bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distances at which jumping spiders (Araneae: Salticidae) distinguish between prey and conspecific rivals
Authors: Harland Duane P. , Jackson Robert R. , Macnab Aynsley M. 
Published: February 2006

AbstractDistances at which jumping spiders (Salticidae) use optical cues to distinguish between prey insects and conspecific rivals were investigated using adult males of 37 species. During tests, salticids walked up a ramp toward a mirror or toward an insect enclosed in a transparent petri dish. All species directed threat displays toward their own mirror images and the displays were comparable to each species' typical behaviour during male–male interactions. The salticids never displayed in tests with insects at the top of the ramp. The virtual distances at which the spiders displayed are interpreted as an indication of the distances at which each species can distinguish rivals from prey. Representative species were from the subfamilies Lyssomaninae, Spartaeinae and Salticinae. Discrimination distances relate well to the foveal layer I receptor mosaics of the anterior median eyes for the three subfamilies. Compared with the salticines, the lyssomanines and, except for Portia, the spartaeines tended to have shorter discrimination distances. Portia spp. had discrimination distances comparable to the longest recorded for the salticines. The longest discrimination distances found were for the salticine Mogrus neglectus (max. 320 mm or 42 body lengths) and for the spartaeine Portia fimbriata (280 mm or 47 body lengths).
Foot areas, ground reaction forces and pressures beneath the feet of kangaroos, wallabies and rat‐kangaroos (Marsupialia: Macropodoidea)
Authors: Bennett M. B. 
Published: February 2006

AbstractFoot areas of a wide range of kangaroos, wallabies and rat‐kangaroos were measured from fresh material and museum specimens. The areas of the plantar pads scaled according to the predictions of geometric similarity. The terminal claw areas of digits IV and V scaled with a lower than predicted exponent, reflecting functional demands of different species. The pressure that these marsupials exert on the ground during quiet standing is proportional to (body weight)0.35, and is considerably lower than those exerted by ungulates. Hopping kangaroos exert pressures proportional to (body weight)0.37. The pressures exerted by medium and large macropods are comparable to those of galloping ungulates. The findings support the commonly held belief that introduced grazing animals may cause greater mechanical disruption of the soil surface, leading to increased rates of soil erosion, than Australia's indigenous grazing fauna.
The relationships between echolocation calls, morphology and diet in insectivorous bats
Authors: Bogdanowicz W. , Fenton M. B. , Daleszczyk K. 
Published: February 2006

AbstractIn this study we explored quantitatively the relationships between the size of bats, the frequencies in their echolocation calls, and the incidence of moths and beetles in their diets. We focused on the predictions of the allotonic frequency hypothesis which states that some insectivorous bats increase their access to moths that can hear echolocation calls by shifting to frequencies to which the ears of these insects are less sensitive. The hypothesis predicts that the frequencies dominating the echolocation calls of bats may be correlated with the incidence of moths in their diets. We collected data for 62 species of bats that take airborne prey, usually flying insects, 25 species of high duty cycle echolocating bats (Rhinolophidae and Hipposideridae) and 37 species that are low duty cycle echolocators (Vespertilionidae and Molossidae). For bats whose echolocation calls are dominated by frequencies < 100 kHz our regression analyses showed a parabolic dependency between moth consumption (% volume or % frequency) and echolocation call frequency (kHz), supporting the allotonic frequency hypothesis. The use of echolocation calls dominated by frequencies outside the range of best hearing by moths may indeed increase the availability of these insects to the bats. However, when the same analysis was performed with only the bat species using echolocation calls dominated by sounds > 100 kHz, the relationship was not statistically significant, suggesting that morphological characteristics rather than echolocation call frequency may limit the range of potential prey items. Our analyses also demonstrate the importance of jaw morphology as a predictor of the incidence of beetles or moths in the diets of bats, and reveal that generally bigger species (as defined by forearm length) use echolocation calls dominated by lower frequencies than smaller species. In both high duty and low duty cycle echolocating bats the relationship between body size and dominant call frequency was best described by a linear model. We also propose that perch hunting was central in the development of the high duty cycle approach to echolocation.
Comparative feeding ecology of red (Cervus elaphus) and roe deer (Capreolus capreolus) in Scottish plantation forests
Authors: Latham J. , Staines B. W. , Gorman M. L. 
Published: February 2006

