Articoli di riviste: "Mallard"

1

Gillespie, Grant D. "Hybridization, Introgression, and Morphometric Differentiation between Mallard (Anas platyrhynchos) and Grey Duck (Anas superciliosa) in Otago, New Zealand". Auk 102, n. 3 (1 luglio 1985): 459–69. http://dx.doi.org/10.1093/auk/102.3.459.

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Abstract Small numbers of Mallard (Anas platyrhynchos) were introduced into New Zealand from Great Britain and North America over 100 years ago. Both sexes have undergone differentiation in size and plumage characters as a consequence of hybridization with the indigenous Grey Duck (A. superciliosa). Pure forms of both species, as documented by early descriptions, appear to be disappearing, particularly the Grey Duck. In Otago, the Mallard and Grey Duck are introgressively hybridizing, and the majority of intergrades are Mallard-like in appearance. Separation of Mallards, hybrid birds, and Grey Ducks was achieved using a stepwise cluster analysis of mensural characters. The observed morphometric differentiation was not continuous throughout the Otago population, and a total of 5 discontinuities (groups of morphologically similar birds) were distinguished: male Mallards, female Mallards, Grey Ducks, and 2 groups of hybrid birds. The use of bivariate scattergrams of skull length and eye-lens weight provided the most useful illustration of the distinctions among Mallard, hybrid, and Grey Duck populations. As a consequence of hybridization, two morphologically distinct hybrid populations have been produced: one resembles the Grey Duck and the other the Mallard. This situation is discussed in relation to the two hybrid forms of the Marianas Mallard (A. oustaleti). The Mallard was so successful in newly created agricultural habitat that by 1958 this species constituted 53% of the Mallard-Grey Duck population. Prior to 1958 the observed hybrid frequency was less than 3% and the reduction in the proportion of the Grey Duck most probably was the result of habitat reduction. In 1977 the Mallard comprised 82% of the Mallard-Grey Duck population, and there was concern over the number of pure Grey Ducks remaining in Otago. By 1981-1982 levels of hybridization, based on plumage analysis, had reached 51%, and the proportion of pure Grey Ducks had dropped to 4.5%, which is below the level suggested for the maintenance of a species. In the absence of reproductive isolation or antihybridization mechanisms between these two species, the Mallard and hybrid populations represent a potential threat to the conservation of the New Zealand Grey Duck.

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Schummer, Michael L., John Simpson, Brendan Shirkey, Samuel R. Kucia, Philip Lavretsky e Douglas C. Tozer. "Population genetics and geographic origins of mallards harvested in northwestern Ohio". PLOS ONE 18, n. 3 (15 marzo 2023): e0282874. http://dx.doi.org/10.1371/journal.pone.0282874.

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The genetic composition of mallards in eastern North America has been changed by release of domestically-raised, game-farm mallards to supplement wild populations for hunting. We sampled 296 hatch-year mallards harvested in northwestern Ohio, October–December 2019. The aim was to determine their genetic ancestry and geographic origin to understand the geographic extent of game-farm mallard introgression into wild populations in more westward regions of North America. We used molecular analysis to detect that 35% of samples were pure wild mallard, 12% were early generation hybrids between wild and game-farm mallards (i.e., F1–F3), and the remaining 53% of samples were assigned as part of a hybrid swarm. Percentage of individuals in our study with some form of hybridization with game-farm mallard (65%) was greater than previously detected farther south in the mid-continent (~4%), but less than the Atlantic coast of North America (~ 92%). Stable isotope analysis using δ2Hf suggested that pure wild mallards originated from areas farther north and west than hybrid mallards. More specifically, 17% of all Ohio samples had δ2Hf consistent with more western origins in the prairies, parkland, or boreal regions of the mid-continent of North America, with 55%, 35%, and 10% of these being genetically wild, hybrid swarm, and F3, respectively. We conclude that continued game-farm introgression into wild mallards is not isolated to the eastern population of mallards in North America, and may be increasing and more widespread than previously detected. Mallards in our study had greater incidence of game-farm hybridization than other locales in the mid-continent but less than eastern North American regions suggesting further need to understand game-farm mallard genetic variation and movement across the continent.

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3

Samsonov, E. V., S. G. Shikhranov e A. M. Samsonova. "JUSTIFICATION OF THE TIMING OF THE OPENING OF SUMMER-AUTUMN AMATEUR AND SPORTS HUNTING FOR WATERFOWL IN THE NORTH OF THE LOWER VOLGA". Scientific Life 16, n. 7 (2021): 945–59. http://dx.doi.org/10.35679/1991-9476-2021-16-7-945-959.

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In accordance with Russian legislation, the timing of hunting for game birds can be adjusted at the regional level. Biological justification can be crucial in determining the timing of the hunt, namely the timing of the start and end of the hunting season. Based on the registration of waterfowl, a biological justification for the timing of the opening of hunting in the summer-autumn and autumn-winter seasons is given. The studies were carried out in the Saratov region in the water area of the Volga River (Volgograd reservoir). A total of 7 surveys were carried out, the total length of the survey routes was 100.6 km. The dominant species in the brood period is the mallard. Shares of recorded birds: mallard (Anas platyrhynchos L, 1758) - 96.6%, coot (Fulica atra L, 1758) - 2.5%, teal-cattle (Anas querquedula L, 1758) - 0.9%. The beginning of the mallard incubation period in 2020 is the first decade of May. The period of mass incubation of masonry by mallards is from the third decade of May to the second decade of June. The first mallard chicks appeared in the third decade of May. From the second decade of June to the second decade of July - the period of mass appearance of mallard chicks. The proportion of non-flying young mallards in the second decade of August was 33.3%, in the third decade of August - 28.3%. The end of the period of mass rise of young mallards "on the wing" took place in the first ten days of September, the proportion of non-flying young mallards in this period amounted to 4.3%. The increase in the number of mallards in the second and third ten days of July amounted to 142.0%. The beginning of the migratory summer-autumn period of 2020 (for species that do not tend to nest in the study area) fell on the first ten days of September. Biologically substantiated period for the opening of hunting in the summer-autumn and autumn-winter season is the first ten days of September (the share of non-flying young animals is less than 10%).

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4

Green, Andy J. "Comparative feeding behaviour and niche organization in a Mediterranean duck community". Canadian Journal of Zoology 76, n. 3 (1 marzo 1998): 500–507. http://dx.doi.org/10.1139/z97-221.

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Feeding behaviour of the Marbled Teal, Marmaronetta angustirostris, Mallard, Anas platyrhynchos, Garganey, Anas querquedula, and Ferruginous Duck, Aythya nyroca, in the Göksu Delta, Turkey, was compared from 10 July to 6 August 1995. Almost all individuals observed were postbreeding adults and juveniles. Marbled Teal fed closest to the surface (mean depth within the water column 8.4 cm), chiefly by bill dipping (66%) and gleaning (14%). Garganey fed at a mean depth of 9.1 cm, mainly by bill dipping (57%) and neck dipping (35%). Mallards fed at greater depths (mean 31.8 cm), mainly by upending (tipping 46%) and neck dipping (41%). Ferruginous Ducks fed at the greatest depths (mean 38.4 cm), chiefly by diving (76%). Marbled Teal moved most frequently between feeding events and Mallards moved least frequently. As in previous studies of dabbling ducks, the largest species (Mallard) upended more and fed deeper in the water column. However, Mallards used shallower microhabitats than smaller dabbling ducks. Dabbling and diving duck guilds were not discernible in either horizontal (feeding habitat) or vertical (feeding behaviour) niche dimensions, and the Mallard and Ferruginous Duck were related in both dimensions. Niche overlaps between species pairs along the two dimensions were negatively correlated (r = -0.71, P = 0.12), supporting niche complementarity.

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5

Ankney, C. Davison, Darrell G. Dennis, Lisa N. Wishard e James E. Seeb. "Low Genic Variation between Black Ducks and Mallards". Auk 103, n. 4 (1 ottobre 1986): 701–9. http://dx.doi.org/10.1093/auk/103.4.701.

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Abstract We used allozyme electrophoresis to estimate the degree of genetic differentiation among allopatric and sympatric populations of American Black Ducks (Anas rubripes) and Mallards (A. platyrhynchos). Mallards were collected in California, Saskatchewan, Manitoba, and Ontario, and Black Ducks were collected in Newfoundland, Nova Scotia, and Ontario. The mean genetic distances, D̄, between Black Duck populations (0.0007), between Mallard populations (0.0010), and between Mallard and Black Duck populations (0.0006) were virtually identical; there was as much genetic differentiation within the two species as there was between them. Such small genetic distances are characteristic of local populations of avian species in other orders, and are consistent with what is known about the lack of reproductive isolation between Black Ducks and Mallards. Although the two taxa are still somewhat split on an east-west basis, our genetic data do not support even subspecific status for the Black Duck.

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6

Han, Dianlei, Hairui Liu, Zhiqian Tong, Jiahang Pan e Xinzhong Wang. "Effects of the speed on the webbed foot kinematics of mallard (Anas platyrhynchos)". PeerJ 11 (15 maggio 2023): e15362. http://dx.doi.org/10.7717/peerj.15362.

