bluuebunny/crossref_metadata_2025_split huggingface dataset:
Orofacial morphology and feeding behaviour of the dugong, Amazonian, West African and Antillean manatees (Mammalia: Sirenia): functional morphology of the muscular‐vibrissal complex
Authors: Marshall Christopher D. , Maeda Hiroshi , Iwata Matsumitsu , Furuta Masami , Asano Shiro , Rosas Fernando , Reep Roger L. 
Published: March 2003

AbstractThe external orofacial morphology, perioral bristle distribution and feeding behaviour of Dugong dugon, Trichechus inunguis, T. senegalensis and T. manatus are described. Despite their differing orofacial morphology, dugongs and trichechids possess six similar regions: the oral disk, orofacial ridge, supradisk, chin and upper and lower bristle (modified vibrissae) pads. All living sirenians possess six discrete fields of bristles: four on the upper lip (U1, U2, U3, and U4) and two on the lower lip (L1 and L2). The distribution of these fields is similar among all living sirenians with the exception of the U1 bristle fields in dugongs. Perioral bristle field boundaries are distinguished by distinct changes in their length‐to‐diameter ratios. Both dugongs and trichechids possess bristle‐like hairs covering the oral disk, which possess length‐to‐diameter ratios intermediate between perioral bristles and postcranial hairs. Sirenians use elaborated facial musculature in conjunction with perioral bristles to acquire, manipulate and ingest aquatic vegetation. The U2 and L1 fields are the primary bristles used to ingest vegetation. The use of the L1 bristle fields is similar among all living sirenians. However, dugongs and trichechids are divergent in their use of the U1 and U2 bristle fields. Dugongs use the U2 bristles fields in a medial‐to‐lateral motion, while all trichechids use the U2 bristles in a prehensile, lateral‐to‐medial, grasping motion. These divergent behaviours presumably allow dugongs to exploit benthic foraging (i.e. consumption of rhizomes) to a greater degree than trichechids. Functional hypotheses of rhizome excavation are presented for both dugongs and trichechids.
Coexistence of jaguar (Panthera onca) and puma (Puma concolor) in a mosaic landscape in the Venezuelan llanos
Authors: Scognamillo Daniel , Maxit Inés Esperanza , Sunquist Mel , Polisar John 
Published: March 2003

AbstractJaguar Panthera onca and puma Puma concolor are sympatric throughout the jaguar's distribution. Although several studies have focused on the interactions between these two predators, the ecological and behavioural factors that promote their coexistence remain unclear. The goal of this study was to identify those factors that facilitate the coexistence of these cats in a mosaic landscape in the Venezuelan llanos. The study was conducted from January 1996 until November 1998. Five jaguars and six pumas were captured and radio‐collared. A high degree of spatial overlap was observed between jaguars and pumas, which may be related to the abundance and distribution of prey species. At a fine scale, there was little overlap of puma locations with jaguar locations. Both species were more active at night than during daytime, but seasonal differences were detected in the activity levels of these predators. Major segregation was found in food habits. Jaguars selected for large prey and pumas for medium‐sized prey. Jaguars selected for capybara Hydrochaeris hydrochaeris and collared peccary Tayassu tajacu and consumed caiman Caiman crocodilus and white‐tailed deer Odocoileus virginianus less than expected. Pumas selected just for collared peccary and also killed caiman less than expected. It is suggested that the abundance of medium‐sized prey is an ecological factor that is facilitating the coexistence of jaguar and puma in the study area. Habitat heterogeneity may be another influential factor leading to the coexistence. Seasonal differences in activity levels probably reflect differences in the size and species of prey taken by these cats.
Aquatic and terrestrial locomotor speeds of amphibious sea‐snakes (Serpentes, Laticaudidae)
Authors: Shine Richard , Cogger Harold G. , Reed Robert R. , Shetty Sohan , Bonnet Xavier 
Published: March 2003

