Oxyura Research Articles

Morphologically Adaptive Crash Landing on a Wall: Soft‐Bodied Models of Gliding Geckos with Varying Material Stiffnesses

Landing on vertical surfaces in challenging environments is a critical ability for multimodal robots—it allows the robot to hold position above the ground without expending energy to hover. Asian flat‐tailed geckos (Hemidactylus platyurus) are observed to glide and perch on vertical surfaces by relying on their tail and body morphology, potentially reducing the control effort to perch. This novel perching mechanism using a bioinspired physical model is discussed and its tail and body parameters to determine their influence on perching success and the kinematics of the gecko's dynamic landing maneuver are adjusted. Perching performance is evaluated by changing the model's torso and tail stiffness. Combining a compliant torso and stiff tail enables the model to passively perch on a vertical substrate with a success rate >90%, compared with ≈10% without a tail attached. A compliant torso is necessary to absorb the in‐flight kinetic energy and accommodate the uncertainties in approach conditions. Similar to the gecko's perching strategy, the stiff tail pushes against the substrate, preventing the model from falling backward head over heels. These findings highlight the critical role of tail and material stiffness for perching and provide a simplified mechanism to impart perching capabilities in robots.

Time-activity budgets of stiff-tailed ducks in Puerto Rico

Habitat loss and degradation have contributed to declining populations of stiff-tailed ducks including the migratory northern ruddy duck (Oxyura jamaicensis rubida), and non-migratory masked duck (Nomonyx dominicus) and West Indian ruddy duck (Oxyura j. jamaicensis). Studies collecting time-activity budgets on waterfowl can provide important insight into habitat use, behavior, and niche partitioning. Even though the northern ruddy duck and West Indian ruddy duck are recognized as the same species, we treated them separately to appraise possible ecological differences. We recorded 24-h time-activity budgets for masked ducks (n = 142), northern ruddy ducks (n = 1,401), and West Indian ruddy ducks (n = 3,765) on the Laguna Cartagena National Wildlife Refuge in Lajas, Puerto Rico from January through April 2015 and 2016. Behaviors varied among taxa, between sexes, and between diurnal and nocturnal sampling periods. Resting and sleeping were common behaviors observed during the day and night, but all 3 taxa fed more at night with masked duck feeding more than the West Indian ruddy duck and northern ruddy duck. Northern ruddy duck and West Indian ruddy duck time-activity budgets varied with 7 of 8 behavioral categories during the day and 5 of 8 behavioral categories at night differing. Ecological differences such as body size and migration of northern ruddy ducks may account for the differences in behavior when compared to non-migratory West Indian ruddy ducks.

New skeletal material sheds light on the palaeobiology of the Pleistocene marsupial carnivore, Thylacoleo carnifex.

The extinct marsupial ‘lion’ Thylacoleo carnifex was Australia’s largest mammalian carnivore. Despite being the topic of more discussion than any other extinct Australian marsupial (excepting perhaps the Thylacine), basic aspects of its palaeobiology, including its locomotory repertoire, remain poorly understood. Recent discoveries allowed the first reconstruction of an entire skeleton including the first complete tail and hitherto-unrecognised clavicles. Here we describe these elements and re-assess the biomechanics of the postcranial skeleton via comparisons with a range of extant terrestrial, scansorial and arboreal Australian marsupials. Our analysis suggests that T. carnifex possessed: a relatively stiff tail comprising half of the vertebral column length; proximal caudal centra exhibiting a relatively high resistance to sagittal and lateral bending (RSB and RTB); relatively enlarged areas of origin for caudal flexors and extensors; a rigid lumbar spine; and a shoulder girdle braced by strong clavicles. The lever arms of major muscle/tendon systems controlling the axial and appendicular skeleton were identified and RSB and RTB calculated. The combination of these features compared most closely overall with those of the much smaller Tasmanian Devil (Sarcophilus harrisii), a hunter/scavenger capable of climbing. Similar locomotor behaviour is proposed for Thylacoleo carnifex. Orientation of articular facets and RSB stresses also indicate that T. carnifex may have held its tail in a dorsally-flexed position.

