homology analysis and phylogenetic tree analysis showed that the IFITM3 genes of different species exhibited great variation during genetic evolution, and chicken IFITM3 shared the highest homology with that of Anas platyrhynchos and displayed relatively low homology with those of birds such as Anser cygnoides and Serinus canaria. An analysis of the distribution of chicken IFITM3 in tissues and organs revealed that the IFITM3 gene was expressed at its highest level in the intestine and in large quantities in immune organs, such as the bursa of Fabricius, thymus and spleen. Further studies showed that the overexpression of IFITM3 in chicken embryo fibroblasts (DF-1) could inhibit the replication of ARV, whereas the inhibition of IFITM3 expression in DF-1 cells promoted ARV replication. In addition, chicken IFITM3 may exert negative feedback regulatory effects on the expression of TBK1, IFN-γ and IRF1 during ARV infection, and it is speculated that IFITM3 may participate in the innate immune response after ARV infection by negatively regulating the expression of TBK1, IFN-γ and IRF1. The results of this study further enrich the understanding of the role and function of chicken IFITM3 in ARV infection and provide a theoretical basis for an in-depth understanding of the antiviral mechanism of host resistance to ARV infection.

Mottled ducks, feral mallards, and their hybrids in Florida

AbstractThe nonmigratory and endemic Florida mottled duck (Anas fulvigula fulvigula) is facing conservation threats from the combined effects of urbanization and introgressive hybridization with feral mallards (Anas platyrhynchos) and mallard x mottled duck hybrids. In the past, the status of the Florida mottled duck population was assessed during annual aerial surveys and most brown ducks (mottled ducks, mallards, and hybrids of them) detected during the survey would have been mottled ducks. But the release of domesticated mallards for aesthetic purposes has led to increases in the prevalence of mallards‐hybrids (mallards or mallard x mottled duck hybrids) throughout peninsular Florida, USA, and because it is impossible to differentiate among mottled ducks, female mallards, and hybrids during aerial surveys, helicopter surveys were halted in 2009 until state researchers could conduct a range‐wide study to determine what proportion of brown ducks are mottled ducks versus mallards‐hybrids. We used plumage keys and high‐resolution photography to categorize brown ducks from 557 wetland grid points as either mottled ducks or mallards‐hybrids. Of the 5,179 brown ducks categorized, 40.1% were mottled ducks and 59.9% were mallards‐hybrids. We used logistic regression analysis to model the interactive effect of a site's latitude and level of urbanization (urban gradient value within a 2‐km buffer) to generate a predictive raster surface (1‐km resolution) of the study area with values corresponding to the probability that a brown duck observed within a cell is a pure mottled duck. Predicted values will be used as correction factors when estimating final mottled duck population abundance from brown‐duck survey data. Additionally, the predictive raster surface will be used to identify wetlands where mottled ducks remain predominant so that these sites can be targeted for preservation. Overall, mallards‐hybrids outnumbered mottled ducks throughout most of peninsular Florida, especially in more urbanized regions, and their current prevalence rate presents a serious conservation threat, via hybridization, to extant mottled duck populations.

Genome-wide characterization and comparison of endogenous retroviruses among 3 duck reference genomes

Endogenous retroviruses (ERV) are viral genomes integrated into the host genome and can be stably inherited. Although ERV sequences have been reported in some avian species' genome, the duck endogenous retroviruses (DERV) genome has yet to be quantified. This study aimed to identify ERV sequences and characterize genes near ERVs in the duck genome by utilizing LTRhavest and LTRdigest tools to forecast the duck genome and analyze the distribution of ERV copies. The results revealed 1,607, 2,031, and 1,908 full-length ERV copies in the Pekin duck (ZJU1.0), Mallard (CAU_wild_1.0), and Shaoxing duck (CAU_laying_1.0) genomes, respectively, with average lengths of 7,046, 7,027, and 6,945 bp. ERVs are mainly distributed on the 1, 2, and sex chromosomes. Phylogenetic analysis demonstrated the presence of Betaretrovirus in 3 duck genomes, whereas Alpharetrovirus was exclusively identified in the Shaoxing duck genome. Through screening, 596, 315, and 343 genes adjacent to ERV were identified in 3 duck genomes, respectively, and their functions of ERV neighboring genes were predicted. Functional enrichment analysis of ERV-adjacent genes revealed enrichment for Focal adhesion, Calcium signaling pathway, and Adherens junction in 3 duck genomes. The overlapped genes were highly expressed in 8 tissues (brain, fat, heart, kidney, liver, lung, skin, and spleen) of 8-wk-old Mallard, revealing their important expression in different tissues. Our study provides a new perspective for understanding the quantity and function of DERVs, and may also provide important clues for regulating nearby genes and affecting the traits of organisms.