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In this study, the effect of the speed on the webbed foot locomotion of the mallard was analyzed based on a considerable number of reliable indoor test data. Four adult male mallards were selected for analysis, and the locomotion speed of the mallard was controlled using the treadmill at an accurate and adjustable speed. The locomotion pattern of the webbed foot of the mallard at different speeds was recorded using a high-speed camera. The changes in the position and conformation of the webbed foot during locomotion on a treadmill were tracked and analyzed using Simi-Motion kinematics software. The results indicated that the stride length of the mallard increased, and the stance phase duration was shortened with the increase of the speed, whereas the swing phase duration did not vary significantly. The duty factor decreased with the increase of the mallard speed but not drop below to 0.5, because the mallards flew with their wings, or moved backward relative to the treadmill with the further increase of the speed. Using the energy method to further distinguish gait, and through the percentage of congruity analysis, it was found that between 0.73 and 0.93 m/s, the gait experienced a transition from walking to grounded running, with no significant changes in spatiotemporal parameters. At speeds between 0.93 and 1.6 m/s, mallards adopt a grounded running gait. The instantaneous changes of the tarsometatarso-phalangeal joint (TMTPJ) angle and the intertarsal joint (ITJ) angle at touch-down, mid-stance and lift-off concomitant with the change of the speed were examined with the TMTPJ and ITJ angle as the research objects. Moreover, the continuous changes of the joint angles were examined in a complete stride cycle. The result indicated that the increase of the speed will also make the TMTPJ and ITJ angle change ahead of time in a stride cycle, proving the shortened stance phase duration. The ITJ angle changed much more than the TMTPJ. Thus, the above result reveals that the mallard primarily responds with the increase of the speed by adjusting the ITJ, instead of the TMTPJ. The vertical displacement of the toe joint points and the toe joint angle was studied (α joint angle is between the second toe and the third toe; β joint angle is between the third toe and the fourth toe) with a complete stride cycle as the research object. The distal phalanxes of the second, third and fourth toes first contacted the ground, and the proximal phalanx touched the ground in turn during the early stance phase duration of the mallard, as indicated by the result of this study. However, the toes got off the ground in turn from the proximal phalanxes when the mallard foot got off the ground. With the decrease of the interphalangeal α and β joint angles, the foot web tended to be close and rapidly recovered before the next touch-down. The above result reveals that the webbed foot of the mallard is a coupling system that plays a role in the adjustment of speed.

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7

Pushkova, Alina E., e Ekaterina Yu Mosolova. "Urban mallard population (Anas platyrhynchos) in Saratov: Wintering, nesting, degree of synanthropization". Izvestiya of Saratov University. Chemistry. Biology. Ecology 23, n. 4 (18 dicembre 2023): 479–90. http://dx.doi.org/10.18500/1816-9775-2023-23-4-479-490.

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The article reflects data on year-round studies of the urban mallard population in Saratov, allowing the assessment of the condition and the study of the factors influencing its formation. An estimate of the mallard population in the winter periods of 2020–2023 is presented. It is shown that the number negatively correlates with frosts and precipitation, and there is a statistically significant positive relationship between the number of people feeding ducks and the number of mallards. The state of the wintering and nesting population is assessed according to the index of synanthropization, the rate and path of penetration of the species into urbanized landscapes, and the stage of formation of the urban population in Saratov is determined. Adaptations of mallards to life in urban conditions and their impact on the ecology of the species as a whole are highlighted. The article emphasizes the need for further research on the impact of urbanization on mallard ecology and the benefits of this species for the urban ecosystem. The importance of monitoring population dynamics for its adaptation to the urban environment and maintaining the stability of the entire population is noted. In addition, the article provides a basis for further studies of the urban mallard population and can be a valuable source of information for the development of local programs for managing the available resources of ducks living in the park area of the city.

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8

Evseev, Danyel, e Katharine Magor. "Innate Immune Responses to Avian Influenza Viruses in Ducks and Chickens". Veterinary Sciences 6, n. 1 (10 gennaio 2019): 5. http://dx.doi.org/10.3390/vetsci6010005.

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Mallard ducks are important natural hosts of low pathogenic avian influenza (LPAI) viruses and many strains circulate in this reservoir and cause little harm. Some strains can be transmitted to other hosts, including chickens, and cause respiratory and systemic disease. Rarely, these highly pathogenic avian influenza (HPAI) viruses cause disease in mallards, while chickens are highly susceptible. The long co-evolution of mallard ducks with influenza viruses has undoubtedly fine-tuned many immunological host–pathogen interactions to confer resistance to disease, which are poorly understood. Here, we compare innate responses to different avian influenza viruses in ducks and chickens to reveal differences that point to potential mechanisms of disease resistance. Mallard ducks are permissive to LPAI replication in their intestinal tissues without overtly compromising their fitness. In contrast, the mallard response to HPAI infection reflects an immediate and robust induction of type I interferon and antiviral interferon stimulated genes, highlighting the importance of the RIG-I pathway. Ducks also appear to limit the duration of the response, particularly of pro-inflammatory cytokine expression. Chickens lack RIG-I, and some modulators of the signaling pathway and may be compromised in initiating an early interferon response, allowing more viral replication and consequent damage. We review current knowledge about innate response mediators to influenza infection in mallard ducks compared to chickens to gain insight into protective immune responses, and open questions for future research.

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9

Bordjan, Dejan. "The Mallard Anas platyrhynchos in Slovenia: a review with an estimation of its current population". Acrocephalus 41, n. 186-187 (1 dicembre 2020): 69–118. http://dx.doi.org/10.2478/acro-2020-0006.

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Abstract Although the Mallard is one of the most numerous and best-studied waterbirds in the world, it received almost no attention in Slovenia. It is one of the most frequently observed waterbirds in our country, with frequency often reaching 100%. Sites with lower frequency either freeze in winter or have a low number of individuals to start with. The Mallard is also the most dominant species (17.5% and 89.0%) with higher dominance at sites less suitable for waterbirds due to the lack of available shoals. Mallards reach their maximum numbers during fall migration and winter. Spring migration has no discernible peak and has been significant only for Lake Cerknica. On shallow waters, the maximum is reached in August and September, a month before fall migration begins, indicating local movement to food-rich sites. Females make up only 36.7% of the observed Mallards and reach the maximum proportion (41.5%) in winter and the lowest in April and May (14.7%), when they nest. The breeding season in Slovenia lasts from mid-January to early December, with the majority of females rearing broods from April to July. Average brood size is 6.2 ± 2.66 and declines with season, age of young and altitude. It varies between habitat types and is highest on Treatment and Coastal Wetlands (7.3) and lowest on deep waters such as Reservoirs (5.7) and Lakes (5.6). No really high breeding densities were found in Slovenia and were similar to those in other countries. Breeding densities are higher on smaller Ponds (< 8 ha), on sites with isolated islands and breeding colonies of gulls and terns (e.g. Lake Ptuj). Breeding density also decreases with elevation. Slovenian breeding population is estimated at 1,473–3,763 bp and wintering population averages 22,237 (10,376–32,010) individuals. Data suggest a decline in the wintering population most likely due to warmer winters. The majority of Mallards winter in NE Slovenia, where eight of eleven sites have a maximum of more than 1,000 Mallards. Most Mallards winter on the Drava river with Ptuj and Ormož lakes, where the highest numbers of Mallards were also recorded (Lake Ptuj: 8,330 ind., Lake Ormož: 5,400 ind.). The highest number of individuals during spring migration was recorded on Lake Cerknica (4,581) and during autumn migration on Medvedce reservoir (3,379). Apart from standing waters, the highest density of wintering Mallards is found in urban sections of slow-flowing rivers, probably due to higher safety and food availability.72,731 Mallards were hunted between 2001 and 2018, mainly in NE Slovenia (28% in the Pomursko hunting management district). The number of Mallards hunted is declining in all hunting areas and has declined by 64% since 2001 and even more since the 1990s. According to hunt data, hunting is by far the most important cause of the Mallard mortality in Slovenia (97.4%), followed by predation (1.1%). The Mallard mortality in Slovenia is largely unstudied and natural mortality is most likely underestimated, not only because it does not include mortality in the pre-fledging period, a period with the lowest survival, but also because the detectability of natural mortality is considerably lower. In contrast to the hunted numbers, there have been only nine recoveries of ringed individuals from abroad in the last 100 years, suggesting that hunters may not be reporting recoveries to the ringing centre. Apart from the 1972–1975 period, when 87% of Mallards were ringed, the intensity of ringing of Mallards in Slovenia is low, resulting in only seven Mallards recovered abroad. The longest distance of a Mallard ringed in Slovenia comes from Ukraine (1,290 km), while the longest distance between ringing and recovery sites is 2,075 km from an individual ringed in Finland. The only colour morphs documented in Slovenia are Mallards with paler feathers, attributed to one of the colour aberrations resulting from lower melanin productivity. Only few hybrids and mixed pairings with other wild duck species were observed.

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10

Yetter, Aaron P., Joshua D. Stafford, Christopher S. Hine, Matthew W. Bowyer, Stephen P. Havera e Michelle M. Horath. "Nesting Biology of Mallards in West-central Illinois". Illinois Natural History Survey Bulletin 39, n. 1-6 (30 settembre 2009): 1–38. http://dx.doi.org/10.21900/j.inhs.v39.95.

