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opencc-zeroFeb 2022View details →

Stomach content, biomass, abundance and body score of long-tailed ducks (Clangula hyemalis) from south-eastern Baltic Sea

The long-tailed duck (Clangula hyemalis) is a vulnerable and declining species wintering in the Baltic Sea. The introduction of the invasive fish, the round goby (Neogobius melanostomus), dramatically impacted the benthic macrofauna in hard-bottom, while no significant changes occurred in soft-bottom benthic macrofauna. Therefore, we aimed to assess the extent to which the diet of long-tailed duck changed in two different bottom types. We analysed the stomach content of 251 long-tailed ducks bycaught in gillnets from 2016 to 2020 in hard- and soft-bottom habitats and compared these results with those published by Žydelis and Ruškyte (2005). The results show that the long-tailed duck experienced a change in diet in hard-bottom habitats, shifting from the blue mussel to Hediste diversicolor, barnacles and fish. In soft-bottom habitats, their diet remained similar over time and was based on H. diversicolor, a few bivalve species and Saduria entomon. There was no evidence of significant differences in diet neither between sex nor age. Despite the above-mentioned changes in diet, the average body condition of the species did not change neither over time nor between habitats. This confirms that long-tailed ducks have high feeding flexibility and quick species response to changes in prey availability, as they are capable of shifting their diet to new prey.

opencc-zeroFeb 2022View details →

Temporal and interspecific dietary variation in wintering ducks in agricultural landscapes

Farmlands are becoming more important as waterfowl foraging habitats, while natural wetlands are being lost globally. However, it is unclear how waterfowl coexist in agricultural landscapes by resource partitioning. We evaluated the diets of seven sympatric dabbling ducks foraging in rice paddy and lotus fields around Lake Kasumigaura, the second largest lake in Japan, during two wintering seasons (from November to February) by fecal DNA metabarcoding using chloroplast trnL and mitochondrial CO1 region sequences. We examined 420 fecal samples and found different patterns of dietary diversity and composition among the duck species. The pattern also differed between plant and invertebrate food. Dietary niche partitioning was clear in plant food. Large-bodied ducks intensively use crop plants, and other ducks might mediate competition by using terrestrial and aquatic plants that are suitable for their foraging behaviors or microhabitats. Dietary segregation among species was the most apparent in February, when the abundance of foraging ducks was the largest. This study illustrated the complex pattern of dietary niche partitioning of dabbling ducks in agricultural landscapes, which might be difficult to evaluate by conventional approaches. The availability of crop plants, as well as other plant food resources in flooded areas and farmland dikes, may enable ducks to coexist by spatial or behavioral resource partitioning.

opencc-zeroMay 2022View details →

Pacific black ducks tri-axial accelerometer data with behaviour labels

The tri-axial accelerometer datasets from Pacific black ducks (Anas superciliosa) was measured at 25 Hz. Fifty tri-axial measurements, totalling 2 seconds, were used to form a behaviour segment. Each dataset includes 9343 segments each forming a row in the dataset. Each row contains 151 columns. The first 150 columns are ACC measurements from three orthogonal axes, arranged as x, y, z, x, y, z, ...,x, y, z. The final column is of type character containing the corresponding behaviour. The two datasets contains 16 and 8 behaviour type labels, respectively.