Diurnal and Nocturnal Dive Durations and Inter-Dive Intervals of Stiff-Tailed Ducks in Puerto Rico

Research comparing dive durations and inter-dive intervals of stiff-tailed diving ducks, which is important for understanding differences in species ecology, is lacking for the non-migratory Masked Duck (Nomonyx dominicus) and West Indian Ruddy Duck (Oxyura jamaicensis jamaicensis), and the migratory Northern Ruddy Duck (Oxyura jamaicensis jamaicensis). Although the Northern Ruddy Duck and West Indian Ruddy Duck are considered the same species, we treated them separately to evaluate possible ecological differences. All three were observed at the same time in the same place in Laguna Cartagena National Wildlife Refuge, Puerto Rico. Dive durations and inter-dive intervals were recorded for Masked Duck (n = 60), Northern Ruddy Duck (n = 70), and West Indian Ruddy Duck (n = 445) from 1 January through 30 April 2015 and 2016. The Northern Ruddy Duck had a longer mean (± SE) dive duration (22.9 ± 0.75 sec) than the West Indian Ruddy Duck (18.8 ± 0.02 sec). Northern Ruddy Ducks likely had longer dive times because of their larger body size and migratory behavior.

Oxyura vittata (Philippi, 1860) (Aves, Anatidae): range extension and first record from the Upper Paraguay basin, Brazil

Oxyura vittata (Philippi, 1860) (Aves, Anatidae): range extension and first record from the Upper Paraguay basin, Brazil

Microtus agrestis (Rodentia: Cricetidae)

Microtus agrestis (Linnaeus, 1761) is a relatively small microtine rodent commonly called the field vole. It has a compact body, blunt oval head, short round ears that barely protrude from the fur, and a short, bicolored, rather stiff tail. It is easily confused with sympatric or parapatric Microtus arvalis, M. oeconomus, and M. levis (M. rossiaermeridonalis) with indistinguishable juveniles. There is geographical variation of size and coloration ranging across Europe south from the Pyrenees to the Arctic coast and Alps eastward to the River Yenisei and Lake Baikal in Asia up to elevations of 2,100 m. It prefers wet meadow areas, riverside habitats, and forests with dense herbaceous cover. M. agrestis is considered to represent a trace of a 1st radiation of the genus Microtus in Europe.

Soft-Legged Wheel-Based Robot with Terrestrial Locomotion Abilities

In recent years robotics has been influenced by a new approach, soft-robotics, bringing the idea that safe interaction with user and more adaptation to the environment can be achieved by exploiting easily deformable materials and flexible components in the structure of robots. In 2016, the soft-robotics community has promoted a new robotics challenge, named RoboSoft Grand Challenge, with the aim of bringing together different opinions on the usefulness and applicability of softness and compliancy in robotics. In this paper we describe the design and implementation of a terrestrial robot based on two soft legged wheels. The tasks predefined by the challenge were set as targets in the robot design, which finally succeeded to accomplish all the tasks. The wheels of the robot can passively climb over stairs and adapt to slippery grounds using two soft legs embedded in their structure. The soft legs, fabricated by integration of soft and rigid materials and mounted on the circumference of a conventional wheel, succeed to enhance its functionality and easily adapt to unknown grounds. The robot has a semi stiff tail that helps in the stabilization and climbing of stairs. An active wheel is embedded at the extremity of the tail in order to increase the robot maneuverability in narrow environments. Moreover two parallelogram linkages let the robot to reconfigure and shrink its size allowing entering inside gates smaller than its initial dimensions.

New species of Parapharyngodon (Nematoda: Pharyngodonidae) in Phymaturus spp. (Iguania: Liolaemidae) from Argentina.

Parapharyngodon sanjuanensis sp. nov. (Nematoda: Pharyngodonidae) from the large intestines of Phymaturus punae and Phymaturus williamsi (Squamata: Liolaemidae) from province of San Juan, Argentina, is described and illustrated. Parapharyngodon sanjuanensis sp. nov. is the 54th species assigned to the genus and the 8th from the Neotropical region. It differs from other species in the genus in that males possess 8 caudal papillae, 6 of which are large and pedunculate, 2 are small, almost inconspicuous; anterior lip echinate, posterior lip bilobate; females possess prominent vulva and short stiff tail spike.

