bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanics of locomotion of dogs (Canis familiaris) and sheep (Ovis aries)
Authors: Jayes A. S. , Alexander R. McN. 
Published: August 2009

Records have been made of the forces exerted on the ground by dogs and a sheep, in walking, trotting, cantering and slow galloping. Film has been taken simultaneously. The difference between walking and trotting was much less marked for the sheep than for the dogs.Step length and stride length increase as speed increases. They are expressed as functions of the Froude number.The vertical component of the force exerted by a foot on the ground shows two main maxima in walking, except in the case of the fore feet of sheep. In this case and in other gaits there is only one main maximum. The vertical movements of the fore and hind quarters which occurred in examples of each gait have been calculated from the force records.The force exerted by a foot on the ground changes direction in the course of a step so as to remain more or less in line with a point fixed relative to the animal, but dorsal to its back.The force records show impact disturbances in the first 003 sec of contact of each foot with the ground.The point of application of the force on the sole of a foot tends to move posteriorly as the force increases.The results are discussed in relation to a theoretical account of the mechanics of locomotion on legs.
Histochemistry of the epidermis of the Chequered water snake Natrix piscator (Colubridae, Squamata)
Authors: Banerjee* Tarun Kumar , Mittal** Ajay Kumar 
Published: August 2009

Various histochemical techniques have been employed to distinguish the different cell layers within the epidermal generations of Natrix piscator.The oberhautchen and the thin superficial areas of the beta‐layer contain both alpha‐ and beta‐keratins and give moderate reactions with Papanicolaou's stain for keratin, for protein bound NH2 groups, basic proteins, and calcium; strong reaction for cysteine bound sulphydryl (SH) groups and very strong reaction for disulphide (SS) bonds of cystine. The remaining bulk of the beta‐layer gives weak reactions with Papanicolaou's stain for keratin, for NH2 groups, basic proteins, SH groups and SS bonds. The mesos and the alpha‐layers stain strongly with Papanicolaou's stain for keratin, for NH2 groups, basic proteins, sulphydryl groups and calcium, and weakly for mucopolysaccharides. The mesos layer also gives strong reactions for disulphide bonds and might contain both alpha‐ and beta‐keratins.The cells of the lacunar tissue are metabolically active as indicated by their normal nuclei and positive reaction for RNA. These cells contain granular glycogen, small amounts of acid mucopolysaccharides, NH2 and sulphydryl groups. The underlying layer of clear cells remain weakly or almost unstained with various histochemical techniques.The inner generation could roughly be divided into two layers–the presumptive beta‐layer and the presumptive alpha‐layer. High RNA contents in the presumptive beta cells indicate the active polymerization of keratin in this layer. These cells give weak reactions for protein bound NH, groups, basic proteins, SH groups and calcium. The remaining cells of the inner generation are not easily distinguished and contain small amounts of RNA.The differentiation of outer and inner generation in the hinge region is not clear. The thin outer oberhautchen and the beta‐layer give very weak reactions for NH, groups, SS bonds, SH groups and calcium and stain orange‐red with Papanicolaou's stain, bluish‐black with Verhoeff's elastin stain and pinkish red with Mallory's triple stain. The alpha‐layer resembles in its staining properties the alpha‐layer of the scale region.A large number of eosinophilic granular cells could be observed in the lower layers of the epidermis, especially in the hinge region and in the dermis.
The size, shape and orientation of pore grooves in the egg shells of Rhea sp.
Authors: Tyler C. , Fowler Sue 
Published: August 2009

In the egg shells of Rhea sp. there are grooves on the surface and it is into these grooves that one or more pore mouths open.Five egg shells of Rhea americana and four of Rhea darwinii were studied in detail in respect of the numbers of pore mouths and the number, length and orientation of the grooves. It was found that R. americana had nearly twice as many pore mouths and grooves as had R. darwinii. Their distribution in both species showed more and longer grooves and more pore mouths in the equatorial regions than in the polar regions of the shell. The grooves were also found to be approximately longitudinally orientated in the equatorial regions but this orientation became less marked towards the polar regions. Not surprisingly longer grooves tended to have more pore mouths than did shorter grooves, but, in addition, broader grooves were associated with greater length too.
Endocrine aspects of sexual mimicry in Spotted hyaenas Crocuta crocuta
Authors: Racey P. A. , Skinner J. D. 
Published: August 2009