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The number of Mallards (Anas platyrhynchos) breeding in Illinois and eastern North America has increased in recent decades; however, few studies have investigated the nesting biology of Mallards outside primary production areas. Therefore, we radiomarked resident female Mallards (n = 148) in west-central Illinois during 1998–2003 to assess nesting parameters and evaluate recruitment. Mean initiation date for first nests ranged from 22 April to 6 May, and the majority (75%) of nests were initiated by 20 May. Therefore, the majority of nests were predicted to hatch by 24 June. The nesting season averaged 88 days (range: 77–103 days). The proportion of unsuccessful females that renested ranged from 50.0–85.7%, and adults were more likely to renest (75.0%) than yearlings (48.0%). Nest success ranged from 9.8–33.3% and was 19.6% overall; hen success was 28.3%. Initial brood size was 8.2 ± 0.3 ducklings, but brood size declined to 3.0 ± 0.6 ducklings by 17 days posthatch. Brood survival to 20 days was 0.759 ± 0.081, and 20-day duckling survival was 0.413 ± 0.035. Female survival during spring-summer ranged from 0.546–1.00 and averaged 0.710 ± 0.096. Likewise, estimated Mallard recruitment varied annually (range: 0.302–0.672 female ducklings/female). Assuming constant female and duckling survival, we estimated that a recruitment rate of 0.613 female ducklings/adult female was necessary to maintain a stable Mallard breeding population in west-central Illinois. Estimated Mallard reproduction and recruitment was similar to that observed in other areas of North America. Nest success and hen success approached or exceeded estimated thresholds for population stability in most years; however, hen success averaged over the study period was insufficient for local population maintenance and growth. Female survival was comparable to that observed in other studies but may have limited population growth in some years. Duckling survival was sufficient for population maintenance. Management designed to enhance hen success and brood habitat may augment Mallard recruitment in west-central Illinois.

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Wells-Berlin, Alicia M., Harold H. Prince e Todd W. Arnold. "Incubation Length of Dabbling Ducks". Condor 107, n. 4 (1 novembre 2005): 926–29. http://dx.doi.org/10.1093/condor/107.4.926.

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AbstractWe collected unincubated eggs from wild Mallard (Anas platyrhynchos), Gadwall (A. strepera), Blue-winged Teal (A. discors), and Northern Shoveler (A. clypeata) nests and artificially incubated them at 37.5°C. Average incubation lengths of Mallard, Gadwall, and Northern Shoveler eggs did not differ from their wild-nesting counterparts, but artificially incubated Blue-winged Teal eggs required an additional 1.7 days to hatch, suggesting that wild-nesting teal incubated more effectively. A small sample of Mallard, Gadwall, and Northern Shoveler eggs artificially incubated at 38.3°C hatched 1 day sooner, indicating that incubation temperature affected incubation length. Mean incubation length of Blue-winged Teal declined by 1 day for each 11-day delay in nesting, but we found no such seasonal decline among Mallards, Gadwalls, or Northern Shovelers. There is no obvious explanation for the seasonal reduction in incubation length for Blue-winged Teal eggs incubated in a constant environment, and the phenomenon deserves further study.

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12

D'Eon, Robert G., Norman R. Seymour e Arnold H. Boer. "Black duck – mallard behavioural interactions in relation to hybridization". Canadian Journal of Zoology 72, n. 8 (1 agosto 1994): 1517–21. http://dx.doi.org/10.1139/z94-200.

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Black duck (Anas rubripes) numbers have declined over the past several decades in conjunction with a gradual eastward range expansion of the mallard (Anas platyrhynchos). Introgressive hybridization has been proposed as a principal cause of this decline. We studied a sympatric population of black ducks and mallards to determine the relative contribution of forced copulation and mixed pairs to hybrid production and test the common belief that mallards are more aggressive than black ducks. Mixed pairs (14% of all pairs), not interspecific forced copulation, likely accounted for the 2% hybridization rate on the study area. Sexual and hostile aggression was greater among mallards than black ducks prior to the establishment of territories, but thereafter was similar between the two species.

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Hanson, Alan R., C. Davison Ankney e Darrell G. Dennis. "Body weight and lipid reserves of American Black Ducks and Mallards during autumn". Canadian Journal of Zoology 68, n. 10 (1 ottobre 1990): 2098–104. http://dx.doi.org/10.1139/z90-292.

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A comparison of body weight and lipid reserves (weights of mesenteric and abdominal fat) of American Black Ducks (Anas rubripes) and Mallards (Anas platyrhynchos) during autumn was done to provide insight regarding the recent contemporaneous decline in Black Duck and increase in Mallard populations of eastern North America. Data were collected on 350 Black Ducks and 1477 Mallards shot by hunters in southwestern Ontario from September 24 to December 20, 1986. Date shot and fresh body weight were recorded, and the head, a wing, a foot, and the viscera were removed and frozen. Body weight and lipid deposits (weight of mesenteric and abdominal fat) were compared between the two species. The first principal component from an analysis of nine morphometric measurements was used as a covariate in subsequent analysis to remove variation in body weight and lipid deposits caused by differences in structural size. Although all age-sex classes of Mallards and Black Ducks stored lipids during the autumn, adult male and juvenile female Black Ducks stored less lipids than did their Mallard counterparts (P ≤ 0.01). Differences in lipid reserves during fall migration may be a proximal reason for the lower survival of adult male and juvenile Black Ducks compared with Mallards and may also influence the timing of intraspecific, and the rate of interspecifc, pair formation.

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Bengtsson, Daniel, Kamran Safi, Alexis Avril, Wolfgang Fiedler, Martin Wikelski, Gunnar Gunnarsson, Johan Elmberg, Conny Tolf, Björn Olsen e Jonas Waldenström. "Does influenza A virus infection affect movement behaviour during stopover in its wild reservoir host?" Royal Society Open Science 3, n. 2 (febbraio 2016): 150633. http://dx.doi.org/10.1098/rsos.150633.

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The last decade has seen a surge in research on avian influenza A viruses (IAVs), in part fuelled by the emergence, spread and potential zoonotic importance of highly pathogenic virus subtypes. The mallard ( Anas platyrhynchos ) is the most numerous and widespread dabbling duck in the world, and one of the most important natural hosts for studying IAV transmission dynamics. In order to predict the likelihood of IAV transmission between individual ducks and to other hosts, as well as between geographical regions, it is important to understand how IAV infection affects the host. In this study, we analysed the movements of 40 mallards equipped with GPS transmitters and three-dimensional accelerometers, of which 20 were naturally infected with low pathogenic avian influenza virus (LPAIV), at a major stopover site in the Northwest European flyway. Movements differed substantially between day and night, as well as between mallards returning to the capture site and those feeding in natural habitats. However, movement patterns did not differ between LPAIV infected and uninfected birds. Hence, LPAIV infection probably does not affect mallard movements during stopover, with high possibility of virus spread along the migration route as a consequence.

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Bombik, Elżbieta, Katarzyna Pietrzkiewicz e Antoni Bombik. "Analysis of the Fatty Acid Profile of the Tissues of Hunted Mallard Ducks (Anas platyrhynchos L.) from Poland". Animals 12, n. 18 (13 settembre 2022): 2394. http://dx.doi.org/10.3390/ani12182394.

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The aim of the study was to analyse the fatty acid profile of selected tissues of mallard ducks (Anas platyrhynchos L.), in relation to where they were obtained and their sex, with regard to the human diet. The study was carried out on material obtained from mallard ducks from two study areas: the Siedlce hunting district and the Leszno hunting district. The research material was the breast and leg muscles of 28 mallards. The samples were frozen and stored at −20 °C. The fatty acid profiles in the biological samples were determined by selected ion recording (SIR). The results showed significantly (p < 0.05) lower average levels of saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) and significantly higher (p < 0.05) average levels of polyunsaturated fatty acids (PUFAs), n-6 PUFAs, and n-3 PUFAs in the breast muscles of the mallards obtained in the Siedlce hunting district. This in conjunction with the higher (p < 0.05) hypocholesterolaemic/hypercholesterolaemic index (h/H) in the leg muscles and lower (p < 0.05) atherogenic and thrombogenic indices (AI and TI) in the leg and breast muscles of mallards in the Siedlce hunting district indicate the higher health-promoting value of the meat of ducks from this region. The average n-6/n-3 PUFA ratio in the breast muscles was significantly (p < 0.05) higher in mallards obtained in the Leszno hunting district. Males of the species had a significantly (p < 0.05) higher average n-6/n-3 PUFA ratio in the breast muscles than females. The PUFA/SFA ratio was significantly (p < 0.05) higher in the leg muscles of the female mallards than in the males.

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Tidwell, Paul R., Elisabeth B. Webb, Mark P. Vrtiska e Andrew A. Bishop. "Diets and Food Selection of Female Mallards and Blue-Winged Teal During Spring Migration". Journal of Fish and Wildlife Management 4, n. 1 (1 giugno 2013): 63–74. http://dx.doi.org/10.3996/072012-jfwm-062.