The rise of birds: 225 million years of evolution

Dinosaurs have become so popular that their flying relatives are often neglected, even though they are still among us. Birds, the living are successful vertebrates which have evolved, adapted and survived over a period of 225 million years. This text is a detailed, illustrated review of the fossil record of birds in a modern context. Palaeontologist, Chatterjee, provides a chronology documenting the long odyssey of birds since Protoavis - which may have taken to the air some 75 million years before the widely known first bird, Archaeopterix. Throughout the text, the author offers details from the history of birds past and present, including: some intelligent theropods such as dromaeosaurs were arboreal and could climb trees with their swivel wrist joint and stiff tail, and glide from tree to ground; the discovery of downy theropod dinosaurs from China indicates that upper jaw mobility, not feathers, is the most distinctive characteristic of birds; and most birds were wiped out 65 million years ago, along with dinosaurs, by large meteoritic impacts. However, a few lineages of birds rebounded from this catastrophe and underwent an explosive evolution. The volume also discussed the significance of the many recently discovered bird and possible bird fossils, from Europe to China to Latin America. Chatterjee outlines varying theories of how animal flight developed and explains, in terms of comparative anatomy, what makes a bird a bird. The book covers some of the greatest events in avian development: their emergence in the Triassic pangean world; their flight refinement and global diversification during the continental breakup of the Jurassic and Cretaceous periods; their sudden decline at the end-Cretaceous extinction; their rebound and explosive radiation during the Cenozoic era; and finally their destiny with us.

TÉTANO EM OVINOS APÓS CASTRAÇÃO COM LIGADURA DE BORRACHA

Tetanus is of high importance for animal production. Clostridium tetani is an anaerobic and gram-positive bacillus and it is most commonly caused by a contaminated wound. This study reports a case of tetanus in 6-month-old sheep raised in Coremas, Paraiba, Brazil. A total of 11 lambs were submitted to castration with a rubber band. Four animals died and one was taken to the Veterinary Hospital at Universidade Federal de Campina Grande. The animal presented congestion of mucous membranes, tachycardia, dyspnea, staggering gait, muscular tremors, squint, limb spasms, erect ears, stiff tail, sensitivity to sonorous stimuli, mandibular spasms, and nystagmus. Based on the epidemic data, clinical analysis, and absence of pathological changes, the diagnosis of tetanus was established. We conclude that good hygiene and disinfection of wounds and surgical area are essential before castration procedures in order to minimize the chance of infection.

Life history of a basal bird: morphometrics of the Early Cretaceous Confuciusornis

Confuciusornis sanctus stands out among the remarkable diversity of Mesozoic birds recently unearthed from China. Not only is this primitive beaked pygostylian (birds with abbreviated caudal vertebrae fused into a pygostyle) much more abundant than other avian taxa of this age but differences in plumage between specimens--some having a pair of long stiff tail feathers--have been interpreted as evidence for the earliest example of sexual dimorphism in birds. We report the results of a multivariate morphometric study involving measurements of more than 100 skeletons of C. sanctus. Our analyses do not show any correlation between size distribution and the presence or absence of blade-like rectrices (tail feathers), thus implying, that if these feathers are sexual characters, they are not correlated with sexual size dimorphism. Our results also provide insights into the taxonomy and life history of confuciusornithids, suggesting that these birds may have retained ancestral dinosaurian growth patterns characterized by a midlife exponential growth stage.

Espécies de tripes (Insecta, Thysanoptera) habitantes da vegetação do Parque Estadual de Itapuã, Viamão, Rio Grande do Sul, Brasil