Female Spotted hyaenas mimic the male in the possession of a peniform and highly erectile clitoris and false scrotum. Sex hormones have been assayed in the blood plasma, gonads and adrenal glands of male and female Spotted hyaenas and in the blood plasma of Striped and Brown hyaenas. Although the testicular concentration of testosterone greatly exceeds that of the ovaries in Spotted hyaenas, there is no significant difference between the sexes in the mean plasma levels of this hormone, or of the other androgen assayed, andro‐stenedione. In contrast, male Brown and Striped hyaenas have far higher plasma concentrations of testosterone than females.Testosterone levels in twin female Spotted hyaena foetuses were similar to the mean for adult females and it is suggested that high foetal androgen levels are responsible for the appearance of the male sexual facies in adult female Spotted hyaenas. The high plasma androgen levels recorded in adult females may also be associated with their aggression and dominance of males.
Characteristics and environmental determinants of natality, growth and maturity in a natural population of the desert scorpion, Paruroctonus mesaensis (Scorpionida: Vaejovidae)
Authors: Polis GaryA. , Farley RogerD. 
Published: August 2009

The scorpion, Paruroctonus mesaensis (Vaejovidae) has seven instar stages and moults six times. There is no post‐reproductive moult. The average growth ratio between successive instars is 1–38. The average rate of weight increase is 000249/day. This rate fluctuates seasonally: it is highest in spring and lowest in winter and summer. Growth rate is a function of ambient burrow temperature and prey abundance. Body size is determinate. The growth rate of the pectines is significantly greater in males as compared with females. Analysis indicates that the pectines are a secondary sexual trait in males.Animals mature from 19 to 24 months of age. Matings were observed from May through October. Gestation lasts 10–14 months. First surface appearance of newborn (instar II) is synchronous throughout the population and occurred in early August for five consecutive years. Some females were observed to be gravid for at least three consecutive years. Gravid females carry an average of 48–8 embryos. However, on the average only 19–9 young/female survive to appear on the surface. Factors which may be responsible for this observed decrease include resorption of embryos; death at birth, eclosion or first moult; and maternal and sibling cannibalism. The influence of various environmental factors on reproduction were analyzed. The number of newborn appearing on the surface and the population biomass of newborn showed a high positive correlation with precipitation and vegetation cover.
Feeding mechanics in primitive teleosts and in the halecomorph fish Amia calva
Authors: Lauder George V. 
Published: August 2009

The mechanics of feeding in Salmo gairdneri and Hoplias malabaricus, two generalized predaceous teleosts, was studied using high‐speed movies (200 frames per second). In Hoplias, the feeding mechanism is characterized by an extreme anterior swing of the maxilla and rapid depression of the hyoid occurring synchronously with mandibular depression and neurocranial elevation. A similar feeding sequence is observed in Salmo although the movements of the head are neither as extreme nor as rapid.The anterior swing of the maxilla, usually attributed to mandibular depression, increased when the ligamentous connection of the maxilla to the mandible was severed. A mechanical model of the jaw was constructed to elucidate the functional interrelationships of the neurocranium, maxilla and mandible.Films of the “holostean”Amia calva feeding show that the feeding mechanism is of a fundamentally different nature than that of primitive teleost fishes. Extreme anterior swinging of the maxilla occurs synchronously with jaw opening but branchiostegal expansion and hyoid depression only reach a maximum well after the jaws have begun to close. The existence of a highly efficient levator operculi—opercular series—mandible coupling is hypothesized on the basis of the rapid initial jaw opening.This pattern of feeding movements in Amia has necessitated a revision of current theories on the nature and significance of the “holostean”
The biology, functional morphology and taxonomic status of Gaimardia (Neogaimardia) finlayi (BivaMa: Gaimardiidae)
Authors: Morton Brian 
Published: August 2009