AVIAN INFLUENZA A VIRUS SURVEILLANCE IN RESERVOIR DOMESTIC DUCKS (Anas platyrhynchos domesticus) IN MAIDUGURI METROPOLITAN COMMUNITY OF NORTH-EASTERN NIGERIA: A NEED FOR ONE-HEALTH APPROACH

The domestic ducks (Anas platyrhynchos domesticus) are natural reservoir hosts of avian influenza A virus (AIV) and have since remained significant in the ecology and epidemiology of the virus globally. Continued local surveillance for AIV in this specie is critical to assessing the risks of potential spreading to domestic poultry, other animal species, and zoonotic transmission to humans. In this study, we investigate the status of AIV in domestic waterfowls in Maiduguri metropolis. Twenty-eight cloacal and oropharyngeal swab samples were collected from apparently healthy domestic ducks from November to December 2021 in Bulumkutu (n=2), Giwa Barracks (n=5), Kasuwan Shanu (n=4), Maimalari Barracks (n=5), Mairi (n=5), Premier (n=2) and Shehuri (n=4). Samples were screened for AIV using the real-time RT-PCR molecular assay. A total prevalence of 60.7% (CI: 41.99 –77.32) was recorded. Prevalence based on locations was higher in Bulumkutu 100% (CI:22.36 - 100), Kasuwan Shanu 100% (CI: 22.36 - 100), and Shehuri 100% (CI:47.29 - 100). In Maimalari Barracks and Mairi, prevalence of 60% (18.24 – 92.65) each was recorded respectively. While samples from Giwa Barracks and Gomari had a prevalence of 40% (CI: 7.346 – 81.76) and 33.3% (1.667 – 86.8). AIV was not detected in samples from premier (0%). The result of this study revealed the status of AIV in domestic ducks in Maiduguri metropolis. Thus, this early warning call the need for AIV prevention and control in the region and using the one-health approach to access the zoonotic potential of the virus in the domestic ducks...

Time budget of a mallard duck population residing in an urban park in northern Portugal during courtship and nesting period

Behavioural observations were used to investigate the temporal dynamics events and associated variation in the daily activities of a sedentary population of mallard duck (Anas platyrhynchos) inhabiting an urban park in northern Portugal. Data was collected at Porto City Park from December to April, during the species’ courtship and early nesting periods. The most frequent activities for this population were locomotion, resting and feeding. Statistical analysis revealed that male and female behaviours differed significantly throughout the courtship period, as males exhibited more displays and aggressive behaviour while females were more prone to feed in order to meet their increased nutritional and energetic needs. Temporal analyses showed that courtship reached a peak in intensity in February, since it was in this month that the highest values for mating, aggressive behaviour in males and defensive behaviour in females were observed. Behavioural differences were found for this population, with higher feeding rates compared to those of wild populations as well as lower defensive behaviour rates. This paper sheds light on how synanthropized populations, as well as those from Southwestern Europe, show different behavioural responses from other populations. Additional extensive monitoring of population dynamics and factors such as latitudinal differences, habituation to humans and climate change will help to predict future growth and expansion rates.

Determining the Matrilineal Origin of Indonesian Kerinci Duck Breed (Anas platyrhynchos) Based on MT-ND2 Gene Diversity

The Kerinci duck (Anas platyrhynchos), hailing from Jambi Province, represents one of the local duck breeds of Indonesia. This study aimed to ascertain the matrilineal origin of Kerinci ducks through analysis of the mitochondrial NADH Dehydrogenase subunit 2 (MT-ND2) gene. In this pursuit, forward sequences of the MT-ND2 gene (490 bp) were extracted from unsexed Kerinci ducks, totalling forty-eight (48) sequences, procured from blood samples. The findings demonstrated the identification of fifteen (15) distinct haplotypes within the MT-ND2 gene, with corresponding haplotype diversity (Hd) and nucleotide diversity (pi) values of 0.74 and 0.003, respectively. The resulting phylogenetic tree unveiled that Kerinci ducks exhibit two matrilineal origins: an Asian and an independent Kerinci lineage. Moreover, most Kerinci ducks were categorised within the H4 group (24 birds) of the Asian lineage. Nevertheless, this study also revealed the existence of an independent Kerinci lineage comprising eight (8) duck haplotypes. In conclusion, the analysis of the MT-ND2 gene underscored the genetic introgression of A. zonorhyncha and A. poecilorhyncha in Kerinci ducks.