This study is a contribution to the knowledge of the thysanopterofauna of southern Brazil. From June 2003 to April 2004, seasonal field trips were conducted at the Parque Estadual de Itapua (50o50’-51o05’W and 30o20’-30o27’S), in the county of Viamao, Rio Grande do Sul, to collect shoots with/without flowers of various plant species. The material was brought to the laboratory where the thrips were sorted. A total of 23 thrips species belonging to 15 genera and two families were obtained. Nine of the species resulted as new record for Rio Grande do Sul (*), and other two also for Brazil (**). The species sampled are as follows: Aneristothrips claripennis (Moulton, 1933)*, Aurantothrips orchidearum (Bondar, 1931)*, Ceratothripoides lagoenacollus (Moulton, 1933)*, Chaetanaphothrips orchidii (Moulton, 1907)*, Chaetisothrips striatus (Hood, 1935), Coremothrips pallidus Hood, 1925*, Craniothrips urichi Bagnall, 1915, Frankliniella bertelsi (De Santis, 1967), Frankliniella distinguenda Bagnall*, 1919, Frankliniella gardeniae Moulton, 1948*, Frankliniella gemina Bagnall, 1919, Frankliniella insularis (Franklin, 1908), Frankliniella oxyura Bagnall, 1919*, Frankliniella rodeos Moulton, 1933, Haplothrips fiebrigi Priesner, 1931, Hoodothrips lineatus (Hood, 1928), Microcephalothrips abdominalis (Crawford, 1910), Neohydatothrips denigratus (De Santis, 1966)**, Neohydatothrips fasciatus (Moulton, 1938)*, Neohydatothrips flavens (Moulton, 1941), Paraleucothrips minusculus Johansen, 1983**, Smicrothrips particula Hood, 1952, Thrips australis (Bagnall, 1915).

Is Homoplasy or Lineage Sorting the Source of Incongruent mtDNA and Nuclear Gene Trees in the Stiff-Tailed Ducks (Nomonyx-Oxyura)?

We evaluated the potential effects of homoplasy, ancestral polymorphism, and hybridization as obstacles to resolving phylogenetic relationships within Nomonyx-Oxyura stiff-tailed ducks (Oxyurinae; subtribe Oxyurina). Mitochondrial DNA (mtDNA) control region sequences from 94 individuals supported monophyly of mtDNA haplotypes for each of the six species and provided no evidence of extant incomplete lineage sorting or inter-specific hybridization. The ruddy ducks (O. j. jamaicensis,O. j. andina, O. j. ferruginea) are each others' closest relatives, but the lack of shared haplotypes between O. j. jamaicensis and O. j. ferruginea suggests long-standing historical isolation. In contrast, O. j. andina shares haplotypes with O. j. jamaicensis and O. j. ferruginea, which supports Todd's (1979) and Fjeldså's (1986) hypothesis that O. j. andina is an intergrade or hybrid subspecies of O. j. jamaicensis and O. j. ferruginea. Control region data and a much larger data set composed of approximately 8800 base pairs of mitochondrial and nuclear sequence for each species indicate that the two New World species, O. vittata and O. jamaicensis, branch basally within Oxyura. A clade of three Old World species (O. australis, O. maccoa, O. leucocephala) is well supported, but different loci and also different characters within the mtDNA data support three different resolutions of the Old World clade, yielding an essentially unresolved trichotomy. Fundamentally different factors limited the resolution of the mtDNA and nuclear gene trees. Gene trees for most nuclear loci were unresolved due to slow rates of mutation and a lack of informative variation, whereas uncertain resolution of the mtDNA gene tree was due to homoplasy. Within the mtDNA, approximately equal numbers of characters supported each of three possible resolutions. Parametric and nonparametric bootstrap analyses suggest that resolution of the mtDNA tree based on ~4300 bp per taxon is uncertain but that complete mtDNA sequences would yield a fully resolved gene tree. A short internode separating O. leucocephala from (O. australis, O. maccoa) in the best mtDNA tree combined with long terminal branches and substantial rate variation among nucleotide sites allowed the small number of changes occurring on the internode to be obscured by homoplasy in a significant portion of simulated data sets. Although most nuclear loci were uninformative, two loci supported a resolution of the Old World clade (O. maccoa, O. leucocephala) that is incongruent with the best mtDNA tree. Thus, incongruence between nuclear and mtDNA trees may be due to random sorting of ancestral lineages during the short internode, homoplasy in the mtDNA data, or both. The Oxyura trichotomy represents a difficult though likely common problem in molecular systematics. Given a short internode, the mtDNA tree has a greater chance of being congruent with the history of speciation because its effective population size (N(e)) is one-quarter that of any nuclear locus, but its resolution is more likely to be obscured by homoplasy. In contrast, gene trees for more slowly evolving nuclear loci will be difficult to resolve due to a lack of substitutions during the internode, and when resolved are more likely to be incongruent with the species history due to the stochastic effects of lineage sorting. We suggest that researchers consider first whether independent gene trees are adequately resolved and then whether those trees are congruent with the species history. In the case of Oxyura, the answer to both questions may be no. Complete mtDNA sequences combined with data from a very large number of nuclear loci may be the only way to resolve such trichotomies.