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Abstract Waterfowl nutritional requirements and food availability at migration stopover habitats may differ from those at nesting or wintering areas. Although there is little information on factors that influence waterfowl diets and food selection during migration, we hypothesized that bird age and wetland density in the surrounding landscape would influence food selection. Thus, the objective of this study was to quantify mallard Anas platyrhynchos and blue-winged teal Anas discors diets during migration and evaluate effects of age and wetland density on waterfowl food selection. We collected 30 mallards and 29 blue-winged teal with food items present in esophagi from wetlands in south-central Nebraska during spring 2008 and 2009. Smartweed Polygonum spp. and barnyard grass Echinochloa spp. were the most common seeds found in both mallards and blue-winged teal, while Naididae and Chironomidae larvae were the most common invertebrates in mallard and blue-winged teal diets, respectively. Invertebrates were consumed by both species in greater proportion than available. Both mallards and blue-winged teal collected in wetland complexes selected some seeds over others, whereas birds in isolated wetlands foraged on foods in proportion to availability. After-hatch-year mallards also selected for some seeds over others, as compared with hatch-year birds, which foraged opportunistically on available foods. If after-hatch-year birds and birds in wetland complexes are able to be more selective in their diets relative to food availability at individual wetlands, they may be able to acquire and replenish lipids reserves more efficiently than hatch-year birds or birds in areas with lower wetland densities.

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17

Bombik, Elżbieta, Antoni Bombik e Katarzyna Pietrzkiewicz. "Analysis of Zinc and Copper Content in Selected Tissues and Organs of Wild Mallard Ducks (Anas platyrhynchos L.) in Poland". Animals 14, n. 8 (14 aprile 2024): 1176. http://dx.doi.org/10.3390/ani14081176.

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Abstract (sommario):

The research material included selected muscles and liver of mallard ducks obtained in two research areas. A total of 28 mallards were obtained for the study—six males and six females from the Siedlce hunting district and eight males and eight females from the Leszno hunting district. Zinc and copper concentrations were determined by inductively coupled plasma optical emission spectrometry (ICP OES). It was concluded from the study that the Leszno hunting district is more polluted than the Siedlce hunting district. Among the examined tissues of mallard ducks from both hunting districts, the highest content of zinc and copper was found in the liver. In this organ, birds shot in the Leszno hunting district were characterized by a significantly higher content of these elements compared to birds shot in the Siedlce hunting area. The significantly higher average zinc and copper concentrations in the liver of mallards harvested in this hunting district may have been influenced by fertilization of crop fields in this area with fertilizers containing these elements and by extraction of ore containing zinc and copper minerals in the Legnica-Głogów Copper District. This is an important problem with regard to the safety of consumers of game meat. It was shown that the tissues of male mallards were characterized by higher average levels of zinc and copper than those of females, but the differences were statistically significant only in the case of the average copper content in the leg muscles.

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18

Boyer, Ryan A., John M. Coluccy, Robert A. Montgomery, Kyle M. Redilla e Scott R. Winterstein. "The effect of habitat on the breeding season survival of Mallards (Anas platyrhynchos) in the Great Lakes region". Canadian Journal of Zoology 96, n. 7 (luglio 2018): 700–706. http://dx.doi.org/10.1139/cjz-2017-0224.

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Abstract (sommario):

Modeling the effect of habitat on animal survival is critical for understanding population dynamics and developing effective habitat management strategies. Despite the importance of this information, knowledge of survival–habitat associations are often lacking, particularly for waterfowl species. Here we evaluated female Mallard (Anas platyrhynchos Linnaeus, 1758) survival during the breeding season in relation to habitat conditions within each individual’s home range. We implanted telemetry transmitters and tracked 283 female Mallards across nine study sites in the Great Lakes region. For each Mallard, we quantified core breeding season home ranges via the creation of utilization distributions (UDs). We then fit known-fate models in the program MARK to predict breeding season survival as a function of the proximity of core home ranges to various habitat types, the proportion of habitat types within the core areas, number of core areas, and home range size. We found that breeding season survival decreased as the proportion of forestland habitat within core home ranges increased (β = −1.740, SE = 0.787). No additional upland or wetland habitat types significantly affected breeding season survival. Managers striving to increase breeding season survival for Mallards should focus their efforts on restoring habitats in areas with low proportions of forestland habitat to mitigate the risk of predation.

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19

Abood, Dhyaa Ab. "Comparative anatomical and histological features of the kidney in Harrier (Circus aueroginosus), Chicken (Gallus domesticus) and Mallard duck (Anas platyrhynchos". Iraqi Journal of Veterinary Medicine 38, n. 1 (1 giugno 2014): 107–13. http://dx.doi.org/10.30539/iraqijvm.v38i1.262.

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Abstract (sommario):

The aim of this study was to compare anatomical and histological of the kidney in three type of birds. The study revealed that, in harrier species the cranial lobe of kidney was the largest with elongated shape. In mallard the cranial lobe was small round-oval, while middle and caudal lobe were lobulated and larger .In chicken the caudal lobe was the largest. Statistically, in harrier the mean length of cranial lobe (20±0.1mm) and the width of the middle lobe (5±0.5mm) were significantly higher than those of mallard (10±0.3mm) (8.0.2mm) and chicken (15±0.2mm) (4±0.4mm) respectively. The mean weight of the kidney in harrier is (5.8±0.20g) this value significantly was higher than those of mallared (8.9±0.11g) and chicken (6.8±0.10g) in compare to the total body weight. Histologically, in harrier species the kidney had larger cortical region and the nephron types were numerous of mammalian type in medulla and few of reptilian type was presented in sub-capsular region. In mallard species the renal lobule was relatively divided into two equal cortical and medullary regions and the nephrons showed two types, numerous of mammalian and reptilian types presented in medulla and intermediate zone of kidney. In chickens the cortical region was the larger compared to medullary region which contained numerous mammalian types and few of reptilian type.

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20

Bombik, Elżbieta, Antoni Bombik e Katarzyna Pietrzkiewicz. "Content of Lead and Cadmium in the Tissues and Organs of the Wild Mallard Duck (Anas platyrhynchos L.) Depending on the Region of Poland Where It Is Harvested". Animals 13, n. 21 (26 ottobre 2023): 3327. http://dx.doi.org/10.3390/ani13213327.

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Abstract (sommario):

A property common to heavy metals is that even in small concentrations they can exert toxic effects on living organisms, including humans. The aim of this study was to analyze the quality of the tissues and organs of wild mallard ducks (Anas platyrhynchos L.) by estimating the potential hygiene and toxicological hazard associated with the concentrations of lead and cadmium in these tissues and organs, as well as the influence of the birds’ sex and place of origin on these parameters. A significantly higher average lead content was noted in the breast muscles and the livers of the mallards harvested in the Leszno hunting district compared to the birds from the Siedlce hunting district. A higher average cadmium concentration was recorded in the breast and leg muscles of the mallards harvested in the Leszno hunting district than the Siedlce hunting district. The concentration of cadmium in the tissues and organs of the mallards harvested in the Siedlce or the Leszno hunting district did not exceed the acceptable limits for the muscles and livers of slaughtered animals. This study found no significant effect of the sex of the wild crossbreeds on the content of lead and cadmium in tissues and organs. This study showed that the mallard has a measurable response to environmental pollution with lead and cadmium, and therefore it is a species that could to some extent be used as a bioindicator of the level of contamination of the environment with these xenobiotics. The ban on the use of lead pellets as ammunition in Poland may largely limit the degree of lead contamination of the tissues and organs of mallards.

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21

Dwyer, Chris P., e Guy A. Baldassarre. "Habitat use by sympatric female mallards and American black ducks breeding in a forested environment". Canadian Journal of Zoology 72, n. 9 (1 settembre 1994): 1538–42. http://dx.doi.org/10.1139/z94-204.

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Abstract (sommario):

There has been much speculation regarding whether breeding mallards (Anas platyrhynchos) and American black ducks (A. rubripes) use similar habitat types in forested areas, which could lead to increased interspecific contact. To study this issue, we used radiotelemetry during 1990–1991 on sympatric female mallards and black ducks breeding in the western Adirondack Mountains of New York. Mallard and black duck pairs occupied the general area at a density of 0.7 and 0.6/km2, respectively. Black duck home ranges tended to be larger than those of mallards, although the difference was not significant. Habitat composition within the home ranges of mallards and black ducks was similar, upland forest being the dominant habitat type, followed by wetlands, disturbed areas, and active residential sites. Within home ranges, mallards and black ducks were similar in their use of four major wetland habitat types. Our data suggest that undisturbed forest and habitat use within such areas may not serve as an isolating mechanism between breeding mallards and black ducks.

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22

Einarson, Daniel, Fredrik Frisk, Kamilla Klonowska e Charlotte Sennersten. "A Machine Learning Approach to Simulation of Mallard Movements". Applied Sciences 14, n. 3 (3 febbraio 2024): 1280. http://dx.doi.org/10.3390/app14031280.