AbstractAmphibious animals may be subject to strong but conflicting selective pressures to enhance locomotor performance both on land and in the water. Biomechanical models suggest that in snakes, adaptations to swimming (e.g. reduction of ventral plates, flattening of tail) will reduce their ability to move on land. The locomotor speeds of six taxa of amphibious (laticaudid) sea‐snakes, plus one entirely marine (hydrophiid) species were measured. Because the relative dependence on aquatic vs terrestrial habitats varies with a laticaudid's species, sex and body size, a previous study predicted that these factors should generate significant variation in locomotor speeds within laticaudids. Measurements of swimming and crawling speeds supported this prediction. Some species were faster than others and, within each species, males were faster than conspecific females. The degree of locomotor superiority of males was greater for terrestrial (>40%) than for aquatic (20%) locomotion. Smaller snakes were faster than larger animals in relative speed (body lengths/s) but slower in absolute terms (m/s). The hydrophiid Emydocephalus annulatus was slow in water as well as on land, perhaps because it eats immobile prey and thus, does not depend on speed for foraging. The diversity of locomotor abilities within laticaudid sea‐snakes provides a remarkable opportunity to identify factors that influence evolutionary trade‐offs between conflicting evolutionary optima.
Seasonal patterns in activity and habitat use by bats (Pipistrellus spp. and Nyctalus leisleri) in Northern Ireland, determined using a driven transect
Authors: Russ J. M. , Briffa M. , Montgomery W. I. 
Published: March 2003

AbstractThe seasonal activity of Leisler's bat Nyctalus leisleri and pipistrelle bats Pipistrellus spp. with respect to minimum bat numbers and habitat use were investigated in County Down, Northern Ireland using a driven transect from April 1998 to October 1998. Data were collected in lowland farmland near Belfast, Northern Ireland using two BatBox III bat detectors tuned to detect both species and species groups simultaneously. The number of bats/km increased during April, May and June, peaking in July and tailed off after this period. The main peak in July is assumed to reflect the occurrence of newly volant young. An increase in the number of pipistrelle social calls during August and September probably represented mating activity. Bat activity correlated with temperature in both N. leisleri and Pipistrellus spp., although bat numbers were independent of temperature after the middle of June. There was significant variation in habitat use by pipistrelle bats along roads over the study period. Pipistrelle bats were observed in greater numbers in areas of tree‐line, cut hedge (≤1 m high) and deciduous woodland, and increased further when these habitats bordered both sides of the road. Nyctalus leisleri was found in similar numbers in all habitat types and there was no seasonal variation in habitat use. The validity of this method for revealing seasonal variation in bat numbers and habitat use is discussed. Ambient climatic conditions may affect the number of bats recorded, while some species with long‐range echolocation calls, such as N. leisleri, may defy analysis of habitat associations.
Daurian pikas (Ochotona daurica) and grassland condition in eastern Mongolia
Authors: Komonen Minna , Komonen Atte , Otgonsuren Avirmed 
Published: March 2003

AbstractPikas (Ochotona spp.) are burrowing herbivorous mammals believed to play a keystone role in determining the biodiversity of steppe ecosystems. Impacts of domestic livestock grazing on the distribution and abundance of the Daurian pika Ochotona daurica were investigated in eastern Mongolia where the species is widespread and abundant. Effects of pikas on plant species richness and vegetation coverage were examined at different distances from burrow systems. Daurian pikas were nearly absent from severely grazed study sites, and incidence of the species increased with decreasing grazing intensity. The number of occupied burrow systems and usage of burrows was higher in sites with lower grazing pressure. Plant species richness and ground cover was higher at 3–12 m from the burrow systems than directly over burrows, suggesting that the effect of Daurian pikas is limited to the burrow system. Contradictory to previous studies on grassland pikas, this study indicates that Daurian pikas suffer from overgrazing and that their impact on grassland is only light.
Competition, predation risk and patterns of flock expansion in barnacle geese (Branta leucopsis)
Authors: Carbone C. , Thompson W. A. , Zadorina L. , Rowcliffe J. M. 
Published: March 2003