Wing and Tail Molts of the Ruddy Duck

Stiff-tailed ducks (Oxyurini) are reputed to be unique among waterfowl in having two complete wing and tail molts annually. We examined molt patterns in wild Ruddy Ducks (Oxyura jamaicensis) and in captives of known age. Adults of both groups underwent a complete wing molt in early autumn. A spring wing molt was very rare in wild Ruddy Ducks, but occurred more often in captives, especially in adult females. Ruddy Ducks replace rectrices twice annually. These molts are complete but unusual in that feathers are typically replaced in two waves, in which (1) every other rectrix is lost and largely re-grown before (2) the intervening feathers are molted. As a result, the molt is protracted and the tail plumage, at times, includes feathers of two generations. The pattern ensures that a functional tail is maintained at all times.

Clonidine modulates BAY K 8644-induced rat behavior and neurotransmitter changes in the brain

BAY K 8644 (methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4[2-trifluoromethyl-phenyl]-pyridine-5-carboxylate), an activator of dihydropyridine-sensitive Ca 2+ channels, injected in rats [2 mg/kg intraperitoneally (i.p.)], induces behavioral changes including ataxia, increased sensitivity to auditory stimulation, stiff tail, arched back, limb tonus and clonus, and rolling over. Neurochemical changes in the brain 45 min after application of 2 mg/kg were characterized by a significant decrease of noradrenaline in the amygdala (−27.8%, P<0.02) and piriform cortex (−16.3%, P<0.02). No significant changes of catecholamines were found in the hippocampal subregions CA1, CA3 and dentate gyrus or in the septum as compared to controls. The dopamine metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), in the amygdala were elevated by 60% ( P<0.02) and 66.7% ( P<0.02), respectively. In the septum, a 52.6% ( P<0.02) increase of HVA was observed. Analysis of amino acids revealed a marked increase of γ-aminobutyric acid (GABA) content (+50.4%, P<0.001) in the septum. Pretreatment of the rats with the α 2-adrenoceptor agonist, clonidine (0.1 mg/kg i.p.), 30 min before BAY K 8644 (2 mg/kg i.p.) injection completely abolished the behavioral and neurochemical changes. The data suggest that the Ca 2+-dependent neurotransmitter release provoked by BAY K 8644 can be modulated by stimulation of presynaptic α 2-adrenoceptors. The effect of clonidine on the GABAergic system may represent an important mechanism involved in the prevention of BAY K 8644-induced behavior.

Bromocontryphan: post-translational bromination of tryptophan.

We demonstrate that post-translational bromination of a tryptophan residue occurs in the biologically active octapeptide bromocontryphan, purified and characterized from Conus radiatus venom. Clones encoding bromocontryphan were identified from a cDNA library made from C. radiatus venom ducts. The mRNA sequence obtained predicts a prepropeptide which has the mature peptide sequence at the C-terminal end, with the L-6-bromotryptophan residue encoded by UGG, the Trp codon. These data provide the first direct evidence for post-translational bromination of a polypeptide which is translated through the normal cellular machinery. In addition to bromination, the peptide, which induces a "stiff tail" syndrome in mice, has several other modifications as shown by the sequence [Formula: See Text] in which Hyp = hydroxyproline. Asterisks indicate post-translational modifications (left to right): proteolytic cleavage at the N-terminus; hydroxylation of Pro3; epimerization of Trp4; bromination of Trp7, and C-terminal amidation. Bromocontryphan appears to have the highest density of post-translational modifications known among gene-encoded polypeptides. The overall result is a molecule which closely resembles marine natural products produced through specialized biosynthetic pathways comprising many enzyme-catalyzed steps.