AbstractDiets of red Cervus elaphus and roe Capreolus capreolus deer in Scottish plantation forests were assessed by botanical and chemical analyses of 144 rumen samples. Samples were taken for summer and winter from four forests with a range of deer densities and ratios. Red deer ate mainly grasses in summer, and a mixture of sedges, rushes, grasses and heaths (ericoid plants) in winter. Roe deer ate predominantly forbs (herbaceous plants other than graminoids) in summer, and a mixture of forbs, heaths and tree and shrub browse in winter. The two species ate significantly different quantities of forbs and grasses (P < 0.001). Both species ate more grasses and forbs in summer, and more heaths in winter (P < 0.05). There were few differences between forests for either red or roe deer in diet composition or its seasonal variation. Washed rumen contents of roe deer contained more nitrogen than did those of red deer (P < 0.05) in both seasons, and both species contained more nitrogen in summer than in winter (P < 0.05). Proportions of the main plant categories within rumens were compared with their abundance recorded in the ground flora. These comparisons showed roe deer to be highly selective, whilst red deer ate plants in proportions similar to their availability. Niche overlap increased and dietary niche breadths widened during the winter. The main overlap was for heaths Calluna vulgaris and Vaccinium myrtillus in winter. However, C. vulgaris is widespread and common and competition was considered to be more likely for forbs and possibly V. myrtillus: the use of some forb species by red deer in summer may limit their availability to roe deer in winter, when they remain an important dietary item. Consideration of the different digestive specializations of the two species suggested that any dietary competition is likely to affect roe deer more than red deer.
Distribution and habitat use of the feral black rat (Rattus rattus) on subantarctic Macquarie Island
Authors: Pye T. , Swain R. , Seppelt R. D. 
Published: February 2006

AbstractMacquarie Island is the southernmost limit to the distribution of the black rat Rattus rattus. The species was introduced to this subantarctic island by sealers during the 19th century. The rats are now widespread and abundant in coastal areas all around the island. The distribution of rat populations is divided into discrete units by the availability of suitable habitat which, in turn, is a consequence of the rugged topography, particularly on the west coast. Rats are found from almost sea level to 200–250 m a.s.l. and up to 1 km inland. They have adapted successfully to the rigorous climate and firmly occupy a habitat niche in an environment where food is plentiful, predators are few and interspecific competition minimal. The principal habitat, tall Poa foliosa tussock grassland, provides year‐round shelter and food. Rats dig burrows in the peaty stools of the tussock plants and construct nesting chambers at the base of the dense leaf canopy. Predictably, this provides a warmer and more stable thermal environment than that experienced outside under the tussock canopy where the runs are located. Tussock grasslands are spreading under the influence of management control measures directed at the introduced European rabbit and possibly global warming. Management programmes are also directed towards the eradication of feral cats. In response, rat populations may be expected to expand in numbers and to occupy new territories. Without control this may, in the long term, have serious consequences for the island's avifauna, particularly the smaller, burrow‐nesting species.
Evening emergence of two nursery colonies of Leisler's bat (Nyctalus leisleri) in Ireland
Authors: Shiel C. B. , Fairley J. S. 
Published: February 2006

AbstractAt one nursery roost of Leisler's bat Nyctalus leisleri, the first bat often, and over half of the colony exceptionally, left before sunset. Departure was earlier during the period of lactation, when energy demands were highest. Consequently emergence data had to be standardized to allow for this before investigating possible associations with light intensity and meteorological factors. The importance of such standardization in general is emphasized. Emergence was earlier on overcast nights and was delayed with increased light intensity. The bats in a neighbouring roost, from which fewer data were obtained, also left earlier on overcast evenings, but departure was generally later than in the first roost, and there was no evidence of its being earlier during lactation. These differences between the roosts may be at least partially explained by the difference in size of the exit holes. At both roosts departure was mainly as a series of outbursts, and this was more marked during the first half of emergence. Rate of emergence increased with colony size. It was unusual for the first bat to leave more than 30 min, or for any bat to leave over 60 min, after sunset. Heavy rain inhibited or disrupted emergence.
Description of Hippopodina feegeensis and three other species of Hippopodina Levinsen, 1909 (Bryozoa: Cheilostomatida)
Authors: Tilbrook Kevin J. 
Published: February 2006