Gaimardia (Neogaimardia) finlayi Powell 1933 is a member of the little known family Gaimardiidae which collectively have an Australian, New Zealand and sub‐Antarctic distribution. N. finlayi nestles amongst algal holdfasts at the bottom of wave‐exposed beaches in New Zealand. It is a small, weakly heteromyarian dioecious bivalve attached by a relatively stout byssus. The mantle and the siphons are exceedingly simple; mantle fusions, other than anterior and posterior to the internal ligament, are of the inner folds only. The siphons are non‐extensible wide openings with few sensory papillae. Each ctenidium comprises an inner demibranch only with no inter‐lamellar and but a few inter‐filamentar junctions. Within the ctenidium large telolecithal eggs are incubated to a crawling, shelled stage of approximately 0–75 mm in length. Sperm were found in the ctenidium of two mature males. The possible storage of sperm and eggs and the incubation of fertilized eggs have survival value for a small bivalve living in a difficult environment.The modifications which suit N. finlayi to its mode of life are discussed, but major interest centres around the taxonomic position of the Gaimardiidae. It is concluded that the Cyamiidae and Gaimardiidae are very closely related, but more comprehensive studies on representatives of both families are needed.
Social ontogeny and behavioural diversity: consequences for Bighorn sheep Oris canadensis inhabiting desert and mountain environments
Authors: Berger Joel 
Published: August 2009

The development of social behaviour was studied in three natural populations of Bighorn sheep (Ovis canadensis). Individuals in all populations exhibited the same behavioural repertoires, but the utilization of specific behaviours among both infants and adults differed between populations. It was suggested that differences in the adult utilization of behaviour patterns result in part from behaviours used during infancy. In turn, the social and physical environments affected the development of subsequent behaviour patterns in sheep older than lambs.Desert sheep (in southern California) used mounting behaviours often, presumably because they matured sexually at an early age. Sheep in a more northern environment (British Columbia) used different behaviour patterns more frequently perhaps as a consequence of interactions experienced in larger bands. Additionally, playful interactions were reduced due to physical hazards in the desert, but they were at least nine times as frequent in the northern study population. Play in large groups resulted in the utilization of more different kinds of behaviour patterns. These behavioural findings are interpreted ecologically as consequences of inhabiting environments that differ socially and physically.
The functional anatomy of the shoulder in the Virginia opossum (Didelphis virginiana)
Authors: Jenkins Parish A. , Weijs W. A. 
Published: August 2009

The activity of 14 shoulder muscles and the excursions of the shoulder girdle and forelimbs were studied by simultaneous electromyography and cineradiography in nine opossums (Didelphis virginiana) walking on a treadmill at speeds of 0.52 m/sec to 0.95 m/sec. The relative magnitudes of vertical, propulsive, braking, and transverse forces engendered by the forelimb were measured by means of a force plate and correlated with skeletal postures determined by cineradiography. This study provides basic functional‐anatomical data on the shoulder of a generalized, noncursorial therian which bear on the interpretation of the structural evolution of the shoulder known from the fossil record of mammal‐like reptiles and early mammals.The infraspinatus, supraspinatus, subscapularis, atlantoscapularis, rhomboid, triceps and the cervical part of the serratus ventralis usually begin activity during the swing phase and continue throughout most, but not all, of the propulsive phase. The thoracic part of the serratus ventralis, the posterior belly of the omohyoid, the pectoralis, and the posterior part of the latissimus dorsi are active principally during the propulsive phase; EMG signals begin after foot contact and terminate before the foot is lifted from the substrate. The teres major and the anterior part of the latissimus dorsi are active principally during the transition from propulsion to swing phase. The deltoid, posterior trapezius, and atlanto‐acromialis are predominantly active during the swing phase, although variable and intermittent activity frequently occurs in the propulsive phase.Peak vertical forces engendered by the forelimbs are on the order of 57 % of body weight. During the propulsive phase the forelimb first exerts a braking and then a propulsive effect. Vectors representing vertical and longitudinal forces usually pass in front of the scapula during the initial part of the propulsive phase, through the scapula during mid‐propulsion, and behind the scapula by the end of propulsion. Transverse forces engendered by the forefeet are principally lateral.During mammalian evolution, scapular structure was altered by the addition of a supraspinous fossa, loss of the procoracoid, reduction of the coracoid, and reorientation of the glenoid fossa. The activity patterns of the supraspinatus, infraspinatus, and other muscles support the hypothesis that the mammalian shoulder evolved compensatory stabilizing mechanisms at the same time that it specialized for mobility.
The population dynamics of small rodents in a tropical African grassland
Authors: Cheeseman C. L. , Delany M. J. 
Published: August 2009