opencc-by-4.0Jun 2022View details →

Aeolian Saltation Data at Duck, NC - 4 August 2020

Datasets of sequence linescan lidar, Sensit aeolian sediment transport data, and wind measurements were collected at the US Army Engineer Research and Development Center's Field Research Facility on 4 August 2020 associated with the passage of the Tropical Storm Isaias.    Dataset 1. Matlab .mat files are provided with 30 minutes of linescan lidar data, with the following variables; Xmat = cross-shore distance of each point in meters in the US Army Corps of Engineers Field Research Facility local coordinate system Ymat = alongshore distance of each point in meters in the US Army Corps of Engineers Field Research Facility local coordinate system Zmat = vertical elevation of each point in meters in the NAVD88 datum Amat = amplitude of returned lidar signal Tmat = time of each point sample in matlab format reflectance = reflectance of the returned lidar signal Each lidar linescan measures at approximately 7.1 Hz for 30 continuous minutes. The filenames include the date in yyyymmdd-HHMM-SS format for the start time of the scan.  Dataset 2: Processed saltation height data generated from the point clouds are provided as a grid in 'IsaiasLidarSaltationHeight_202008040900to202008041500.mat' . The variables in the file are 'saltation_times' which are 1s time intervals in matlab format, 'saltation_distances' which are 0.1 m grid cells in the FRF cross-shore coordinate system, and 'SALTATION_HEIGHT_m'  providing the lidar-derived maximum saltation height for each grid cell and time interval with available data between 4 August 2020 0900 UTC to 4 August 2020 1500 UTC. Dataset 3: An excel spreadsheet entitled "InSituData.xlsx' provides time series data of 1Hz wind speed  using a Dyacon WSD-1 cup anemometer collected from a 5 m mast on the beach and logged using a Dyacon MDL-700 data logger. 1 Hz data of sediment counts from a stacked array of Sensit H14-LIN horizontal flux sensors, which were logged using a Campbell CR1000X logger, and were located at 8 cm, 12 cm, and 16 cm off of the bed in close proximity to the lidar are also provided.

opennotspecifiedJul 2022View details →

FIGURE. Dicorynia paraensis, var. ingens, var. macrophylla and floral diagram to D. paraensis. A–C. Dicorynia paraensis var. macrophylla; A. Branch with leaves; B. Axillary bud; C. Petiolule and base of the leaflet; D–G. Dicorynia paraensis var. ingens; D. Branch with a leaf; E. Axillary bud; F. Petiolule and base of the leaflet; G. Detail of the abaxial face of the leaflet presenting dark glandular trichomes; H. Floral diagram of D. paraensis, arrows represent bracts and asterisks represent lateral flowers in a cymose subunit. A: D. Cardoso 3397; B–C: A. Ducke s.n. RB231037; D–G: A. Ducke s.n. MG16022. Drawn by M. Falcão. Scale bar. A, D: 3 cm; B–C, E–F: 2mm; G: 0.1mm. in A Taxonomic Revision of the Amazonian Genus Dicorynia (Fabaceae: Dialioideae)

FIGURE. Dicorynia paraensis, var. ingens, var. macrophylla and floral diagram to D. paraensis. A–C. Dicorynia paraensis var. macrophylla; A. Branch with leaves; B. Axillary bud; C. Petiolule and base of the leaflet; D–G. Dicorynia paraensis var. ingens; D. Branch with a leaf; E. Axillary bud; F. Petiolule and base of the leaflet; G. Detail of the abaxial face of the leaflet presenting dark glandular trichomes; H. Floral diagram of D. paraensis, arrows represent bracts and asterisks represent lateral flowers in a cymose subunit. A: D. Cardoso 3397; B–C: A. Ducke s.n. RB231037; D–G: A. Ducke s.n. MG16022. Drawn by M. Falcão. Scale bar. A, D: 3 cm; B–C, E–F: 2mm; G: 0.1mm.

opennotspecifiedJul 2022View details →

FIGURE. Varieties of Dicorynia paraensis. A. Dicorynia paraensis var. paraensis; B. Dicorynia paraensis var. macrophylla; C. Dicorynia paraensis var. uaupensis; D. Dicorynia paraensis var. ingens. A: Spruce, R. 1918; B: Ducke, A. s.n. RB23321; C: Amaral, I.L. 574; D: Ducke, A. s.n. MG15707(S). Images by: A: Paris Virtual Herbarium; B-D: Reflora. Scale bar: 5cm. in A Taxonomic Revision of the Amazonian Genus Dicorynia (Fabaceae: Dialioideae)

FIGURE. Varieties of Dicorynia paraensis. A. Dicorynia paraensis var. paraensis; B. Dicorynia paraensis var. macrophylla; C. Dicorynia paraensis var. uaupensis; D. Dicorynia paraensis var. ingens. A: Spruce, R. 1918; B: Ducke, A. s.n. RB23321; C: Amaral, I.L. 574; D: Ducke, A. s.n. MG15707(S). Images by: A: Paris Virtual Herbarium; B-D: Reflora. Scale bar: 5cm.