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Abstract (sommario):

Machine learning (ML) is increasingly used in diverse fields, including animal behavior research. However, its application to ambiguous data requires careful consideration to avoid uncritical interpretations. This paper extends prior research on ringed mallards where sensors revealed their movements in southern Sweden, particularly in areas with small lakes. The primary focus is to distinguish the movement patterns of wild and farmed mallards. While well-known statistical methods can capture such differences, ML also provides opportunities to simulate behaviors outside of the core study span. Building on this, this study applies ML techniques to simulate these movements, using the previously collected data. It is crucial to note that unrefined application of ML can lead to incomplete or misleading outcomes. Challenges in the data include disparities in swimming and flying records, farmed mallards’ biased data due to feeding points, and extended intervals between data points. This research highlights these data challenges, while identifying discernible patterns, as well as proposing approaches to meet such challenges. The key contribution lies in separating incompatible data and, through different ML models, handle these separately to enhance the reliability of the simulation models. This approach ensures a more credible and nuanced understanding of mallard movements, demonstrating the importance of critical analysis in ML applications in wildlife studies.

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23

Salman, Alp, Irmak Kurtul e Hasan Musa Sarı. "The remarkable observation for a mallard (Anas platyrhynchos) food from estuarine/coastal area (İzmir/Turkey): A mosquitofish (Gambusia holbrooki)". Ege Journal of Fisheries and Aquatic Sciences 39, n. 3 (15 settembre 2022): 191–96. http://dx.doi.org/10.12714/egejfas.39.3.03.

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Abstract (sommario):

The purpose of this study is to create awareness about the species of mosquito fishes (Gambusia holbrooki Girard, 1859) both vectors and ways of introduction to new aquatic habitats. Because the species creates risks, especially for the circumstance of the native and endemic fish fauna, studies about introduction stories of the species are quite important to prevent the risk. In the current report, mosquitofishes which are known as a highly invasive species were found in the crop content of a hen mallard duck (Anas platyrhynchos L., 1758) in an estuarine area, the Gediz River Basin (İzmir, Turkey). This report is the first record of a duck consuming mosquitofish. Although nevertheless, it is known that mallard duck feeding behaviour does not predominantly contain fish (they mainly feed on plant seeds), according to this observation, mosquitofish might be added to the prey list of mallards as a new type of food. Therewith, this feeding behavior also indicates that ducks might be a potential vector for the transport of invasive mosquitofishes.

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24

Taylor-Burt, Kari R., Nicolai Konow e Andrew A. Biewener. "Post-activation muscle potentiation and its relevance to cyclical behaviours". Biology Letters 16, n. 6 (giugno 2020): 20200255. http://dx.doi.org/10.1098/rsbl.2020.0255.

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Abstract (sommario):

Muscle can experience post-activation potentiation (PAP), a temporary increase in force and rate of force development, when contractions are closely timed; therefore, cyclical behaviours are likely affected by PAP, as succeeding contraction cycles can lead to potentiation over several subsequent cycles. Here, we examined PAP during in situ cyclical contractions of the mallard lateral gastrocnemius (LG). Surface swimming, a cyclical behaviour, was mimicked with work-loops using in vivo LG length change and stimulation parameters. Tests were performed at mallards' preferred cycle frequency as well as at lower and higher frequencies. Like muscles from mammals, anurans and arthropods, the mallard LG exhibited PAP with increases in peak force, average force rate and net work. Staircase potentiation occurred over two or more work-loop cycles, resulting in gradual increases in PAP. The number of cycles needed to reach maximum work varied with cycle frequency, requiring more cycles at higher cycle frequencies. PAP occurred under in vivo -like stimulation parameters, suggesting a potentially important role of PAP in animal locomotion, especially in cyclical behaviours.

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25

Madokoro, Hirokazu, Satoshi Yamamoto, Kanji Watanabe, Masayuki Nishiguchi, Stephanie Nix, Hanwool Woo e Kazuhito Sato. "Mallard Detection Using Microphone Arrays Combined with Delay-and-Sum Beamforming for Smart and Remote Rice–Duck Farming". Applied Sciences 12, n. 1 (23 dicembre 2021): 108. http://dx.doi.org/10.3390/app12010108.

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Abstract (sommario):

This paper presents an estimation method for a sound source of pre-recorded mallard calls from acoustic information using two microphone arrays combined with delay-and-sum beamforming. Rice farming using mallards saves labor because mallards work instead of farmers. Nevertheless, the number of mallards declines when they are preyed upon by natural enemies such as crows, kites, and weasels. We consider that efficient management can be achieved by locating and identifying the locations of mallards and their natural enemies using acoustic information that can be widely sensed in a paddy field. For this study, we developed a prototype system that comprises two sets of microphone arrays. We used 64 microphones in all installed on our originally designed and assembled sensor mounts. We obtained three acoustic datasets in an outdoor environment for our benchmark evaluation. The experimentally obtained results demonstrated that the proposed system provides adequate accuracy for application to rice–duck farming.

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26

Sanderson, Glen C., William L. Anderson, George L. Foley, Karen L. Duncan, Loretta M. Skowron, Jeffrey D. Brawn e James W. Seets. "Toxicity of Ingested Bismuth Alloy Shot in Game-farm Mallards". Illinois Natural History Survey Bulletin 35, n. 1-5 (30 aprile 1997): 217–52. http://dx.doi.org/10.21900/j.inhs.v35.129.

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Abstract (sommario):

In a 150-day study, we tested for chronic toxicity and effects on reproduction of bismuth/tin (Bi/Sn) alloy shot dosed in game-farm mallards (Anas platyrhynchos). Histopathology of livers, kidneys, gonads, hearts, and lungs showed no significant group-related differences among 0-dosed (controls), iron (Fe)-dosed (8, No. 4, steel shot), and Bi-dosed (8, No. 4, Bi/Sn alloy shot) adult ducks or among ducklings from pairs of these dosed groups. Bi shot, under our test conditions, did not elicit toxicity in mallard ducks or affect their reproduction or offspring.

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27

Hughes, M. R., D. C. Bennett e T. M. Sullivan. "Effect of saline drinking water on the size and water content of the gut and other organs of male and female mallards". Canadian Journal of Zoology 80, n. 1 (1 gennaio 2002): 70–76. http://dx.doi.org/10.1139/z01-206.

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Abstract (sommario):

Ducks absorb imbibed Na+ and water in the anterior gut and reabsorb Na+ and water from urine refluxed into the hind gut. In Mallards (Anas platyrhynchos) this process is sexually disparate: males reflux and reabsorb more water, mainly in the ceca. We examined the effect of saline acclimation on the size of Mallard organs, especially the gut and other osmoregulatory organs (kidneys, salt glands) in both sexes. We tested and accept two hypotheses: (1) saline increases the mass of the Mallard hind gut and other osmoregulatory organs and (2) saline has a greater effect on the organs of males. Drinking saline did not affect the mass of body, kidney, heart, or liver, but increased the mass of the salt glands, ileum, and ceca. Increases in organ mass were greater in males than in females. Saline acclimation increased the length of the jejunum only in males and decreased the length of the esophagus and the length and mass of the proventriculus only in females. Our data suggest that the upper and lower gut segments may play somewhat different roles in ion and water transport in the two sexes.

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28

Seymour, N. R. "Forced copulation in sympatric American black ducks and mallards in Nova Scotia". Canadian Journal of Zoology 68, n. 8 (1 agosto 1990): 1691–96. http://dx.doi.org/10.1139/z90-249.

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Abstract (sommario):

Observations of primarily identifiable wild black ducks and mallards provided qualitative and quantitative descriptions of interactions within and between intraspecific, interspecific, and heterospecific pairs throughout the breeding season. The study was carried out in a watershed on the St. Lawrence estuary shore of Nova Scotia from 1972 to 1988. Attempted forced copulation and forced pair copulation were rare among black ducks at any time throughout the breeding period. Only two apparently successful forced copulations were observed. Territorial males chased both female black ducks and mallards, and these chases appeared motivated by hostility. Males that had left their mates/territories did not attempt forced copulation with other females. Females sometimes avoided strange males, particularly when they returned to territories from their nests. Paired males rarely approached females with broods. Male mallards chased both female mallards and black ducks, and did not appear to discriminate between species when attempting forced copulation. Male mallards were more persistent and vigorous in their chases than black ducks, and they attempted forced copulation, whether with black ducks or mallards, more frequently than male black ducks did. Apparently successful forced copulation between a male mallard and female black duck occurred on three occasions.

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29

Febrianto, Firman, Ismoyowati Ismoyowati, Mochamad Mufti, Prayitno Prayitno e Dattadewi Purwantini. "Polymorphisme Gene GH and Morphological Characteristic of Anas platyrhynchos and Cairina moschata". ANIMAL PRODUCTION 20, n. 1 (29 gennaio 2019): 17. http://dx.doi.org/10.20884/1.jap.2018.20.1.665.