Monthly estimates were obtained of the density of small rodents in tropical grassland in Rwenzori Park, Uganda between April 1972 and September 1973. Of the 12 species of rodents present, the most numerous were Lemniscomys striatus, Lophuromys sikapusi, Mus triton, Mylomys dybowskii and Praomys natalensis. In a live trapping grid estimates were obtained using direct enumeration, numbers caught, Hayne's Lincoln Index and Jolly's method. Monthly estimates ranged between 16·67 and 63·32 animals per hectare. Intensive removal trappings were also undertaken and these gave estimates of 6·45 to 27·24 per hectare. The inconsistency of the two estimates may be accounted for by small microhabitat and vegetational differences.Breeding occurs in Lemniscomys and Praomys during the wet season whilen Lophuromys it is more extended but nevertheless seasonal. There is considerable evidence of rapid population turnover as the five species examined in detail had a mean duration of residence between two and three months. Few animals were resident for more than eight months.The monthly standing crop biomass ranged from 672 to 2221 g/ha on the live trapping grid and from 348 to 1126 g/ha on the intensive removal grids. Estimates of net annual production on the live trapping grid rely on a number of assumptions but are nevertheless relatively high ranging from 5897 to 7072 g/ha.Fires had a significant indirect effect on the composition of the fauna. Mus triton and Lemniscomys increased their numbers in the five months following the burn to levels not previously attained whereas Mylomys and Lophuromys were less frequent during this period. Several species of avian, reptilian and mammalian predators are recorded.
Reproductive behaviour of the Grey seal (Halichoerus grypus) on Sable Island, Nova Scotia
Authors: Boness D. J. , James H. 
Published: August 2009

We describe an unusual mating system, observed in a land‐breeding colony of Grey seal,Halichoerus grypus, in the western Atlantic. Males and females begin to visit the breeding beach about a week before the season begins, but none stay ashore for long until the first pup is born. The cows are gregarious, probably return to the same part of the beach to give birth from one year to the next, and tend to remain in the general vicinity of the birth site during their two and a half week sojourn ashore. Within these limits, however, they are quite mobile, and the size, location and composition of the temporary aggregations which they form vary from one day to the next. The cows become thinner and more sedentary as oestrus approaches, but otherwise they give no overt signs of receptivity. The males do not defend territories, nor do they form dominance hierarchies. Instead, they compete for tenure, the right to remain within the shifting population of females. Tenured bulls directly test the receptivity of nearby cows from time to time, and they continually manoeuvre in ways which maximize their chances of being next to cows which are either in oestrus or likely to become so in the near future. Bulls which fail to establish themselves amongst females try to intercept cows as they are leaving for the sea at the end of their season, but their reproductive success, estimated in several ways, is significantly lower than that of bulls with tenure.The system would be adaptive for seals which breed on the pack ice, but it is unique amongst land‐breeding pinnipeds. If, as some circumstantial evidence suggests, Grey seals were originally pack‐ice breeders, the persistence of such a system in a land‐breeding colony raises some interesting questions about the plasticity of mating behaviour.
Changes in egg shell characteristics of the Sparrowhawk (Accipiter nisus) and Peregrine (Falco peregrinus) associated with exposure to environmental pollutants during recent decades
Authors: Cooke A. S. 
Published: August 2009