opennotspecifiedJul 2022View details →

FIGURE. Terminal and axillary buds in Dicorynia. Terminal bud with a lateral axillary bud on left in: A. D. guianensis and; B. D. paraensis var. uaupensis; C. D. guianensis: axillary bud laterally obovate; D. D. paraensis var. paraensis: axillary bud laterally narrowly lanceolate; E. D. paraensis var. macrophylla: axillary bud, laterally oblong and acuminate; F. D. paraensis var. macrophylla: axillary bud elliptical, pedunculate and with obtuse apex; G. D. paraensis var. uaupensis; typical axillary bud, laterally narrowly obovate and acuminate (note in B an orbicular example in the same variety); H. D. paraensis var. ingens: axillary bud orbicular. A, C: Stahel s.n. RB756216; B: Ducke, A. s.n. RB20337; D: Ducke, A. s.n. RB24185; E: Ducke, A. s.n. RB231037; F: Falcão, M.J. 90; G: Amaral, I.L. 618; H: Ducke, A. s.n. MG16022. Scale bar: 2 mm. in A Taxonomic Revision of the Amazonian Genus Dicorynia (Fabaceae: Dialioideae)

FIGURE. Terminal and axillary buds in Dicorynia. Terminal bud with a lateral axillary bud on left in: A. D. guianensis and; B. D. paraensis var. uaupensis; C. D. guianensis: axillary bud laterally obovate; D. D. paraensis var. paraensis: axillary bud laterally narrowly lanceolate; E. D. paraensis var. macrophylla: axillary bud, laterally oblong and acuminate; F. D. paraensis var. macrophylla: axillary bud elliptical, pedunculate and with obtuse apex; G. D. paraensis var. uaupensis; typical axillary bud, laterally narrowly obovate and acuminate (note in B an orbicular example in the same variety); H. D. paraensis var. ingens: axillary bud orbicular. A, C: Stahel s.n. RB756216; B: Ducke, A. s.n. RB20337; D: Ducke, A. s.n. RB24185; E: Ducke, A. s.n. RB231037; F: Falcão, M.J. 90; G: Amaral, I.L. 618; H: Ducke, A. s.n. MG16022. Scale bar: 2 mm.

opencc-zeroOct 2022View details →

Generation of hybrids in broadly sympatric ducks

Although rare, hybrids are more common in broadly sympatric waterfowl than in any other avian family; yet, the behavioral ecology explaining their generation has remained controversial. Leading hypotheses are forced interspecific copulations, mis-imprinting caused by mixed broods, and scarcity of conspecific mates. Using a large sample of hybrid ducks solicited from North American hunters we evaluated these hypotheses by genetically determining the mother and father species of F1 hybrids. Based on abundances in areas where their breeding ranges overlap, the frequency of hybrids varied greatly from expectations, with hybrids between species within recently derived clades being much more frequent than those between more divergent clades. Forced copulations, as measured by large phallus length asymmetries between parentals, strongly predicted the father species of most F1 hybrids. Thus, most Anas acuta x A. platyrhynchos (Northern Pintail x Mallard) F1s were sired by A. acuta, and most A. platyrhynchos x Mareca strepera (Mallard x Gadwall) F1s were sired by A. platyrhynchos. Siring asymmetries were consistent with phallus length asymmetries in five additional parental combinations, but none had samples large enough to be individually statistically significant. The exception to this trend was our sample of nine A. platyrhynchos x Mareca americana (Mallard x Gadwall) F1s, for which a large phallus asymmetry failed to predict the father species. Hybrids were rare in brood parasitic species, suggesting mis-imprinting to be an unlikely cause of most hybrids; however, our samples of hybrids from regular brood parasites were inadequate to strongly address this hypothesis. We could test the scarcity of mates hypothesis for only a single hybrid combination and it contradicted our prediction: most F1 M. Penelope x M. americana (Eurasian x American Wigeon) were sired by M. penelope, strongly contradicting our prediction that female M. penelope wintering in enormous flocks of M. americana (American Wigeon) on the west coast of North America would have difficulty finding conspecific mates. In general, our results support interspecific forced copulations as the predominant behavioral mechanism generating hybrids in North temperate waterfowl.

opennotspecifiedJun 2017View details →

FIGURE 6. Discolobium tocantinum Ducke. A. Branch with leaf and inflorescence. B. Leaflet. C. Bract. D. Bracteole. E. Calyx. F. Vexillum. G–H. Wing. I–J. Keel petals. K. Androecium. L in A taxonomic revision of the South American genus Discolobium (Leguminosae, Papilionoideae)