AbstractFour species of the genus Hippopodina Levinsen, 1909 are described from material originally attributed to Hippopodina feegeensis (Busk, 1884). The type species Lepralia feegeensis is redescribed and three further species of Hippopodina are recognized: H. pulcherrima (Canu & Bassler, 1928), H. iririkiensis sp. nov. and H. viriosa sp. nov.
Reproduction of two species of freshwater turtle, Chelodina rugosa and Elseya dentata, from the wet–dry tropics of northern Australia
Authors: Kennett R. 
Published: February 2006

Abstract Chelodina rugosa is a fast‐growing, carnivorous turtle that occupies seasonally ephemeral habitats, whereas Elseya dentata is relatively slow‐growing, largely herbivorous and confined to permanent water. Ovarian cycles followed an annual cycle of enlargement beginning in December (E. dentata) and January (C. rugosa), followed by ovulation and then follicular regression. Nesting season was determined from presence of gravid females, and for C. rugosa spans some 8 months from the late wet season until mid dry season, during which the turtle lays multiple clutches of eggs in underwater nests. Nesting may continue for longer when waterholes dry later following prolonged wet season rains. Nesting by E. dentata also begins in the late wet season but is complete by May and only one clutch is laid. Females of both species reproduce each year and clutch size and mass are related to female size. Annual spermatogenic cycles are similar in timing to those reported for temperate‐zone chelids but would be classified as pre‐nuptial because spermatogenesis begins before breeding. Gonial proliferation begins at the start of the wet season and spermiation coincides with the onset of ovulation. Mating was not observed but in C. rugosa probably occurs during December and January soon after turtles emerge from aestivation. Post‐mating storage of sperm in the epididymes did not occur in E. denatata but did appear to occur in some C. rugosa. The high reproductive output and extended nesting season of C. rugosa reflects its occupation of highly productive but unpredictable habitats and a reproductive strategy which ensures that some hatchlings meet optimal conditions for emergence. In contrast, the comparatively low fecundity and short nesting season of E. dentata, despite year‐round warm temperatures and access to permanent water, suggests that its reproductive output may be energetically limited by a largely herbivorous protein‐poor diet.
Genetically identical avian twins
Authors: Bassett S. M. , Potter M. A. , Fordham R. A. , Johnston E. V. 
Published: February 2006

AbstractWe report on the first established case of identical twinning in birds. The occurrence, genetic identity and subsequent development of identical emu (Dromaius novaehollandiae) twins is described, and comparisons drawn with single chicks hatched in the same season. The twin‐bearing egg, significantly larger than any other egg in the same clutch, was artificially incubated and hatching assistance was necessary. At hatching the female twins were small, but their combined weight approximated that of a single chick from an egg of equivalent weight, and by 18 months of age they were near average in size. DNA analysis of blood collected from the twins showed a complete match with 22 bands per sample larger than 3.8 kb. The estimated probability of this occurring by chance was 1.0×10‐13in two unrelated emu and 1.0×10‐6in siblings, indicating a high probability that the twins were identical.
Seasonal migration pattern and home range of roe deer (Capreolus capreolus) in an altitudinal gradient in southern Norway
Authors: Mysterud Atle 
Published: February 2006

AbstractSeasonal migration pattern and home range of radio‐collared roe deer (Capreolus capreolus) were studied in Lier, Norway, an area with a steep altitudinal gradient and a low population density of deer. Roe deer conformed to the usual pattern of temperate cervids with migration to low elevations during winter. Summer home‐range size increased with increasing altitude, and only a small proportion of individuals had home ranges at high altitudes. It is concluded that these high elevation areas were probably of low quality. Time of spring migration was later in deer with a high elevation summer range. A lower frequency of females (30.0%) than males (61.5%) was stationary, and more females (30.0%) than males (0%) were long distance migrators (> 10 km). This supports an earlier hypothesis that migration patterns of roe deer are also influenced by social factors.
Comparison of the diets of breeding royal (Eudyptes schlegeli) and rockhopper (Eudyptes chrysocome) penguins on Macquarie Island over three years
Authors: Hull C. L. 
Published: February 2006