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Abstract (sommario):

The aims of this research was to identify the qualitative and quantitative difference of the phenotypes of native mallard and Muscovy, and Muscovy the genetic diversity between Muscovy and mallard using RFLP method with growth hormone primer (GH) gene. The materials were 30-week old male and female ducks from 5 strains—Magelang, Mojosari and Tegal ducks, white-feathered, and black and white-feathered Muscovy. Muscovy Completely Randomized Design was used to analyze parameters 5 strains of ducks based on gender and with 5 replications. The parameters measured were local and Muscovy duck phenotypes and genetic diversity (number of alleles) based on GH gene, heterozygosity and genetic distance. Qualitative properties were analyzed descriptively and quantitative properties were analyzed using Anova followed by HSD in case of significant differences, whereas RFLP analysis was used to determine the allele frequencies, genotype frequencies, genetic diversity, and genetic distance of local ducks. Result showed phenotypic differences between Anas platyrhynchos and Cairina moschata. The dominant feather colorof Muscovy was black and white while mallard was brown. The bill color Muscovy Muscovy was pink with dark brown but black in mallard. The dominant shank’s color in both Muscovy and mallard was black. Body size of mallard was larger than that of Muscovy Muscovy, and Magelang ducks weigherd more than Tegal and Mojosari Duck. The PCR-RFLP results showed lower heterozygosity of mallard compared to Muscovy based on GH gene, and genetic distance of the Tegal duck was closer to Mojosari and Magelang ducks, whereas Magelang and Mojosari ducks had a considerable genetic distance based on the GH gene.

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30

Bartel, Riley D., Jennifer L. Sheppard, Ádám Lovas-Kiss e Andy J. Green. "Endozoochory by mallard in New Zealand: what seeds are dispersed and how far?" PeerJ 6 (23 maggio 2018): e4811. http://dx.doi.org/10.7717/peerj.4811.

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Abstract (sommario):

In Europe and North America waterfowl are major dispersers of aquatic and terrestrial plants, but in New Zealand their role has yet to be investigated. Mallards were introduced to New Zealand in the late 1800s, and today they are the most abundant and widespread waterfowl in the country. To assess seed dispersal, we radiomarked 284 female mallards from two study sites during the pre-breeding (June–August) and breeding (August–December) periods in 2014–2015, and examined movements that occurred within 24, 48 or 72 h when seed dispersal by endozoochory is considered likely. During June and July 2015, we collected 29 faecal samples from individual female mallards during radiomarking and 24 samples from mallard flocks. We recovered 69 intact seeds from the faecal samples and identified 12 plant taxa. Of the plant seeds identified and dispersed by mallards in this study, 40% were members of the Asteraceae family, nine plant species were alien to New Zealand, and the indigenous-status of three unidentified taxa could not be determined. Two taxa (and 9% of seeds) were germinated following gut passage: an unidentified Asteraceae andSolanum nigrum. During the pre-breeding and breeding periods, movement of females within 24 h averaged 394 m (SD = 706 m) and 222 m (SD = 605 m) respectively, with maximum distances of 3,970 m and 8,028 m. Maxima extended to 19,230 m within 48 h. Most plant species recorded are generally assumed to be self-dispersed or dispersed by water; mechanisms that provide a much lower maximum dispersal distance than mallards. The ability of mallards to disperse viable seeds up to 19 km within 48 h suggests they have an important and previously overlooked role as vectors for a variety of wetland or grassland plant species in New Zealand.

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31

Guay, P.-J., A. Taysom, R. Robinson e J. P. Tracey. "Hybridization between the Mallard and native dabbling ducks: causes, consequences and management." Pacific Conservation Biology 20, n. 1 (2014): 41. http://dx.doi.org/10.1071/pc140041.

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Abstract (sommario):

Waterbirds are currently facing various threats throughout the world. One threat that is often overlooked is hybridization with introduced species. This threatening process is especially significant for dabbling ducks (Genus Anas). The Mallard (Anas platyrhynchos) has been introduced to various parts of the world and now hybridizes and threatens numerous Anas species. In this paper, we review hybridization between Mallards and dabbling ducks with a specific emphasis on threats to the Pacific Black Duck (A. superciliosa). We then present an overview of the potential mechanisms of hybridization and discuss monitoring techniques. We conclude by proposing management strategies and speculating on the future of native dabbling duck species.

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32

Sheldon, William. "The Last Mallard". Organization & Environment 11, n. 4 (dicembre 1998): 477. http://dx.doi.org/10.1177/0921810698114016.

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33

Nummi, Petri. "Food-niche relationships of sympatric mallards and green-winged teals". Canadian Journal of Zoology 71, n. 1 (1 gennaio 1993): 49–55. http://dx.doi.org/10.1139/z93-008.

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Abstract (sommario):

Diets of juvenile green-winged teals (Anas crecca) and mallards (A. platyrhynchos) in August and September were studied with respect to (i) the proportion of animal and plant matter. (ii) prey size. (iii) prey diversity, and (iv) the vertical distribution of invertebrate prey in the water column. The size distribution of prey in the diets of the ducks was also compared with that in the environment. Teal diets contained a larger and more variable fraction of invertebrates than did mallard diets. Teals used more small food items than did mallards; however, both used a wide spectrum of sizes. Teals ate more invertebrates that live in the water column or above the water surface, whereas mallards ate more benthic animals. These results contradict earlier studies that had classified teals, on the basis of digestive tract morphology, as more herbivorous than mallards. Therefore, inferences about differences in diet based on morphology alone should be made with some caution. I also suggest, contrary to some earlier studies, that both teals and mallards are generalist foragers, the teal being probably even more plastic when different modes of aquatic feeding are considered.

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34

Fedynich, Alan M., e Danny B. Pence. "Helminth community structure and pattern in a migratory host (Anas platyrhynchos)". Canadian Journal of Zoology 72, n. 3 (1 marzo 1994): 496–505. http://dx.doi.org/10.1139/z94-067.

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Abstract (sommario):

The helminth community at the southern periphery of the mallard (Anas platyrhynchos) breeding range on the Southern High Plains of Texas consisted of species commonly reported in this host at northern latitudes. Although prevalence, abundance, and dominance values varied and this helminth community was species-rich and diverse, species composition was relatively consistent over temporal and host variables. Mallards had higher mean abundances of helminths in summer than winter; 80% of all helminth individuals occurred in juveniles. Recurrent groups formed during summer and within juvenile mallards were larger and more complex than groups formed during winter or in adults. Of the 15 helminth species forming group memberships, only Cloacotaenia megalops, Microsomacanthus hopkinsi, Amidostomum acutum, and Tetrameres spp. commonly co-occurred during each of four seasons in juvenile mallards, whereas C. megalops and Capillaria contorta persisted temporally in adult mallards. These species occupy different host microhabitats, suggesting little or no interaction between temporally persistent species that commonly co-occur in mallards. The results of our study suggest that helminth communities reflect the density distribution of the host species across their annual geographic range, where the breeding range represents the epicenter of origin for this host–helminth system.

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35

Krementz, David G., Kwasi Asante e Luke W. Naylor. "Autumn Migration of Mississippi Flyway Mallards as Determined by Satellite Telemetry". Journal of Fish and Wildlife Management 3, n. 2 (1 dicembre 2012): 238–51. http://dx.doi.org/10.3996/022012-jfwm-019.

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Abstract (sommario):

Abstract We used satellite telemetry to study autumn migration timing, routes, stopover duration, and final destinations of mallards Anas platyrhynchos captured the previous spring in Arkansas from 2004 to 2007. Of those mallards that still had functioning transmitters on September 15 (n = 55), the average date when autumn migration began was October 23 (SE = 2.62 d; range = September 17–December 7). For those mallards that stopped for >1 d during migration, the average stopover length was 15.4 d (SE = 1.47 d). Ten mallards migrated nonstop to wintering sites. The eastern Dakotas were a heavily utilized stopover area. The total distance migrated per mallard averaged 1,407 km (SE = 89.55 km; range = 142–2,947 km). The average time spent on migration per individual between September 15 and December 15 was 27 d (SE = 2.88 d; range = 2–84 d). The state where most mallards were located on December 15 was Missouri (11) followed by Arkansas (8), while 5 mallards were still in Canada, and only 8 of 43 females and 0 of 10 males were present in Arkansas. The eastern Dakotas are a heavily utilized migration stopover for midcontinent mallards that may require more attention for migration habitat management. The reasons for so few mallards, especially male mallards, returning to Arkansas the following year deserves further research.

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36

Torrella, J. R., V. Fouces e G. Viscor. "Descriptive and functional morphometry of skeletal muscle fibres in wild birds". Canadian Journal of Zoology 77, n. 5 (1 ottobre 1999): 724–36. http://dx.doi.org/10.1139/z99-011.

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Abstract (sommario):

The fibre types of four forelimb and two hind-limb muscles involved in locomotion were morphometrically analyzed in three species of wild birds: the mallard (Anas platyrhynchos), common coot (Fulica atra), and yellow-legged gull (Larus cachinnans). Fibre cross-sectional area and perimeter, maximal diffusion distance, and number of capillaries per fibre were measured and the functional implications and physiological demands of the muscles of each species were inferred. In general, all morphometric values were lower in oxidative fibres than in anaerobic fibres, indicating that the supply of oxygen and metabolites available to aerobically working muscles is enhanced. The lower level of activity required during gliding as opposed to flapping flight, and the need to maintain the wings in an outstretched position, presumably by means of isometric contractions, may explain the greater size of the oxidative fibres of the pectoralis and scapulotriceps muscles of the gull. In contrast, the high oxidative demand imposed on mallards and coots by sustained flapping flight is met by small oxidative fibres, possibly at the expense of a reduction in the ability of each fibre to generate force. Anaerobic fibres of the gastrocnemius muscle had greater cross-sectional areas in the mallard and coot than in the gull. This is interpreted as an adaptive response to force generation during burst locomotion, which is usually performed by both mallards and coots, in sharp contrast to the buoyant swimming and postural activities undertaken by gull's legs. The fast oxidative fibres of the gastrocnemius muscle were, in general, larger than those of the iliotibialis muscle in the three species, which matches the different mechanical and functional roles of these muscles during swimming.