FIGURE 6. Discolobium tocantinum Ducke. A. Branch with leaf and inflorescence. B. Leaflet. C. Bract. D. Bracteole. E. Calyx. F. Vexillum. G–H. Wing. I–J. Keel petals. K. Androecium. L. Gynoecium. (A–M from A. Ducke 16212 (RB))

opencc-zeroDec 2017View details →

Data from: Increased male bias in eider ducks can be explained by sex-specific survival of prime-age breeders

In contrast to theoretical predictions of even adult sex ratios, males are dominating in many bird populations. Such bias among adults may be critical to population growth and viability. Nevertheless, demographic mechanisms for biased adult sex ratios are still poorly understood. Here, we examined potential demographic mechanisms for the recent dramatic shift from a slight female bias among adult eider ducks (Somateria mollissima) to a male bias (about 65% males) in the Baltic Sea, where the species is currently declining. We analysed a nine-year dataset on offspring sex ratio at hatching based on molecularly sexed ducklings of individually known mothers. Moreover, using demographic data from long-term individual-based capture-recapture records, we investigated how sex-specific survival at different ages after fledgling can modify the adult sex ratio. More specifically, we constructed a stochastic two-sex matrix population model and simulated scenarios of different survival probabilities for males and females. We found that sex ratio at hatching was slightly female-biased (52.8%) and therefore unlikely to explain the observed male bias among adult birds. Our stochastic simulations with higher survival for males than for females revealed that despite a slight female bias at hatching, study populations shifted to a male-biased adult sex ratio (> 60% males) in a few decades. This shift that was driven by prime reproductive-age individuals (≥5-year-old), with sex-specific survival of younger age classes playing a minor role. Hence, different age classes contributed disproportionally to population dynamics. We argue that an alternative explanation for the observed male dominance among adults - sex-biased dispersal - can be considered redundant and is unlikely, given the ecology of the species. The present study highlights the importance of considering population structure and age-specific vital rates when assessing population dynamics and management targets.

opencc-zeroDec 2012View details →

Data from: Wintering sea duck distribution along the Atlantic coast of the United States

Although monitoring data for sea ducks (Tribe Mergini) are limited, current evidence suggests that four of the most common species wintering along the eastern coast of the United States—long-tailed duck Clangula hyemalis, white-winged scoter Melanitta fusca, surf scoter Melanitta perspicillata, and black scoter Melanitta americana—may be declining, while the status of American common eider Somateria mollissima dresseri is uncertain. The apparent negative trends, combined with the fact that sea duck life histories are among the most poorly documented of North American waterfowl, have led to concerns for these species and questions about the impacts of human activities, such as hunting, as well as catastrophic events and environmental change. During winter, thousands of sea ducks are found along the U.S. Atlantic coast, where they may be affected by proposed wind-power development, changes to marine traffic, aquaculture practices, sand mining, and other coastal development. Possible impacts are difficult to quantify because traditional winter waterfowl surveys do not cover many of the marine habitats used by sea ducks. Thus, the U.S. Fish and Wildlife Service conducted an experimental survey of sea ducks from 2008 to 2011 to characterize their winter distributions along the U.S. Atlantic coast. Each year, data were collected on 11 species of sea ducks on >200 transects, stretching from Maine to Florida. In this paper, we describe distribution of common eider, long-tailed duck, white-winged scoter, surf scoter, and black scoter. Densities of the two species with the most northerly distribution, white-winged scoter and common eider, were highest near Cape Cod and Nantucket. Long-tailed duck was most abundant around Cape Cod, Nantucket Shoals, and in Chesapeake Bay. Surf scoter also concentrated within Chesapeake Bay; however, they were additionally found in high densities in Delaware Bay, and along the Maryland–Delaware outer coast. Black scoter, the most widely distributed species, occurred at high densities along the South Carolina coast and the mouth of Chesapeake Bay. Spatial patterns of high-density transects were consistent among years for all species except black scoter, which exhibited the most interannual variation in distribution. The distance from land, depth, and bottom slope where flocks were observed varied among species and regions, with a median distance of 3.8 km from land along the coastal transects and 75% of flocks observed over depths of <16 m. Common eider and long-tailed duck were observed closer to shore and over steeper ocean bottoms than were the three scoter species. Our results represent the first large-scale quantitative description of winter sea duck distribution along the U.S. Atlantic coast, and should guide the development of sea duck monitoring programs and aid the assessment of potential impacts of ongoing and proposed offshore development.

