bluuebunny/crossref_metadata_2025 huggingface dataset:
Is there any interspecific competition between dwarf crocodiles (Osteolaemus tetraspis) and Nile monitors (Varanus niloticus ornatus) in the swamps of central Africa? A study from south‐eastern Nigeria
Authors: Luiselli L. , Akani G. C. , Capizzi D.
Published: February 2006

Aspects of coexistence between the dwarf crocodile Osteolaemus tetraspis and the Nile monitor lizard Varanus niloticus were studied in swamp rain forests of south‐eastern Nigeria, central Africa. Crocodiles were significantly smaller than monitor lizards. There was no significant sexual size dimorphism in the examined sample of Varanus, whereas the female size exceeded the male size in Osteolaemus. The food niche breadth was narrower in young than in adults of both species, and V. niloticus showed a narrower niche breadth than O. tetraspis. Crabs constituted the main prey type category for both species, whereas vertebrates were more rarely preyed upon. The diet composition of males and females was similar in V. niloticus, but it was different in O. tetraspis. The general diet composition of the two species was similar (78.2% of overlap), and even the habitats where these two species were found were similar. These interspecific similarities suggest that O. tetraspis and V. niloticus could be potential competitors in the freshwater ecosystems of the Nigerian rainforest. However, it is suggested that the main prey type for these species (crabs) is not limited in the environment, which may minimize interspecific competition. Interference competition can also occur between these species, as suggested by one case of direct predation of the one species (V. niloticus) towards the other species (O. tetraspis). A case of cannibalism was observed in V. niloticus. This could indicate that intraspecific competition can be important for regulating the dynamics of monitor populations in the rainforests of south‐eastern Nigeria.
Decalcification of vulvar operculum and mating in the ocypodid crab Ilyoplax pusilla
Authors: Henmi Y. , Murai M.
Published: February 2006

In the mating system of Ilyoplax pusilla, wandering females respond to courting, burrow‐holding males that wave their chelipeds and enter their burrows. They pair in plugged burrows where mating occurs. Female I. pusilla spawned within 3 days of pairing, after which the male left. The opercula of females became decalcified, before, or more often after, pairing. Decalcification normally follows responsiveness to male courtship, but it is not necessary to produce female receptive behaviour, and pairing with a male in his burrow is not essential to evoke decalcification. After spawning, the numbers of calcified females gradually increased, and most ovigerous females were recalcified before larval release. The percentage of decalcified, single, non‐ovigerous females in the population peaked near the full and new moons. The peak percentage of decalcified, non‐ovigerous, paired females occurred 2 days later than that of decalcified, single, non‐ovigerous females. Decalcified females did not always enter male burrows for mating. Some females remained in their own burrows and laid eggs fertilized with stored sperm. Spawning with stored sperm may be an adaptation to avoid the risk of predation and it enables females, not evicted by neighbouring males, to reproduce.
Variation in spermathecal morphology and amount of sperm stored in populations of the simultaneously hermaphroditic land snail Arianta arbustorum
Authors: Baminger Helmut , Haase Martin
Published: February 2006

The morphology of the sperm storage organ (spermatheca) may influence the outcome of sperm competition in a variety of invertebrate species. Simultaneously hermaphroditic pulmonates show considerable inter‐ and intraspecific variation in the structure of the spermatheca. The morphological variation in the spermatheca (number of spermathecal tubules and tubule length) and the amount of sperm stored in the tubules in 115 individuals of the simultaneously hermaphroditic land snail Arianta arbustorum (L.) from six natural populations in the Eastern Alps (Gesäuse, Austria) was examined. The populations differed in snail density, therefore in the number of potential mating partners (range: 0.9–39.8 individuals/m2) and thus in the sperm competition risk. The number of spermathecal tubules ranged from two to nine. However, the six populations did not differ in either the mean number of spermathecal tubules, the length of the main tubule (range 0.9–3.4 mm), or in the cumulative length of the tubules (range 1.5–7.8 mm). The number of tubules and tubule length were not correlated with either shell height and shell breadth or with population density. The amount of sperm stored in the spermathecal tubules was estimated. Individuals from different populations did not differ in the amount of sperm stored, and the amount of sperm stored was not correlated with population density. Results indicate that the risk of sperm competition does not affect the complexity of the spermatheca (number of spermathecal tubules) in this snail. However, the possibility that individuals in high‐density populations store sperm from more different mating partners than those in low‐density populations remains to be examined.
The effect of parental age and experimentally manipulated brood size on the foraging effort and breeding performance of great skuas (Catharacta skua)
Authors: Ratcliffe N. , Furness R. W.
Published: February 2006

We examined the effect of a brood‐size manipulation on the foraging effort and chick rearing of known‐age great skuas Catharacta skua. Young birds were expected to refrain from increasing reproductive effort and opt for a strategy of brood reduction, while old birds were expected to increase effort and rear more young. Increasing brood size led to an increase in foraging effort and brood neglect. Enlarged broods had a lower mean survival rate, but similar growth rates to one‐ and two‐chick broods. Parents increased foraging effort to maintain chick growth rates at the expense of brood defence. This was associated with higher conspecific predation of enlarged broods. Foraging effort and chick feeding rate decreased with adult age. Younger adults increased foraging time in an attempt to satisfy the nutritional demands of the chicks, while older birds maintained a similar effort for all brood sizes. Younger adults achieved a lower fledging success despite their higher provisioning rates. Younger birds synchronized foraging and guarding duties less well, and so left the chicks unattended more often than older birds. As a consequence, their chicks suffered higher levels of conspecific predation. Defence of chicks through pair co‐ordination and aggression was thus an important component of successful breeding for great skuas.
Demography and population dynamics of the lacertid lizard Podarcis bocagei in north‐west Spain
Authors: Galán Pedro
Published: February 2006