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37

Schott, Renée. "Surgical Repair of Ankyloblepharon in Mallards (Anas platyrhynchos)". Wildlife Rehabilitation Bulletin 26, n. 2 (31 dicembre 2008): 31–35. http://dx.doi.org/10.53607/wrb.v26.151.

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Abstract (sommario):

Congenital and acquired ankyloblepharon (complete fusion of the upper and lower eyelids) have been documented in birds (Buyukmihci et al 1990; Pinard et al 2006). Surgical repair of ankyloblepharon in cockatiels (Nymphicus spp.) has been reported as unsuccessful in four cases of presumed congenital origin and successful in one case of acquired ankyloblepharon (Buyukmihci et al 1990; Pinard et al 2006). Two mallards (Anas platyrhynchos) with ankyloblepharon were treated with surgical reconstruction of the eyelids to restore bilateral vision. The first mallard presented as a one–week old orphan. Physical exam findings were normal except for a small amount of mucopurulent discharge from the left eye. Surgical reconstruction of the eyelids was performed successfully, with signs of wound contracture two weeks post–operatively, but no further closure at the three–week recheck. A full thickness corneal scar, anterior synechia, and small cataract were noted during surgery that suggest trauma as a cause for the ankyloblepharon. The second mallard presented with ankyloblepharon of unknown etiology. The first surgical reconstruction was unsuccessful, however a second attempt, using a more rigorous surgical eyelid excision, was successful with no further closure of the palpebral fissure at follow–up two months later. Moderate pododermatitis was successfully treated using systemic antibiotics and Collasate (PRN Pharmacal, Pensacola, FL) regimen.

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38

Trovão, Nídia S., Jacqueline M. Nolting, Richard D. Slemons, Martha I. Nelson e Andrew S. Bowman. "The Evolutionary Dynamics of Influenza A Viruses Circulating in Mallards in Duck Hunting Preserves in Maryland, USA". Microorganisms 9, n. 1 (25 dicembre 2020): 40. http://dx.doi.org/10.3390/microorganisms9010040.

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Abstract (sommario):

Duck hunting preserves (DHP) have resident populations of farm-raised mallard ducks, which create potential foci for the evolution of novel influenza A viruses (IAVs). Through an eleven-year (2003–2013) IAV surveillance project in seven DHPs in Maryland, USA, we frequently identified IAVs in the resident, free-flying mallard ducks (5.8% of cloacal samples were IAV-positive). The IAV population had high genetic diversity, including 12 HA subtypes and 9 NA subtypes. By sequencing the complete genomes of 290 viruses, we determined that genetically diverse IAVs were introduced annually into DHP ducks, predominantly from wild birds in the Anatidae family that inhabit the Atlantic and Mississippi flyways. The relatively low viral gene flow observed out of DHPs suggests that raised mallards do not sustain long-term viral persistence nor do they serve as important sources of new viruses in wild birds. Overall, our findings indicate that DHPs offer reliable samples of the diversity of IAV subtypes, and could serve as regional sentinel sites that mimic the viral diversity found in local wild duck populations, which would provide a cost-efficient strategy for long-term IAV monitoring. Such monitoring could allow for early identification and characterization of viruses that threaten bird species of high economic and environmental interest.

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39

Mack, Glenn G., Robert G. Clark e David W. Howerter. "Size and habitat composition of female mallard home ranges in the prairie-parkland region of Canada". Canadian Journal of Zoology 81, n. 8 (1 agosto 2003): 1454–61. http://dx.doi.org/10.1139/z03-136.

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Wetland density is believed to be an important determinant of variation in size of mallard (Anas platyrhynchos) home ranges, but hypothesized effects of upland habitat and female size and age have not been adequately evaluated. Thus, we investigated correlates of home-range size using unique radio-tracking data for 131 female mallards studied on 12 Canadian prairie-parkland sites in 19951998. Home-range size and habitat composition varied within and among study areas; overall, variation in home-range size was best modeled to include effects of seasonal and semipermanent wetlands (β = 0.06 ± 0.01; mean ± SE) and woodlandshrubland habitat (β = 0.03 ± 0.01). Contrary to predictions, we obtained no support for a positive association between home-range size and female body size or a negative relationship between home-range size and female age. After controlling for confounding effects of wetland density, home ranges were larger, on average, on study areas with lower densities of mallard breeding pairs; therefore, we suspect that individual home ranges were smaller in areas of high pair density because of increased intraspecific competition for breeding space. A higher proportion of woodlandshrubland habitat likely contributed to the smaller size of individual home ranges because of a greater relative availability of preferred nesting habitat.

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40

Söderquist, Pär, Camilla Olsson, Karina Birch e Viktoria Olsson. "Evaluation of Nutritional Quality and Sensory Parameters of Meat from Mallard and Four Species of Wild Goose". Foods 11, n. 16 (17 agosto 2022): 2486. http://dx.doi.org/10.3390/foods11162486.

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Future challenges concerning protein supply for food and feed include the management of all currently available resources. In Sweden, wildfowl are hunted for several reasons, one of which is to protect growing crops. In this study, meat from wild geese and mallard was evaluated with respect to its quality and sensory parameters. The most pronounced sensory differences were between meat from the barnacle goose and the Canada goose and between meat from mallards that were farmed and born wild. This study also provides measurements of values for the nutritional and heavy metal contents of the meat from these wildfowl species in order to elucidate their possible use as modern foods.

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Andersson, Stina, Daniel Bengtsson, Magnus Hellström e Jonas Waldenström. "Age and sex determination of Mallards Anas platyrhynchos in autumn". Ornis Svecica 26, n. 2 (1 aprile 2016): 61–81. http://dx.doi.org/10.34080/os.v26.22530.

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Male and female mallards Anas platyrhynchos are easily told apart, whereas ageing is problematic, due to individual timing of moult and lack of easily defined age criteria. From examination and photographic documentation of mallards caught at Ottenby Bird Observatory (56°12′N, 16°24′E), we describe nine characters of plumage and bare parts to be used for ageing in autumn. The reliability of these characters was tested by letting experienced bird ringers determine putative age of birds from photos. Age determination from any single character proved to be uncertain, as correctly assigned mallard photos of each character was in the range of 51–85% for males and 48–89% for females. For both sexes, the lowest figure represented post-humerals and the highest represented tertials. Rectrices, tertial coverts, and greater coverts had high scores (71–85%). Using all characters, 91% of the males and 95% of the females were correctly aged. As young mallards, with the progress of pre-breeding moult (completed from October onwards), acquire tail and tertials identical to adults, untypical individuals are better not assigned to an age category.

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42

Karaca, T., M. Cemek e M. Kanter. "Lipid Peroxidation, Antioxidant Level, and Alpha Naphthyl Acetate Esterase Activity of Peripheral Blood Lymphocytes in the Mallard, Muscovy and Pekin Ducks". Acta Veterinaria Brno 75, n. 1 (2006): 33–38. http://dx.doi.org/10.2754/avb200675010033.

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The aim of this study was to determine blood levels of malondialdehyde (MDA), reduced glutathione (GSH), ceruloplasmin and vitamin C, and the percentages of peripheral blood Tlymphocytes using the alpha-naphthyl acetate esterase (ANAE) method on Mallard (Anas platyrhynchos), Muscovy (Cairina moschata) and Pekin (Anas domestica) ducks. Blood samples were obtained from 8 adult ducks of each breed. The serum levels observed in Mallard, Muscovy and Pekin ducks respectively were 0.8, 1.07 and 1.3 nmol MDA per ml; 77.4, 66.9 and 78.7 mg GSH per 100 ml; 23.9, 26.1 and 24.1 mg ceruloplasmin per 100 ml; and 0.50, 0.52 and 0.70 mg vitamin C per 100 ml. The percentage of the ANAE (+) lymphocytes was 57.9%, 54.8% and 55.1% in Mallard, Muscovy and Pekin ducks, respectively. In this study, blood levels of lipid peroxidation and nonenzymatic antioxidants in the Mallard, Muscovy and Pekin ducks were determined.

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43

Kelava Ugarković, Nikolina, Dalibor Bedeković, Kristina Greiner, Nera Fabijanić, Zvonimir Prpić e Miljenko Konjačić. "Carcass Characteristics and Meat Quality of Wild-Living Mallard (Anas platyrhynchos L.) Originating from Croatia". Foods 13, n. 10 (13 maggio 2024): 1519. http://dx.doi.org/10.3390/foods13101519.