opencc-zeroDec 2011View details →

Data from: Stepwise colonization of the Andes by Ruddy Ducks and the evolution of novel β-globin variants

Andean uplift played a key role in Neotropical bird diversification, yet past dispersal and genetic adaptation to high-altitude environments remain little understood. Here we use multilocus population genetics to study population history and historical demographic processes in the ruddy duck (Oxyura jamaicensis), a stiff-tailed diving duck comprising three subspecies distributed from Canada to Tierra del Fuego and inhabiting wetlands from sea level to 4500 m in the Andes. We sequenced the mitochondrial DNA, four autosomal introns and three haemoglobin genes (αA, αD, βA) and used isolation-with-migration (IM) models to study gene flow between North America and South America, and between the tropical and southern Andes. Our analyses indicated that ruddy ducks dispersed first from North America to the tropical Andes, then from the tropical Andes to the southern Andes. While no nonsynonymous substitutions were found in either α globin gene, three amino acid substitutions were observed in the βA globin. Based on phylogenetic reconstruction and power analysis, the first βA substitution, found in all Andean individuals, was acquired when ruddy ducks dispersed from low altitude in North America to high altitude in the tropical Andes, whereas the two additional substitutions occurred more recently, when ruddy ducks dispersed from high altitude in the tropical Andes to low altitude in the southern Andes. This stepwise colonization pattern accompanied by polarized βA globin amino acid replacements suggest that ruddy ducks first acclimatized or adapted to the Andean highlands and then again to the lowlands. In addition, ruddy ducks colonized the Andean highlands via a less common route as compared to other waterbird species that colonized the Andes northwards from the southern cone of South America.

opencc-zeroOct 2019View details →

Persistence of an endangered native duck, feral mallards, and multiple hybrid swarms across the main Hawaiian Islands

Interspecific hybridization is recognized as an important process in the evolutionary dynamics of both speciation and the reversal of speciation. However, our understanding of the spatial and temporal patterns of hybridization that erode versus promote species boundaries is incomplete. The endangered, endemic koloa maoli (or Hawaiian duck, Anas wyvilliana) is thought to be threatened with genetic extinction through ongoing hybridization with an introduced congener, the feral mallard (A. platyrhynchos). We investigated spatial and temporal variation in hybrid prevalence in populations throughout the main Hawaiian Islands, using genomic data to characterize population structure of koloa, quantify the extent of hybridization, and compare hybrid proportions over time. To accomplish this, we genotyped 3,308 double-digest restriction-site-associated DNA (ddRAD) loci in 425 putative koloa, mallards, and hybrids from populations across the main Hawaiian Islands. We found that despite a population decline in the last century, koloa genetic diversity is high. There were few hybrids on the island of Kauaʻi, home to the largest population of koloa. By contrast, we report that sampled populations outside of Kauaʻi can now be characterized as hybrid swarms, in that all individuals sampled were of mixed koloa × mallard ancestry. Further, there is some evidence that these swarms are stable over time. These findings demonstrate spatial variation in the extent and consequences of interspecific hybridization, and highlight how islands or island-like systems with small population sizes may be especially prone to genetic extinction when met with a congener that is not reproductively isolated.

opencc-zeroDec 2016View details →

Data from: Identifying demographic and environmental drivers of recruitment and population growth in a cavity nesting sea duck population