A new chromosome-scale duck genome shows a major histocompatibility complex with several expanded multigene families

BackgroundThe duck (Anas platyrhynchos) is one of the principal natural hosts of influenza A virus (IAV), harbors almost all subtypes of IAVs and resists to many IAVs which cause extreme virulence in chicken and human. However, the response of duck’s adaptive immune system to IAV infection is poorly characterized due to lack of a detailed gene map of the major histocompatibility complex (MHC).ResultsWe herein reported a chromosome-scale Beijing duck assembly by integrating Nanopore, Bionano, and Hi-C data. This new reference genome SKLA1.0 covers 40 chromosomes, improves the contig N50 of the previous duck assembly with highest contiguity (ZJU1.0) of more than a 5.79-fold, surpasses the chicken and zebra finch references in sequence contiguity and contains a complete genomic map of the MHC. Our 3D MHC genomic map demonstrated that gene family arrangement in this region was primordial; however, families such as AnplMHCI, AnplMHCIIβ, AnplDMB, NKRL (NK cell receptor-like genes) and BTN underwent gene expansion events making this area complex. These gene families are distributed in two TADs and genes sharing the same TAD may work in a co-regulated model.ConclusionsThese observations supported the hypothesis that duck’s adaptive immunity had been optimized with expanded and diversified key immune genes which might help duck to combat influenza virus. This work provided a high-quality Beijing duck genome for biological research and shed light on new strategies for AIV control.

Comparative histological and ultrastructural features of the tongue of the mallard domestic duck, Anas platyrhynchos f. domestica, Anatidae (Linnaeus, 1758) in different two age stages (post-hatching [P2] and adult female) captured from Egypt.

The domestic duck is classified as a specialist filter-feeder bird living in the water. These birds also use grazing and pecking as terrestrial feeding methods. The tongues of domestic ducks, similar to those of other Anseriformes, exhibit numerous types and shapes of mechanical papillae that serve a number of purposes when collecting food. The current study attempts to describe the morphological characteristics of the tongue as well as the mechanical papillae's development. In addition, the study aims to determine whether the papillae observed post-hatching (P2) exhibit similar morphology to those found in adult female avian species, as well as to investigate the readiness of the tongue to fulfill its feeding function following hatching. The comprehensive examination of lingual mucosa is examined about the structural modifications necessary for this variety of feeding activities. In this study, the tongues of nine young (P2) and adult female were used. The tongue had three distinct parts: the apex, which had a lingual nail on its ventral surface; the body, which exhibits numerous small and large conical papillae on its lateral sides and a lingual prominence in the caudal region; and the root, which is covered with numerous conical papillae of varying sizes. Conical, filiform, and hair-like mechanical papillae, the three types of food filtration apparatus, are present in both stages. The intraoral transfer involves several structures, including the median groove, lingual combs, and the rostral border of the lingual prominence. The rostral border of the lingual prominence is characterized by distinct rows of conical papillae. The histological analysis demonstrated the presence of both keratinized and nonkeratinized epithelium on different tongue regions. The lingual salivary glands in the rostral and caudal lingual salivary glands exhibit a pronounced periodic acid-Schiff-positive reaction. Additionally, the yellow adipose tissue and sensory receptors, namely the Grandry and Herbst corpuscles, which collectively form the bill-tongue organ that monitors the movement of food. These results conclude the presence of microstructural species-specific alterations in specific tongue areas of domestic ducks' lingual mucosa. These modifications are formed by the filtering mechanism and terrestrial feeding mechanisms, such as grazing or pecking. Following hatching, the tongue of the domestic duck undergoes significant development, primarily in preparation for grazing activities. The anatomical and histological structure of the young (P2) tongue exhibited similarities to that of the adult female domestic duck while also displaying certain variations that could potentially be attributed to the bird's habitat and mode of feeding. RESEARCH HIGHLIGHTS: The results of this study concluded that the domestic duck exhibit a complex tongue structure characterized by the arrangement and morphology of its mechanical papillae, the presence of the lingual prominence with distinctive shape and the lingual comb. These features are believed to be adaptations that enable the duck to actively and efficiently filter food particles from water, serving as its primary feeding mechanism. Additionally, the tongue of domestic ducks is specifically adapted to facilitate various terrestrial activities, such as grazing and pecking. This adaptation is achieved through the presence of conical papillae and a lingual nail. These investigations facilitate our comprehension of both the anatomical and histological characteristics of the domestic duck tongue, as well as enhance our understanding of bird adaptations to various feeding mechanisms.