AbstractChanges in the spatial pattern of flocks of barnacle geese Branta leucopsis were examined in relation to individual behaviour during feeding visits to farm pastures. The flocks were photographed every 10–20 min, and the shape and location of the flock was determined from a plan view obtained from digitized images of the photographs. Flocks initially maintained a tight formation shortly after arrival, but then tended to expand with increasing residence time. The rate of expansion, however, was significantly greater in large flocks, with small flocks showing no consistent pattern. Observed rates of change in flock area were compared with those obtained from a simple model of flock movement in which individuals followed a random walk and moved at a constant speed. In contrast to the observed data, small simulated flocks (with relatively more edge birds) showed the greatest relative increase in flock area. This discrepancy between the data and the simulation can be explained mechanistically by differences in the behaviour of individuals in flocks of different sizes. In large flocks, birds at the leading edge of the flock had faster step rates and travelled further than birds in the centre and at the trailing edge. Rates of movement in small flocks did not vary with flock position. Levels of vigilance were higher during the first 10 min after arrival, in males, in smaller flocks and at the edges of flocks. Thus, upon arrival, flocks maintain a tight defensive formation with high vigilance, but with increasing residence time, vigilance decreases and larger flocks expand, suggesting a need for individuals to reduce feeding competition.
Effects of UV‐A and UV‐B on oxygen consumption in common toad (Bufo bufo) tadpoles
Authors: Formicki Grzegorz , Zamachowski Władysław , Stawarz Robert 
Published: March 2003

AbstractThe effects of UV‐A and UV‐B (Cracow District, Poland, 50°04′N, 19°57′E; 220 m a.s.l.) on oxygen consumption were studied in common toad Bufo bufo (L.) tadpoles (Gosner stage 27). Ecologically relevant chronic doses of UV were simulated in the laboratory. Larvae separated for experiment were derived from UV‐exposed or not exposed embryos. After hatching, tadpoles in stages 24–27 were treated with UV‐A or UV‐B. UV‐A caused significant increases in oxygen consumption in larvae grown from untreated embryos, whereas no changes occurred in tadpoles irradiated with UV‐A during embryonic and larval development. UV‐B caused significant decreases in oxygen consumption in all exposed tadpoles. The changes were larger in larvae derived from eggs not exposed to UV‐B than in tadpoles grown from UV‐B‐treated embryos. Our results suggest that ambient levels of UV‐A and especially UV‐B may affect the metabolic rate of common toad larvae living in shallow habitats. Affected respiration may retard development as well as increase the susceptibility of tadpoles to ecologically relevant pathogens. On the other hand, it seems that UV‐irradiation induces some adaptive processes during embryonic development, which increase the resistance of the larval respiratory system to solar UV radiation.
Observation of sea breeze interactions at and near Hong Kong International Airport
Authors: Lee O , Shun C M 
Published: March 2003

AbstractHong Kong International Airport (HKIA) is located in a coastal environment and is occasionally affected by sea breezes. High air temperatures relative to sea surface temperature, coupled with light winds or moderate east to northeasterly winds are favourable conditions for the development of a sea breeze at the airport. In the afternoon of 27 April 2000, sea breezes affected the airport and a sea breeze front was formed by convergence between the westerly sea breeze and strengthening easterlies. An aircraft landing at HKIA encountered the sea breeze front and reported wind shear with airspeed gain of up to 15 kt at a height of 30 m (100 feet) above ground. Surface wind observations and Doppler velocity data of a Terminal Doppler Weather Radar (TDWR) allow quantitative analysis of the wind shear event. Shortly after the wind shear event, the TDWR also captured interesting interactions between the sea breeze front and an area of passing showers. This paper presents a quantitative analysis of the wind shear event and observations of the sea breeze interactions by the TDWR. Copyright © 2003 Royal Meteorological Society
Numerical prediction of severe convection: comparison with operational forecasts
Authors: Speer Milton S. , Leslie Lance M. , Qi L. 
Published: March 2003