AbstractA 3 year study of the diets of breeding royal Eudyptes schlegeli and rockhopper E. chrysocome penguins was carried out at two nearby colonies on Macquarie Island. Diets of both species were dominated by euphausiids and myctophid fish, in particular Euphausia vallentini and Krefftichthys anderssoni. Prey items were those found in the region of the Polar Frontal Zone, confirming the importance of this zone to these penguins. Diets of both species before hatching of the chicks were variable between years, and differences in quantity of food brought ashore and degree of digestion of prey suggested inter‐annual variation in distribution of prey resources. No dietary differences were detected in either penguin species across the breeding season, which reflected variability in diet at all stages, indicating that individual penguins foraged in separate areas. Significant differences between the two species were found, royal penguins consuming more myctophid fish and rockhopper penguins consuming more euphausiids. Differences were also found in the size class of prey items taken and the degree of digestion of food by both penguin species, indicating that prey were taken from different sectors of the ocean. It is concluded that the overlap in diet is small in individuals from these two spatially close colonies and, contrary to previous studies, indicates a separation in the resources used by both species. The contrast with previous studies is most likely a reflection of the different methods used to assess overlap and, to a lesser extent, the years and colonies in which the comparisons were made.
Stereoscan studies with descriptions of new characters of the egg and larval instars of Salticella fasciata (Meigen) (Diptera: Sciomyzidae)
Authors: Vala J.‐C. , Knutson L. V. , Gasc C. 
Published: February 2006

AbstractNew data on the morphology of Salticella fasciata immature stages are given from stereo scanning microscope observations. Distinctive features are presented for the egg chorion and the main sensorial structures of the cephalic, thoracic and abdominal segments of the larvae. In contrast to previous studies, the presence of float hairs on the posterior disc is clearly observed in the three larval instars. The ecological and phyletic significance of some characters are discussed.
The structure and blood‐storing function of the spleen of the hooded seal (Cystophora cristata)
Authors: Cabanac Arnaud J. , Messelt Edward B. , Folkow Lars P. , Blix Arnoldus Schytte 
Published: February 2006

AbstractThe mammalian spleen consists of white and red pulp and serves at least the dual purpose of immunological functions and filtration, and subsequent lysis of abnormal red blood cells (RBCs) from the blood. Seals are known to have very large spleens with a mass that, when fully dilated, amounts to about 2–4% of body mass. The red pulp in these animals serves as a temporary store for large amounts of (oxygenated) RBCs, which may be released during diving. In the present study the spleens of four hooded seals, which are known to be able to stay submerged for almost 1 h and reach depths in excess of 1000 m, were examined histologically. The hooded seal red pulp was found to contain perforated arterioles that communicate with interconnected fenestrated venous sinuses through which the blood commutes with an extravascular room. It is proposed that this extravascular room is engorged with blood in response to withdrawal of alpha‐adrenergic nervous tone to the splenic capsular smooth muscle, concomitant with dilatation of the splenic artery and increased splenic venous resistance. This will result in capsular dilatation and increased inflow of blood to the extravascular room, where RBCs may adhere reversibly to a mesh of reticular fibres, while the plasma fraction can escape back into circulation by way of the fenestrations. In preparation for the release of the RBCs, the opposite will happen – the capsula and the splenic artery constrict gradually, while the splenic veins dilate, and the RBCs are washed out. It is suggested that the release of the RBCs from the reticular fibres is facilitated by the release of a hitherto unknown substance, in response to beta‐adrenergic nervous stimulation.
Coalitions in male sugar gliders: are they natural?
Authors: Sadler Laila M. , Ward Simon J. 
Published: February 2006