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The aim of this study was to determine the effects of sex and hunting location on carcass characteristics and meat quality of wild-living mallard (Anas platyrhynchos) from Croatia. Twenty-eight mallards (14 ♂; 14 ♀) were hunted at two hunting locations (HL I = 8 ♂, 8 ♀; HL II = 6 ♂, 6 ♀) in the Croatian lowlands. The carcasses were eviscerated, dressed, and dissected, and the individual internal organs and carcass parts were weighed. The breast muscle (m. pectoralis major) was sampled and used to determine color, pH, drip loss, cooking loss, shear force, and proximate chemical and fatty acid composition. Sex and HL had a significant effect on the majority of carcass characteristics analyzed, but they had no effect on the physical meat parameters. The protein and ash content of mallard meat was significantly higher in HL II (23.16% vs. 22.67%; 1.45% vs. 1.36%, respectively) and the moisture content in females (72.40% vs. 71.59%). HL had a significant effect on SFA (II 33.96% vs. I 29.91%), PUFA n-3 (II 3.55% vs. I 2.69%), PUFA/SFA and n-6/n-3 ratios, and all lipid indices. Females had a significantly higher C22:6n-3 content, a higher PI index and a lower n-6/n-3 ratio. The data presented in this study contribute to a better understanding of game-bird meat quality originating from different regions.

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44

Pehrsson, Olof. "Egg and clutch size in the mallard as related to food quality". Canadian Journal of Zoology 69, n. 1 (1 gennaio 1991): 156–62. http://dx.doi.org/10.1139/z91-024.

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The effect of food quality on egg and clutch size was studied in captive wild-strain and game-farm mallards, Anas platyrhynchos, and comparisons were made with various wild Swedish populations from different habitat types. Captive mallards laid larger eggs than wild birds. In captivity, game-farm ducks laid larger eggs than wild-strain birds, but when they were exposed to wild conditions the size was reduced. Captive ducks supplied with high-protein food laid larger eggs than ducks fed low-protein food. In the wild, there was a negative correlation between egg size and population density. Various wild Swedish populations showed similar egg-size variations among years, indicating some common factor operating outside the breeding season. In the food quality experiments, clutch size was positively correlated with egg size, but no correlation was found in wild populations. A negative correlation between clutch size and laying date, obtained in the wild, was not found in captivity. Egg and clutch sizes were both significantly smaller in a lake with food competition from fish than in an area rich in lakes empty of fish. When comparing egg characteristics of mallard populations it is important to distinguish between wild, captive wild-strain, and captive game-farm birds.

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45

Arnold, Todd W., David W. Howerter, James H. Devries, Brian L. Joynt, Robert B. Emery e Michael G. Anderson. "Continuous Laying and Clutch-Size Limitation in Mallards". Auk 119, n. 1 (1 gennaio 2002): 261–66. http://dx.doi.org/10.1093/auk/119.1.261.

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Abstract We assessed nutritional constraints on clutch size in Mallards (Anas platyrhynchos) by observing incidence and consequences of continuous laying—the sequential production of eggs in two or more nest bowls. Continuous laying behavior was detected in 278 of 3,064 radiotracked Mallards (9.1%). Continuous laying females produced an average of 12.12 total eggs (SD = 2.70, range 5–18, n = 69), versus 8.90 eggs for normal nesting females (SD = 1.67, range 4–14, n = 587). On average, continuous laying females were 25 g heavier than noncontinuous laying females, and body mass was positively correlated with egg production among continuous laying females. Nest success was not affected by continuous laying, but continuous laying females that abandoned their nests were more likely to be young or to have laid a greater number of eggs. A large component of the breeding Mallard population can lay more eggs than they typically do, and there appear to be minimal consequences of that behavior. These observations appear inconsistent with the egg-formation hypothesis.

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46

Hutařová, Zdeňka, Olga Čelechovská, Vladimír Večerek e Zdeňka Svobodová. "The impact of using lead pellets on lead contamination of mallards (Anas platyrhynchos) in the Czech Republic". Acta Veterinaria Brno 82, n. 1 (2013): 55–59. http://dx.doi.org/10.2754/avb201382010055.

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The aim of the study was to assess the degree of lead contamination in mallards in the Czech Republic as a result of using lead shots for wildfowling. Two sites used for mallard hunting were chosen, namely a flood-control reservoir in Moravia and a small fishpond in Bohemia. Lead concentrations were determined in the tissues of 20 mallards (Anas platyrhynchos) raised at those standing open water sites (n = 10 at each site) and killed there during the autumn hunting season with a steel shot. Control groups were made up of 20 mallards from the same breeding facility as experimental groups but raised in an enclosure without access to water (n = 10 at each site). Lead concentrations were determined in selected tissues (breast muscle, heart, liver, gizzard, kidney, feathers - quill base, lung, brain and humerus) by high resolution continuum source atomic absorption spectrometry. The results showed elevated lead concentrations in all tissues of mallards compared with control in the reservoir in Southern Moravia. The highest lead concentrations (mg/kg) were found in the humerus (14.254 ± 4.525 and 5.083 ± 0.748 for experimental and control mallards, respectively). In contrast, lead concentrations in mallards from small fishpond in Southern Bohemia were lower compared to control. Similarly, the highest lead concentrations were found in the humerus (2.219 ± 0.349 and 8.930 ± 1.012 for experimental and control mallards, respectively). This study extends very limited information about lead contamination of wild ducks in the Czech Republic in connection with hunting activities.

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47

Madokoro, Hirokazu, Satoshi Yamamoto, Yo Nishimura, Stephanie Nix, Hanwool Woo e Kazuhito Sato. "Prototype Development of Small Mobile Robots for Mallard Navigation in Paddy Fields: Toward Realizing Remote Farming". Robotics 10, n. 2 (27 aprile 2021): 63. http://dx.doi.org/10.3390/robotics10020063.

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This study was conducted to develop robot prototypes of three models that navigate mallards to achieve high-efficiency rice-duck farming. We examined two robotics navigation approaches based on imprinting and feeding. As the first approach, we used imprinting applied to baby mallards. They exhibited follow behavior to our first prototype after imprinting. Experimentally obtained observation results revealed the importance of providing imprinting immediately up to one week after hatching. As another approach, we used feed placed on the top of our second prototype. Experimentally obtained results showed that adult mallards exhibited wariness not only against the robot, but also against the feeder. After relieving wariness with provision of more than one week time to become accustomed, adult mallards ate feed in the box on the robot. However, they ran away immediately at a slight movement. Based on this confirmation, we developed the third prototype as an autonomous mobile robot aimed for mallard navigation in a paddy field. The body width is less than the length between rice stalks. After checking the waterproof capability of a body waterproof box, we conducted an indoor driving test for manual operation. Moreover, we conducted outdoor evaluation tests to assess running on an actual paddy field. We developed indoor and outdoor image datasets using an onboard monocular camera. For the outdoor image datasets, our segmentation method based on SegNet achieved semantic segmentation for three semantic categories. For the indoor image datasets, our prediction method based on CNN and LSTM achieved visual prediction for three motion categories.

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48

Gaviola, Isagani Q., Manuel D. Gacutan Jr., Warren D. Come e Karen Luz T. Yap. "Supplementary Effect of Ensiled Ficus Fruit [Ficus nota (Blanco) Merr.] on The Growth Performance in Mallard Ducks [Anas platyrhynchos (Linnaeus), 1758]". International Journal of Multidisciplinary: Applied Business and Education Research 5, n. 6 (23 giugno 2024): 2134–41. http://dx.doi.org/10.11594/ijmaber.05.06.16.

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A study was conducted to determine the effects of supplementing the ensiled ficus (EFF) fruit on the growth performance of mallard ducks. One hundred seventy-five (175) day old straight-run mallard ducklings were assigned with the following diets: A (control), B (5% EFF inclusion), C (10% EFF inclusion), D (15% EFF inclusion), and E (20% EFF inclusion) following Randomized Complete Block Design (RCBD) with cage location as blocking factor. Data were run in general linear model of SAS v.9.4. TS1M8 and difference among treatments were determined using trend comparison and declared significant at =0.05. Results showed the ensiling can improve the chemical composition of the ficus fruits and make it favorable to mallard ducks when supplemented. The effect of supplementing EFF in mallard ducks showed a general increase in VFI with higher inclusion rate of EFF with comparable BW and WG. However, FCR was a bit higher with ducks given increasing EFF supplement. Lastly, RFCC was also lower in diets with EFF compared to the control group.

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49

MacKinnon, Nancy M. "Unpaired Drake Avoidance Behaviour and Mate Recognition by Female Mallard, Anas platyrhynchos, During the Spring Breeding Season". Canadian Field-Naturalist 123, n. 1 (1 gennaio 2009): 70. http://dx.doi.org/10.22621/cfn.v123i1.676.

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An observation of a female Mallard (Anas platyrhynchos) avoiding unpaired drakes, in breeding season, until reuniting with her mate after audio recognition of the rähb call. This observation supports the supposition that this vocalization by the male Mallard is a response to separation from the female and functions as a contact call in mate recognition.

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50

Titman, Rodger, Elise Titman e Shawn Craik. "Timing of pair formation and male acquisition of alternate plumage by three wintering dabbling ducks". Canadian Field-Naturalist 135, n. 1 (23 giugno 2021): 39–46. http://dx.doi.org/10.22621/cfn.v135i1.2547.

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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.

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