AbstractThe prediction of severe convection is a major forecasting problem in Australia during the summer months. In particular, severe convection in the Sydney basin frequently produces heavy rain or hail, flash flooding, and destructive winds. Convective activity is a forecasting challenge for the Sydney basin, mainly from October to April. Currently, there is a need for improved numerical model guidance to supplement the official probabilistic convective outlooks, issued by the operational forecasters. In this study we assess the performance of a very high resolution (2 km) numerical weather prediction (NWP) model in terms of how well it performed in providing guidance on heavy rainfall and hail, as well as other mesoscale features such as low level convergence lines. Two cases are described in which the operational forecasts were incorrect on both occasions. Non‐severe thunderstorms were predicted on 1 December 2000 but severe convection occurred. Severe convection was predicted on 8 December 2000, but no convection was reported. In contrast, the numerical model performed well, accurately predicting severe convection on 1 December and no convection on 8 December. These results have encouraged a program aimed at providing an enhanced numerical modelling capability to the operational forecasters for the Sydney basin. Copyright © 2003 Royal Meteorological Society
A study of thunderstorm‐induced delays at Frankfurt Airport, Germany
Authors: Sasse M , Hauf T 
Published: March 2003

AbstractIt is a well‐known fact that adverse weather significantly influences the safety and operating efficiency of air traffic, particularly in the terminal area. The unavoidable consequences of reduced operating efficiency are delays, diversions and cancellations of flights. In this paper the impact of thunderstorms on landing aircraft at Frankfurt Airport (Germany) during 1997 and 1998 is analysed. Thunderstorms are among the major weather phenomena affecting airport operations. Weather and operating conditions permitting, Frankfurt Airport is operated at more than 100% of its nominal capacity, which in turn lowers the actual capacity during periods of adverse weather. To the authors' knowledge this is the first quantitative study of weather impact on aviation in Germany. To identify thunderstorms as the unambiguous cause of delays, days without thunderstorms were used for reference and the difference in delay time was determined. The study shows that in 1997 thunderstorms increased the accumulated regular delay time by a factor of 6.3 and in 1998 by a factor of 1.1. On average, a thunderstorm typically caused about 740 delay minutes in addition to the 280 regular delay minutes for a sum of 100 arriving aircraft within four hours of average impact time. Copyright © 2003 Royal Meteorological Society
Using willingness‐to‐pay to assess the economic value of weather forecasts for multiple commercial sectors
Authors: Rollins Kimberly S. , Shaykewich Joseph 
Published: March 2003

AbstractThis paper uses an alternative to the usual cost‐avoidance approach to estimating the value of weather forecast products. Value is estimated via a demand‐based approach based on the willingness to pay of those who use weather forecast services. Contingent valuation is used to estimate the benefits generated by an automated telephone‐answering device that provides weather forecast information to commercial users in the Toronto area of Ontario, Canada. Commercial sectors included in the study are construction, landscaping/snow‐removal businesses, TV and film, recreation and sports, agriculture, hotel and catering, and institutions such as schools and hospitals. Average value per call varied by commercial sector, from $2.17 for agricultural users to $0.60 per call for institutional users, with an overall mean of $1.20 per call. At roughly 13,750,000 commercial calls annually, this would result in an estimate of benefits generated by the service to commercial users of $16,500,000 per year. Copyright © 2003 Royal Meteorological Society
The interpretation of non‐homogeneous hydrometeorological time series: a case study
Authors: Hall M J 
Published: March 2003

AbstractLong records of hydrological and hydrometeorological variables are of inestimable value for the planning, design and management of water resource systems. Unfortunately, such long series invariably exhibit inconsistencies and non‐homogeneities arising from a wide variety of causes –for example, changes in instruments and observation practices, and alterations to the general environment of the instruments themselves. Both non‐parametric and parametric statistical tests are available to detect the presence of long‐term movements in recorded time series, but the interpretation of results from such testing has often to be carried out in the absence of sufficient station metadata. A case study of precipitation records for 20 stations in Scotland over the period from 1961–99 has demonstrated that the results from statistical testing for inconsistency and non‐homogeneity should also be interpreted in the context of prevailing weather systems. In particular, the increases in both annual and winter (Dec–Feb) rainfall totals recorded during this period at sites in western Scotland appear to reflect the changes in the winter atmospheric circulation over the Northern Hemisphere as encapsulated in the North Atlantic Oscillation Index (NAOI). Sustained periods of positive values of the NAOI, albeit less severe than during those of the 1970s and 1980s, are evident in the historical record of this index. The trends in rainfall totals identified could therefore be interpreted as arising from natural variability or even greenhouse gas forcing rather than from any inconsistency and non‐homogeneity. Copyright © 2003 Royal Meteorological Society
Estimation of winter road maintenance costs using climate data
Authors: Venäläinen Ari , Kangas Markku 
Published: March 2003