The influence of landscape composition and configuration on breeding waterfowl pair abundance in Wisconsin

AbstractHabitat loss and fragmentation have negatively impacted breeding birds across the world. Across guilds, grassland‐dependent birds have experienced the largest proportional loss of their breeding population while wetland‐dependent birds have realized overall net gains in part due to focused conservation efforts. However, some species within the wetland‐dependent guild have a strong dependence on non‐wetland land cover types during the annual cycle and therefore may be equally sensitive to reductions in the composition and altered configuration of upland landcover, such as grasslands. We explored the influence of landcover composition and configuration on the number of breeding pairs of a breeding habitat generalist, the mallard (Anas platyrhynchos), and a grassland‐dependent breeding species, the blue‐winged teal (Spatula discors), in agriculturally‐intensive landscapes of Wisconsin, USA. Because of the extensive landscape alteration and habitat fragmentation that has occurred, we expected mallards to have a more utilitarian response to varying landscape composition compared to a grassland nesting obligate like blue‐winged teal. We used helicopter surveys conducted across 8 years (2001–2003, 2006–2009, and 2012) and remotely‐sensed land cover data to investigate the influence of habitat associations on relative abundance of breeding pairs. Model selection indicated that landscape composition models outperformed landscape configuration and null models for both species. Consistent with our predictions, we found that mallard pair counts were positively influenced by a greater number of land cover covariates compared to blue‐winged teal. Both blue‐winged teal and mallard breeding pairs were positively related to increased composition of emergent and scrub‐shrub wetlands as well as upland grassland. Additionally, we found that mallard pairs were positively related to forested, cattail (Typha sp.), and open water wetland types, whereas predicted blue‐winged teal pair abundance was negatively related to forested wetlands and had a nonlinear relationship and declined when surveyed land sections were comprised of more than 30% cattail‐dominated wetlands and 20% open‐water wetlands. Increased quantities of cattail‐dominated and open‐water wetland cover types comparatively provide less habitat for blue‐winged teal and may reflect broader shifts in habitat composition that have likely resulted from agricultural intensification and stabilized hydrology. Conservation activities that preserve existing nesting land cover types or restore hydrologically‐dynamic emergent wetlands in proximity to upland grassland cover could mutually benefit both species.

Utilizing NMR fecal metabolomics as a novel technique for detecting the physiological effects of food shortages in waterfowl.

Metabolomics is the study of small, endogenous metabolites that participate in metabolic reactions, including responses to stressors. Anthropogenic and environmental changes that alter habitat and food supply can act as stressors in wild waterfowl. These alterations invoke a series of physiological processes to provide energy to restore homeostasis and increase survival. In this study, we utilized fecal metabolomics to measure metabolites and identify pathways related to a 6-day feed restriction in captive mallard ducks (Anas platyrhynchos, n = 9). Fecal samples were collected before (baseline) and during feed restriction (treatment). H1 Nuclear Magnetic Resonance (NMR) spectroscopy was performed to identify metabolites. We found that fecal metabolite profiles could be used to distinguish between the feed-restricted and baseline samples. We identified metabolites related to pathways for energy production and metabolism endpoints, and metabolites indicative of gut microbiota changes. We also demonstrated that mallard ducks could utilize endogenous reserves in times of limited caloric intake. Fecal metabolomics shows promise as a non-invasive novel tool in identifying and characterizing physiological responses associated with stressors in a captive wild bird species.