Traits with the greatest proportional effects on fitness are typically conserved (Stearns 1992), and traits with larger temporal variation frequently play a dominant role in population dynamics (Cooch et al. 2001). We examined recruitment patterns and population growth in Common Goldeneyes (Bucephala clangula; hereafter goldeneye), using Pradel mark-recapture models from a long-term nest box study (1997-2010). Our objectives were to estimate recruitment (f) and population growth (λ) relative to recruitment origin group (in-situ or unknown), investigate environmental and density dependent effects on these parameters, and evaluate potential immigration patterns. We detected group-specific differences for f (in-situ: 0.47± 0.13 SE, unknown: 0.31 ± 0.04), and the proportion of boxes occupied by goldeneyes the year prior to recruitment had a significant negative effect on recruitment for the in-situ group (β = -1.04; 85% CI -1.29, -0.78), and a positive effect for the unknown group (β = 0.45; 85% CI 0.30, 0.61). The negative box occupancy effect in the year prior to recruitment, when in-situ yearling goldeneyes prospect for potential nest sites, suggests that local nesting densities may limit recruitment of locally hatched females. We identified two competitive models for λ, which averaged 1.04 ± 0.03 and included interactions between recruitment origin group and a linear temporal trend, and the proportion of ducklings marked two years prior. By evaluating all levels of marking effort on λ, we determined that even if all hatched ducklings were marked in a given year, the resulting in-situ λ was consistently lower than all observed population-level λs during the study, indicating that individuals produced outside of study area nest boxes contributed to λ. Though female goldeneyes are considered highly philopatric, our results suggest that female natal and breeding dispersal may be more prevalent than previously thought, and the spatial scale at which these processes occur requires further investigation.

FIGURES 18–25. Macrogynoplax poranga, Male. 18. Sterna 7-10 in Description of one new species and a key to adults of Macrogynoplax Enderlein (Plecoptera, Perlidae) from Reserva Florestal Adolpho Ducke, Amazonas, Brazil

FIGURES 18–25. Macrogynoplax poranga, Male. 18. Sterna 7-10; 19. Terga 9-10; 20. Hammer, ventral. 21. Hammer, lateral; 22. Paraproct, lateral; 23. Aedeagus, dorsal; 24. Aedeagus, ventral; 25. Aedeagus, lateral.

FIGURES 35–43 in Description of one new species and a key to adults of Macrogynoplax Enderlein (Plecoptera, Perlidae) from Reserva Florestal Adolpho Ducke, Amazonas, Brazil

FIGURES 35–43. Macrogynoplax anae sp.n., male. 35. Sterna 7-10; 36. Terga 9-10; 37. Hammer, ventral; 38. Hammer, lateral; 39. Paraproct, lateral; 40. Aedeagus, dorsal; 41. Aedeagus, ventral; 42. Aedeagus, lateral; 43. Aedeagus, caudal.

FIGURES 9–17 in Description of one new species and a key to adults of Macrogynoplax Enderlein (Plecoptera, Perlidae) from Reserva Florestal Adolpho Ducke, Amazonas, Brazil

FIGURES 9–17. Macrogynoplax delicata; 9. Male, Sterna 7-10,ventral; 10. Male, Terga 9-10 dorsal; 11-12. Male hammer, ventral and lateral; 13. Male, paraproct lateral; 14. Male, aedeagus, dorsal; 15. Male, aedeagus, ventral; 16. Male, aedeagus, lateral; 17. Female, sterna 8-10

FIGURES 1–8. 1 in Description of one new species and a key to adults of Macrogynoplax Enderlein (Plecoptera, Perlidae) from Reserva Florestal Adolpho Ducke, Amazonas, Brazil

FIGURES 1–8. 1. Macrogynoplax delicata, male habitus (in alcohol); 2–3 M. pulchra. 2. Male habitus (in life); 3. Female habitus (in life); 4. Head and pronotum of M. delicata; 5. Fore– and hindwings of M. delicata; 6. Fore– and hindwings of M. poranga; 7. Fore– and hindwings of M. pulchra; 8. Fore– and hindwings of M. anae.

FIGURES 26–34. Macrogynoplax pulchra. 26. Male, sterna 7-10 in Description of one new species and a key to adults of Macrogynoplax Enderlein (Plecoptera, Perlidae) from Reserva Florestal Adolpho Ducke, Amazonas, Brazil

FIGURES 26–34. Macrogynoplax pulchra. 26. Male, sterna 7-10; 27. Male terga 9-10; 28. Male, hammer, ventral; 29. Male, hammer, lateral; 30. Paraproct, lateral; 31. Aedeagus, dorsal; 32. Aedeagus, ventral; 33. Aedeagus, lateral; 34. Female, sterna 8-10 (original drawing of Ribeiro-Ferreira and Froehlich 1999).