AbstractIn Finland, winter road maintenance has been privatised, and the use of reliable predictors to measure the harshness of winter conditions has become even more important. Several indices have been developed to estimate the difficulty of winter conditions; however, many of these indices require relatively complicated input data and are in that sense vulnerable –for example, to changes in the meteorological station network. In the current study the year‐to‐year variation of the climatological variables describing maintenance costs were compared with the variation in costs. This made it possible to make a qualitative interpretation of the costs. This approach is ‘simple enough’ for its use to be easily accepted both by the contractors responsible for winter road maintenance and also by the administrators responsible for covering the maintenance costs. Copyright © 2003 Royal Meteorological Society
Development and testing of a high resolution mountain‐wave forecasting system
Authors: Vosper Simon 
Published: March 2003

AbstractA three‐dimensional numerical model for mountain waves is described and validated against radiosonde observations over the Isle of Arran, south‐west Scotland. The model is based on the Boussinesq equations of motion linearised about a background profile of wind, potential temperature and density. The equations are discretised using finite‐difference approximations and the time dependence is retained. Solutions are then computed by integrating forward the equations in time until a stationary mountain‐wave field is obtained. Data from radiosondes, launched during fieldwork on Arran during February and March 2000, are used to represent the background flow and model simulations of the wave field are compared directly with fluctuations in the ascent rates of the balloons. On average, the model reproduces the observed maximum peak‐to‐peak vertical velocity to within about 0.6 ms−1. In many cases the accuracy of the simulations is even better than this: the model vertical velocity along the path of the radiosondes agree well with fluctuations in the balloon ascent rate. The sensitivity of the model results to the wave ‘launching height’ is discussed. The model was also used to provide forecasts of wave activity during the field campaign. In this case, rather than using radiosonde data to represent the background flow, data were extracted from a global forecast model. The accuracy of these forecasts is examined and the viability of using such a model to provide routine operational high‐resolution mountain‐wave forecasts for specific sites is discussed. Copyright © 2003 Royal Meteorological Society
A diagnostic analysis of the Río de la Plata Superstorm, May 2000
Authors: Possia Norma , Bibiana Ceme S. , Campetella Claudia 
Published: March 2003

AbstractOn 16 May 2000, a low pressure system produced very intense winds over the Río de la Plata (RP) river, giving rise to floods within the region. In order to study this event, the synoptic evolution of the cyclone of 14–17 May 2000 is documented using conventional observations and the NCEP analysed data sets. The synoptic–dynamic overview reveals that the system starts as a usual cyclogenesis on the Chilean coast. The low level cyclone favours a convectively unstable environment within the central Argentinean region triggering convective storms and, consequently, a large amount of latent‐heat release. The latent heat and the vorticity advection both play an important role in determining the depth of the system and its movement. Another unusual feature of this event is the north‐eastward displacement of the cyclone, which is attributed to the interaction with other low‐pressure systems located in the South Atlantic Ocean. Copyright © 2003 Royal Meteorological Society
Animal colour vision — behavioural tests and physiological concepts
Authors: KELBER ALMUT , VOROBYEV MISHA , OSORIO DANIEL 
Published: March 2003

ABSTRACTOver a century ago workers such as J. Lubbock and K. von Frisch developed behavioural criteria for establishing that non‐human animals see colour. Many animals in most phyla have since then been shown to have colour vision. Colour is used for specific behaviours, such as phototaxis and object recognition, while other behaviours such as motion detection are colour blind. Having established the existence of colour vision, research focussed on the question of how many spectral types of photoreceptors are involved. Recently, data on photoreceptor spectral sensitivities have been combined with behavioural experiments and physiological models to study systematically the next logical question: ‘what neural interactions underlie colour vision ?‘This review gives an overview of the methods used to study animal colour vision, and discusses how quantitative modelling can suggest how photoreceptor signals are combined and compared to allow for the discrimination of biologically relevant stimuli.