131,423 research outputs found
Ruddy Shelduck Tadorna ferruginea home range and habitat use during the non-breeding season in Assam, India
No full textIndia is an important non-breeding ground for migratory waterfowl in the Central Asian Flyway. Millions of birds visit wedands across the country, yet information on their distribution, abundance, and use of resources is rudimentary at best. Limited information suggests that populations of several species of migratory ducks are declining due to encroachment of wedand habitats largely by agriculture and industry. The development of conservation strategies is stymied by a lack of ecological information on these species. We conducted a preliminary assessment of the home range and habitat use of Ruddy Shelduck Tadornaferruginea in the northeast Indian state of Assam. Seven Ruddy Shelducks were fitted with solar-powered Global Positioning System (GPS) satellite transmitters, and were tracked on a daily basis during the winter of 2009-2010. Locations from all seven were used to describe habitat use, while locations from four were used to quantify their home range, as the other three had too few locations (<30) for home range estimation. A Brownian Bridge Movement Model (BBMM), used to estimate home ranges, found that the Ruddy Shelduck had an average core use area (i.e. the contour defining 50% of positions) of 40 km 2 (range = 22-87 km2) and an average home range (95% contour) of 610 km2 (range = 222-1,550 km2). Resource Selection Functions (RSF), used to describe habitat use, showed that the birds frequented riverine wetlands more than expected, occurred on grasslands and shrublands in proportion to their availability, and avoided woods and cropland habitats. The core use areas for three individuals (75%) were on the Brahmaputra River, indicating their preference for riverine habitats. Management and protection of riverine habitats and nearby grasslands may benefit conservation efforts for the Ruddy Shelduck and waterfowl species that share these habitats during the non-breeding seaso
High altitude flights by ruddy shelduck Tadorna ferruginea during trans-Himalayan migrations
No full textThis is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Birds that migrate across high altitude mountain ranges are faced with the challenge of maintaining vigorous exercise in environments with limited oxygen. Ruddy shelducks are known to use wintering grounds south of the Tibetan Plateau at sea level and breeding grounds north of Himalayan mountain range. Therefore, it is likely these shelducks are preforming high altitude migrations. In this study we analyse satellite telemetry data collected from 15 ruddy shelduck from two populations wintering south of the Tibetan Plateau from 2007 to 2011. During north and south migrations ruddy shelduck travelled 1481 km (range 548–2671 km) and 1238 km (range 548–2689 km) respectively. We find mean maximum altitudes of birds in flight reached 5590 m (range of means 4755–6800 m) and mean maximum climb rates of 0.45 m s –1 (range 0.23–0.74 m s –1 ). The ruddy shelduck is therefore an extreme high altitude migrant that has likely evolved a range of physiological adaptations in order to complete their migrations
Traumatic encounter between Ruddy Turnstone Arenaria interpres and Hermit Crab Coenobita perlatus at D’Arros Island, Amirantes Group, Seychelles
No full textOn 13 March 2011 at 09:00, we encountered a juvenile Ruddy Turnstone Arenaria interpres on the ground in apparent distress. We were conducting a nesting sea turtle track count survey along the sandy shoreline of D’Arros Island in the Amirantes Group of the Seychelles. Unable to take flight, the Turnstone was struggling in the manner of a bird entangled by the sticky seeds of the Pisonia grandis tree. But, upon closer inspection we found that the tip of its bill was in the grip of th left claw of a Hermit Crab Coenobita perlatus
Hybridization between white-headed ducks and introduced ruddy ducks in Spain
No full textThe ruddy duck,
Oxyura jamaicensis
, was introduced to Great Britain in the mid-20th
century and has recently spread to other Western European countries. In Spain, ruddy
ducks hybridize with the globally endangered white-headed duck,
Oxyura leucocephala
.
We assessed the effects of hybridization on the Spanish white-headed ducks, which
constitute 25% of the global population of this species, using a panel of eight nuclear intron
markers, 10 microsatellite loci, and mtDNA control region sequences. These data allowed
parental individuals, F
1
hybrids, and the progeny of backcrossing to be reliably distinguished.