Spauligodon gehyrae n. sp. (Nematoda: Pharyngodonidae) from Gehyra oceanica (Sauria: Gekkonidae) from Guam, Mariana Islands, Micronesia

Spauligodon gehyrae n. sp. (Nematoda: Pharyngodonidae), a new oxyurid nematode, discovered in the large intestine of the gecko Gehyra oceanica is described and illustrated. Nine of 11 adult female specimens of G. oceanica collected on Guam, Mariana Islands, Micronesia, harbored a total of 480 specimens of S. gehyrae; prevalence of infection was 82% (mean intensity 53, range 6-179). Spauligodon gehyrae represents the 33rd species to be described for this genus and is distinguished by the presence of truncated egg ends, the short stiff tail spike of the female, and the presence of a spicule in the male. This is the second species of Spauligodon to be described from Oceania.

Dopamine-derived endogenous 1( R),2( N)-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, N-methyl-( R)-salsolinol, induced parkinsonism in rat: biochemical, pathological and behavioral studies

Dopamine-derived 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (salsolinol, Sal) and related compounds were examined for their selective neurotoxicity to dopamine neurons by injection into the rat striatum. Among salsolinol analogs examined, only N-methyl-( R)-salsolinol (NM( R)Sal) induced behavioral changes very similar to those in Parkinson's disease: hypokinesia, stiff tail, limb twitching at rest and postural abnormality. Biochemical analysis showed that after NM( R)Sal injection, NM( R)Sal itself and its oxidation product, 1,2-dimethyl-6,7-dihydroxyisoquinolinium ion (DMDHIQ +) accumulated in the striatum, and also in the substantia nigra definite amount of DMDHIQ + was detected. Dopamine and noradrenaline were reduced in the striatum and more markedly in the substantia nigra, whereas serotonin and its metabolite were not affected. Morphological analysis revealed selective reduction of tyrosine hydroxylase (TH)-containing neurons in the substantia nigra after continuous NM( R)Sal administration in the striatum. These results demonstrate the selective cytotoxicity of NM( R)Sal to the dopamine neurons in the substantia nigra, and the possible involvement of this 6,7-dihydroxyisoquinoline in the pathogenesis of Parkinson's disease is discussed.

Technical note: ultrasound guided transvaginal drainage utilizing a 7 French pig tail balloon catheter.

Ultrasound guided transvaginal drainage of abscesses in the small pelvis is usually performed using needles or stiff pig tail catheters without internal fixation. To prevent dislodgement during the subsequent drainage and irrigation procedure, we have developed a new soft 7 F balloon catheter for continuous transvaginal drainage. The catheter is made of soft C-flex and contains two channels, one for drainage and one for inflating a small distal balloon (outer diameter, 10 mm).

Waterfowl Use of the Laurentian Great Lakes

Literature on habitat and limiting factors of waterfowl in Great Lakes wetlands and deep water habitats is reviewed; more than 30 species of waterfowl use coastal habitats at some time during the year. Waterfowl use of the Great Lakes has declined dramatically from presettlement times; the obvious cause is human encroachment on coastal wetlands and destruction of river delta and embayed wetland complexes. Loss of wetland habitats from diking and filling above the average water level constitutes a permanent habitat loss, especially during high water cycles. The greatest number of species and individuals use 15 concentration areas during the spring and fall migratory periods when use by diving ducks, sea and stiff tailed ducks, and swans and geese predominates. Lesser numbers of species use the coastal wetlands for breeding. Large concentrations of dabbling ducks, primarily mallards ( Anas platyrhynchos) and American black ducks ( A. rubripes), and mergansers ( Mergus spp.) are found on ice-free areas during winter. Wetland habitats have become more favorable, due to human modifications, to dabbling duck species found in the prairie habitats of North America. Mallards have become the most numerous species breeding in coastal wetlands along with a concomitant decline in black ducks, which may be a consequence of introgression. Habitat modifications, degradation, and loss have great potential to affect existing waterfowl populations negatively and to point the way toward future research.