In Britain since the late 1940s, the Sparrowhawk (Accipiter nisus) and Peregrine (Falco peregrinus) have laid eggs with unusually thin shells. DDT and its metabolites have been blamed. This paper reports how various properties of modern shells differ from those of older shells of normal thickness.For the shells of both species, there were roughly proportional reductions in thickness of the two main component layers, the mammillary and palisade layers, suggesting that thin shells resulted from a decreased rate of deposition. In addition, in modern Sparrowhawk shells, the resistant surface layer was especially deficient perhaps due to a further reduction in deposition rate or to slight premature termination. Shell thinning was associated with a proportionately greater decrease in shell strength. For the Peregrine, porosity, measured as the rate of passage of water vapour, was lower for the thin shells than for normal shells. This difference could not be explained by a change in the area of the pore channels, since the modern shells did not have fewer pores and the pore channels were the same size and shape in the two samples of shells. However, in the thin shells of both species, mammillae height increased relative to mammillary layer thickness, and in the Peregrine shells the extent of this increase was related to the change in porosity.
The role of fat and protein reserves in the annual cycle of the Grey‐backed camaroptera in Uganda (Aves: Syhidae)
Authors: Fogden M. P. L. , Fogden P. M. 
Published: August 2009

The annual cycle of Camaroptera brevicaudata was studied close to the equator in Uganda, particular attention being paid to the role of fat and protein reserves. Camaropteras breed at irregular intervals, two or even three times per year, whenever rainfall and increased primary productivity result in a favourable insect food supply. However, there is no consistent relationship between the onset of breeding and the onset of rainfall or any other environmental variable. It is concluded that an adequate protein reserve is the proximate factor controlling the onset of breeding.During the laying cycle the fat and protein reserves of female camaropteras fall significantly, though not synchronously. The decline of the fat reserve, which occurs on the days when eggs are being ovulated, appears to be related to loss of feeding time caused by searching for calcareous material needed for egg shell production. The decline of the protein reserve occurs almost throughout the laying cycle, but is small in relation to the total protein needed for the formation of a clutch of eggs. It is concluded that it represents a loss from a store of specialized protein needed for egg production, perhaps particular amino‐acids that are scarce in the normal diet. A similar small decline in the protein reserve of males may have a similar function in relation to sperm production. Courtship feeding of female camaropteras by the males is most intensive just before and during the laying cycle. It probably contributes to the nutrition of females by helping them attain adequate fat and protein reserves prior to breeding and by compensating for the time lost searching for calcareous material needed for egg shell production.The moult of camaropteras begins at about the same time each year, the timing probably being determined largely by the timing of the first, post‐juvenile, moult. The moult is extremely flexible—it can be interrupted if conditions become suitable for breeding, and its rate can be slowed if it coincides with severe dry conditions. This is an adaptation to an environment in which favourable conditions are irregular and too short to accommodate both breeding and moult.
Mortality in Grey seal pups: incidence and causes
Authors: Anderson Sheila S. , Baker John R. , Prime John H. , Baird Anna 
Published: August 2009

Pup production and mortality of beach breeding Grey seals was studied at two contrasting types of rookery, the cliff‐bound island of Ramsey, Dyfed, and the low, grassy island of Auskerry, Orkney. Thirty‐five per cent of pups died on Ramsey compared with 14 % on Auskerry. Almost half of the Ramsey mortality was accounted for by animals being lost from the beaches so that they were not available for analysis. The main proximate causes of death revealed by post‐mortem examination were starvation and infections. The other conditions which accounted for a small proportion of deaths were drowning, trauma, non‐viability, stillbirths, atelectasis, dystokia and heart abnormality. Certain pathogens associated with disease were common to both sites, while others were specific to Ramsey or Auskerry.The most important ultimate cause of pup deaths appeared to be failure of the mother/pup bond. The differences in levels of mortality between the sites is thought to be due to differences in the topography of the beaches. Pup survival on the narrow cliff‐bound beaches, or in caves, on Ramsey was reduced either directly through pups being washed off, or indirectly by overcrowding of animals at high tide.