AbstractThe sugar glider Petaurus breviceps is generally considered to be a polygynous, group‐nesting species. However, recent captive studies have indicated that dominance hierarchies and shared codominance amongst males formed when males were housed in multiple‐male, multiple‐female cages with male‐biased sex ratios. This study uses data from sugar glider groups in natural populations to assess the probability of male dominance hierarchies and the opportunity for codominant father–son coalitions. Nesting groups of sugar gliders were found to have female‐biased sex ratios ranging from 1:1.5 to 1:2.7 males:females. The dispersing sex was male – there were four records of recruitment into the natal group, all of which were female. Only one example was found of a long‐term adult male association between a father and putative son, which did not occur in the natal group of the son. The evidence suggests that though father–son associations may occur, the opportunities for male dominance hierarchies or male coalitions are rare in sugar glider nesting groups in the natural environment.
Ontogeny of the skull of the Australian lungfish Neoceratodus forsteri (Osteichthyes: Dipnoi)
Authors: Kemp A. 
Published: February 2006

AbstractDevelopment of the sensory lines, dermal skull bones, neurocranium, quadrate, mandible and hyoid apparatus of the Holocene Australian lungfish Neoceratodus forsteri is described, beginning at stage 40, before the formation of any skeletal elements, until skull development is complete in the sub‐adult fish. The sequence of the initial development of skeletal structures of the head and shoulder girdle reflects the need to feed and to acquire efficient gill respiration. The appearance of the neurocranium and dermal bones of the skull follows the formation of teeth, jaw bones and the cartilaginous quadrate, and the opercular bones, the skeletal elements directly associated with these functions. Dermal skull elements are closely related to the distribution of the sensory line system of the head. Each bone of the normal developing skull roof arises from a single centre of ossification, forming in a collagenous template secreted by mesenchymal cells. The numbers and arrangement of the skull bones found in the adult N. forsteri is the same as the pattern of bones laid down in the hatchling and juvenile, and the structures develop in an ordered and functional sequence.
Placental nutrition in a viviparous lizard (Pseudemoia pagenstecheri) with a complex placenta
Authors: Thompson Michael B. , Stewart James R. , Speake Brian K. , Russell Kylie J. , McCartney Ruth J. , Surai Peter F. 
Published: February 2006

AbstractThe composition of egg yolks and neonates of the viviparous lizard, Pseudemoia pagenstecheri, one of the most placentotrophic reptiles studied to date, are described. Neonates (43.3 ± 5.2 mg) have twice the dry mass of the initial eggs (22.0 ± 1.9 mg). The protein content of neonates (29.1 ± 1.1 mg) is more than twice that of eggs (12.2 ± 1.1 mg), while the energy content (908.1 ± 107.4 J) is 1.6 times higher than that of the egg (565.0 ± 42.9 J). The energy densities of eggs (27.5 kJ g−1) and neonates (23.1 ± 0.3 kJ g−1) are similar to the energy densities of eggs and neonates of oviparous species. The total ash per neonate (4.1 ± 0.4 mg) is three times greater than that of the egg contents (1.4 ± 0.2). Neonates contain significantly more calcium, sodium and potassium, but not magnesium, than do eggs. Thus, the placenta has a quantitatively important role in supplying nutrients for the embryo. The proportions of triacylglycerol (66%), phospholipid (19%), and free cholesterol (5%) in the eggs are similar to those in eggs of birds and crocodilians, but the proportion of cholesteryl esters (7%) is much higher in eggs of P. pagenstecheri. The proportion of docosahexaenoic acid in the egg phospholipid is relatively low (1.4%) but rises to 5.4% in the neonate. The eggs contain vitamin E (mainly in the form of α‐tocopherol) and vitamin A, but no detectable carotenoids. The overall composition of the eggs is not substantially different from that of oviparous species, suggesting that the small egg size relative to neonate size is a result of a reduction in egg size rather than modification by omission of some nutrients from the yolk. The pattern of placental nutrient provision of P. pagenstecheri contains both an obligate and a facultative component suggesting that enhancement of offspring quality through facultative placentotrophy is a general characteristic of placental reptiles independent of pattern of embryonic nutrient provision.