We show that hybrids between the two species are fertile and produce viable offspring in
backcrosses with both parental species. To date, however, we found no extensive introgression
of ruddy duck genes into the Spanish white-headed duck population, probably due to the
early implementation of an effective ruddy duck and hybrid control programme. We also
show that genetic diversity in the expanding European ruddy duck population, which was
founded by just seven individuals, exceeds that of the native Spanish white-headed duck
population, which recently recovered from a severe bottleneck. Unless effective control of
ruddy ducks is continued, genetic introgression will compromise the unique behavioural
and ecological adaptations of white-headed ducks and consequently their survival as a
genetically and evolutionary distinct species.Peer reviewe
The ruddy duck Oxyura jamaicensis in Europe: natural colonization or human introduction?
No full textNative to North America, ruddy ducks
Oxyura jamaicensis
now occur in 21 countries in the
western Palaearctic (including Iceland) and their expanding population threatens the
native white-headed duck,
Oxyura leucocephala
, through hybridization and possibly
competition for food and nest sites. We used mitochondrial DNA sequences and nuclear
microsatellites to test whether the European ruddy duck population is descended solely
from the captive population in the UK, which traces to seven individuals imported from the
USA in 1948, or, alternatively, has been augmented by natural dispersal of birds from North
America. Limited genetic diversity in the European population is consistent with a founder
population as small as seven birds. In addition, shifts in allele frequencies at several loci,
presumably due to genetic drift in the founding population, result in significant differentiation
between the European and North American populations. Despite the recent separation
of these populations, almost all individuals could be unambiguously assigned based on
their composite genotypes, to one of two distinct populations, one comprising all of the
European ruddy ducks we sampled (including those from Iceland and captive birds in
the UK) and the other comprising all North American samples. Our results confirm that
the European ruddy duck population is likely to derive solely from the captive population
in the UK and we find no evidence of recent arrivals from North America or of admixture
between ruddy ducks from Europe and North America.Peer reviewe
The ruddy duck Oxyura jamaicensis in Europe : natural colonization or human introduction?
No full textNative to North America, ruddy ducks Oxyura jamaicensis now occur in 21 countries in the western Palaearctic (including Iceland) and their expanding population threatens the native white-headed duck, Oxyura leucocephala, through hybridization and possibly competition for food and nest sites. We used mitochondrial DNA sequences and nuclear microsatellites to test whether the European ruddy duck population is descended solely from the captive population in the UK, which traces to seven individuals imported from the USA in 1948, or, alternatively, has been augmented by natural dispersal of birds from North America. Limited genetic diversity in the European population is consistent with a founder population as small as seven birds. In addition, shifts in allele frequencies at several loci, presumably due to genetic drift in the founding population, result in significant differentiation between the European and North American populations. Despite the recent separation of these populations, almost all individuals could be unambiguously assigned based on their composite genotypes, to one of two distinct populations, one comprising all of the European ruddy ducks we sampled (including those from Iceland and captive birds in the UK) and the other comprising all North American samples. Our results confirm that the European ruddy duck population is likely to derive solely from the captive population in the UK and we find no evidence of recent arrivals from North America or of admixture between ruddy ducks from Europe and North America.</p
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Harry S. Truman and the Potsdam Conference
No full textIn writing this thesis on the Potsdam Conference, I have attempted to explain the significance and events of the conference from the point of view of the United States delegation. In particular, I have tried to show Harry S Truman's actions and reactions when it came to a confrontation with the Allied Powers. From my research, I have developed a profound respect for the aptitude and leadership of this man. Therefore, I have devoted one chapter to a brief analysis of Truman's character, particularly as described by those around him. I have tried to show the characteristics which made Truman learn and develop leadership qualities especially needed in the world of diplomacy. | Since the Potsdam Conference was the last of the wartime conferences, it, more than any other conference, expressly reflects the end of cooperation between the United States, Great Britain, and the Soviet Union. And since it was Truman's first face-to-face confrontation with the Communist leadership, it could be cited as the starting point which was to lead to a much firmer United States stand toward the Soviet Union than practiced by President Franklin D. Roosevelt. In fact, in one sense, the lessons learned by Truman at this conference may have been the seeds that would later bloom into the Marshall Plan, NATO, and other post-war containment policies which are so closely associated with the Truman Administration.ProQuest Traditional Publishing Optio
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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