Incidence and Genetic Investigation of Avian Coronaviruses in Migratory Ducks From South Korea

Coronaviruses (CoVs) belonging to the Gamma-CoV and Delta-CoV genera are widespread in poultry and wildfowl. Migratory birds, particularly duck species, serve as hosts for CoVs and play a pivotal role in transmitting the viruses to other species, including mammals. Despite the potential risks to animals and humans, there remains a narrow knowledge of the genetic and epidemiological properties of CoVs in wild birds. The current research aimed to detect and characterize CoVs present in migratory duck species (Anas acuta, Anas platyrhynchos, and Anas poecilorhyncha) from South Korea. Employing two rounds of pan‐CoV real‐time reverse transcription‐polymerase chain reaction (RT‐PCR) and nested PCR (nPCR) assays amplifying the conserved RNA‐dependent RNA polymerase (RdRp) portion common to all known CoVs, we screened 2120 duck fecal samples collected during 2022–2023. The results indicated the presence of CoVs in 4.2% (91/2120) of samples from migratory ducks. Nucleotide sequencing of the RdRp gene revealed that all identified CoVs were clustered within the Gamma-CoV genus. Further phylogenetic analysis suggested that South Korean gamma‐CoVs belong to the Igacovirus subgenus and share similarities with those found worldwide, highlighting the critical role of migratory ducks in introducing and exporting avian CoVs. We discovered two clade VII igacovirus strains in wild ducks closely related to those in pigeons, implying potential cross infection between these avian species. Overall, our study underscores the importance of active surveillance and monitoring of avian CoVs in wild birds as a preemptive response against the forthcoming emergence of new CoV species that can threaten both animal and human health.

Parasites as Indicators of Biotic Interrelations between Fishes and Waterbirds

The paper deals with the structural features of the waterbirds' cenoses, the fish population composition and distribution of metacercariae of trematodes, whose final hosts are waterbirds, in the model shallow lentic ecosystems of the city of Kyiv (Almazne, Martyshev, Verbne lakes and Sovski ponds). The waterbird cenosis was dominated by ichthyophagous (58.5-75.7%) and pantophagous birds (16.4-41.42%). The black-headed gull <i>Chroicocephalus ridibundus</i> (21.9-56.7%) prevailed in terms of relative abundance everywhere. The ornithocenoses differed in terms of the subdominant species: in the Almazne lake it was <i>Podiceps cristatus</i>, in the Martyshev Lake - <i>Sterna hirundo </i>(14.6%), in the Sovski ponds and Verbne Lake - <i>Anas platyrhynchos</i> (12.8-20.2%). Differences in the coastal ornithocenoses' composition were confirmed by results of the cluster analysis WPGMA (weighted pair-group centroid (median)); distance measure - 1-Pearson <i>r</i>). The coastal fish population comprised 24 species, including the native fresh-water (15 species), Ponto-Caspian and Mediterranean self-dispersers (4 species), and alien species - distant invaders (5 species). Parasitological studies revealed trematode metacercariae localized in lens (<i>Diplostomum</i> sp.) and vitreous body (<i>Tylodelphys clavata</i>) of the eye, ripples (<i>Apatemon gracilis</i>), and in the integument of the body (<i>Posthodiplostomum cuticola</i>). The discriminant analysis enabled to reveal significant differences in the species composition and abundance of trematode metacercariae in the water bodies with different structure of the water ornithocenoses (Wilks' Lambda: approx. 0.92235; <i>F</i>(8, 510) = 2.6293f) - 2.6293; the dispersion analysis showed confidently lower total number of trematode metacercariae in the Almazne Lake (Wilks' Lambda = 0.87377; <i>F</i>(6, 432) = 5.0253; <i>p</i><0.00005).

Species composition of Home gardens and Food security in Maluku, Kinshasa

This study aimed to assess the species composition of home gardens and their contribution to farmers' food security. Through a questionnaire-based survey in Maluku, Kinshasa, it was determined that the primary use of home garden products is household consumption. Most respondents indicated that home gardens significantly contribute to the households' food security. The chi-square test result indicated that only the livestock variable was statistically significant. The species composition presented a diversity of species that we categorized into three components: crops, trees, and livestock. The most commonly cropped species are Manihot glaziovii, Ipomoea batata, Saccharum officinarum, and various species with the Musa genus. The most planted are Manguifera indica, Persea americana, and Elaeis guineensis. Regarding livestock, the most reared are Gallus gallus and Anas platyrhynchos. The choice of these particular species depicts the diet and cultural values of farmers. The study shows the critical role of home gardens in supporting households’ food security, hence combating hunger and malnutrition using a sustainable agricultural practice.

Metabarcoding reveals waterbird diet in a French Ramsar wetland: implications for ecosystem management

Environmental and/or climate changes, occurring at a global or local scale, can significantly impact the diets, health, and population dynamics of waterbirds. This study aimed to develop an effective tool, using DNA metabarcoding of fecal samples, for monitoring waterbird diets during the breeding season in a Ramsar freshwater wetland in Northern France. We collected bird feces across eight marshes with varying anthropic usage. The majority of samples (69%) were from five waterbird species: Eurasian coot (Fulica atra), Eurasian moorhen (Gallinula chloropus), mallard (Anas platyrhynchos), mute swan (Cygnus olor), and grey heron (Ardea cinerea). DNA was extracted from 116 samples, with plant and invertebrate primers used to undertake multi-marker metabarcoding. Despite a negative impact of uric acid on DNA amplification, we observed significant dietary variations among bird species and sampling sites. Wetland bird diets primarily consisted of four arthropod families, dominated by Chironomidae and Asellidae. The number of plant families detected was higher, consisting of 33 families, with Poaceae highly prevalent within wetland bird diets. This study shows that using DNA metabarcoding to explore interactions between waterbirds and trophic resources is a promising approach to assist wetland management and assess the effect of environmental changes.

Growth Performance, Serum Chemistry, Cellular Immunity, and Carcass Traits of American Pekin Ducks (Anas Platyrhynchos) Reared Under Different Production Systems

Growth Performance, Serum Chemistry, Cellular Immunity, and Carcass Traits of American Pekin Ducks (Anas Platyrhynchos) Reared Under Different Production Systems

Changes in the adult sex ratio of six duck species breeding populations over two decades

Despite all efforts, long-term changes in the adult sex ratios of breeding duck populations are still unclear; this uncertainty is especially true for male-bias populations, which are often under the scrutiny of researchers lacking convenient results for the active protection of endangered species. Species with male-bias populations are usually strongly affected by a decline in population size that leads to a higher extinction risk. In this study, we examined our long-term data of the abundance of breeding populations in six duck species (Mallard Anas platyrhynchos, Gadwall Mareca strepera, Red-crested Pochard Netta rufina, Common Pochard Aythya ferina, Tufted Duck Aythya fuligula, and Common Goldeneye Bucephala clangula) from fishponds in South Bohemia, Czechia, between 2004 and 2022. This evidence was used to assess long-term changes in the adult sex ratio in these breeding populations and investigate the possible effects of the NAO index (North Atlantic Oscillation index) on them, indicating climate conditions in winter. We determined a long-term decrease of the proportion of females in the breeding season in two of the six examined species: Common Pochard and Red-crested Pochard, which is driven by the long-term increase in the number of males in contrast to the decreasing or stable number of females likely caused by different migration behaviours between females and males. In the case of Common Pochard, in breeding populations, we estimated 60–65% of males in the early 2000s rising to 75–80% in the early 2020s. However, we establish no significant effects linked to climate conditions of the previous winter in these species as a crucial cause of the changes of the proportion of females in the breeding population.

West Nile Virus Infection in a Pekin Duck ( Anas platyrhynchos domesticus ) Developer Flock.

Developer ducks are ducks being reared for breeding. Like breeder candidate chickens, they are raised with appropriate light and feed programs. A commercial Pekin duck (Anas platyrhynchos domesticus) developer flock experienced an extraordinary, elevated mortality event at 6 wk of age. Weekly mortality rate that week was 162 ducklings out of a flock of 6420 (2.5%). Mortality jumped to 988 (15.4%) ducklings the next week. On first elevated mortality, six dead ducks from that flock were submitted for diagnostic investigation at Michigan State University Veterinary Diagnostic Laboratory. Myocarditis, pale striping or diffuse pallor of the epicardium, was grossly evident in five of the six submitted ducklings. All of the ducklings had hydropericardium, three had ascites, and three had congested meninges. Histology confirmed myocarditis with myocardial necrosis. Cerebrum and brainstem had lymphocytic vasculitis with rare neuronal necrosis in affected areas, as well as Purkinje cells in the cerebellum. West Nile virus was confirmed by PCR the day after submittal and by immunohistochemistry soon thereafter.