The demography and life‐history traits of a population of the lacertid lizard Podarcis bocagei in north‐west Spain were investigated. Most of the conclusions presented are based on mark–recapture studies carried out over a 2‐year period. Reproductive characteristics are similar to those reported for other temperate‐climate lacertids. Clutch size, egg size and hatchling size (snout–vent length, SVL) are all positively correlated with the mother's SVL. Only large females lay more than one clutch per year. Growth rate is highest in young animals and declines gradually with age. In both sexes, sexual maturity is reached between the ages of 1 and 2 years. Again in both sexes, the probability of survival was fairly constant over the lifespan. Considering the study period as a whole, there was no significant between‐sex difference in survival probability. Among adults, the probability of survival was higher in winter than during other periods, but the differences were not statistically significant. The individuals of the study population are sedentary, making only short movements even when periods of up to 2 years are considered (the mean distance moved between marking and recapturing 18–24 months later was 15.7 m, maximum 45.6 m). On average, immature individuals move further than adults, and adult males move further than adult females. Estimated population density (all individuals) dropped from 1574 ha‐1 during the winter of 1989/90 to 1327 ha‐1 during the winter of 1990/91. The decline in population density over the study period was also reflected in the estimated net replacement rate for the population (0.85, i.e. considerably less than one), and is probably attributable to colonization of the study site by plants (reducing suitability as a habitat for P. bocagei). Estimated mean generation time was 2.09 years.
The proboscis of tapirs (Mammalia: Perissodactyla): a case study in novel narial anatomy
Authors: Witmer Lawrence M. , Sampson Scott D. , Solounias Nikos
Published: February 2006

The trunk‐like proboscis of tapirs provides a prime case study in the evolution of anatomical novelty. Morphological study of this unique structure was undertaken employing several specimens and a combination of analytical techniques: gross anatomical dissection, radiographic imaging and histological sectioning. Evolution of the proboscis of tapirs entailed wholesale transformation of the narial apparatus and facial architecture relative to perissodactyl outgroups. This transformation involved retraction and reduction of the bony and cartilaginous facial skeleton, such that several structures present in outgroups are completely absent in tapirs, including cartilages surrounding the nasal vestibule (e.g. alar and medial accessory cartilages, rostral portion of the nasal septum) and associated musculature (dilatator naris apicalis, lateralis nasi pars ventralis). At the same time, soft tissues surrounding the upper lip and nose became elaborated to form a mobile, fleshy proboscis. Several key facial muscles (e.g. levator labii superioris, levator nasolabialis, caninus, lateralis nasi) have been co‐opted to function in movement of the proboscis. The nasal vestibule is expanded and occupies approximately 75% of the nasal cavity. Vestibular expansion has compressed and simplified caudal components of the nasal cavity (e.g. reduction of dorsal and middle nasal conchae, loss of plica recta and plica basalis). The airway has become dorsally arched causing the ventral conchal complex to become inclined relative to the long axis of the skull. A few anatomical enigmas remain, such as the complicated maxilloturbinate that rostrally contacts the nasal septum and vomeronasal organ. Similarly, the meatal diverticulum, despite being both ancient and anatomically complex, has no obvious functional significance; it is clear that it is not homologous to the nasal diverticulum of horses and other equids. The reduction of the osseocartilaginous portion of the proboscis, coupled with expansion of the muscular and connective tissue components, has resulted in an organ that is best interpreted as a muscular hydrostat.
Group dynamics of humpback dolphins (Sousa chinensis) in the Algoa Bay region, South Africa
Authors: Karczmarski Leszek
Published: February 2006

Group dynamics of humpback dolphins Sousa chinensis inhabiting the Algoa Bay region on the south Eastern Cape coast of South Africa, were investigated by means of boat‐based photo‐identification surveys undertaken between May 1991 and May 1994. Groups of humpback dolphins varied in size from three to 24 animals (x̄= seven), with adults representing almost two‐thirds of the group members. Births occurred predominantly in summer. Some females, however, may also cycle outside of the apparent summer breeding season, perhaps indicating a secondary winter season. Circumstantial evidence suggests a minimum of a 3‐year calving interval. Maternal care lasts at least 3–4 years, but female–calf separation is seemingly not related to the female's next pregnancy. Humpback dolphins displayed varying degrees of residence/fidelity to Algoa Bay. Although a few individuals may possibly be classified as ‘resident’, most dolphins were infrequent visitors in the Bay and seem to be transient. The social system of humpback dolphins appears to be fluid with only casual and short‐lasting affiliations. Strong bonds between individuals other than mothers and calves are uncommon. Lack of consistency in the group membership appears to be the general pattern. The weak site fidelity and possibly extensive long‐range movement of the majority of dolphins may contribute to the dynamic nature of humpback dolphin groups. There is probably some form of segregation between sex and/or age classes among humpback dolphins in Eastern Cape waters. The nature and extent of this segregation, however, is not yet sufficiently understood. It is likely that the degree of site fidelity displayed by female humpback dolphins is related to their reproductive stage and increases during the nursing period. Mate‐searching behaviour of male humpback dolphins is the most likely reproductive strategy of the species.
Phylogenetic and taxonomical relationships of the eight species in the melanogaster subgroup of the genus Drosophila (Sophophora) based on the electrophoretic mobility of the major chorion proteins and the eggshell ultrastructure
Authors: Kalantzi‐Makri Maria C. , Trougakos Ioannis P. , Tafas Triantafyllos P. , Sourdis John , Margaritis Lukas H.
Published: February 2006

The eight species of the melanogaster species subgroup of the genus Drosophila were compared to each other with respect to: (a) the electrophoretic mobility of the major chorion proteins under SDS–PAGE; (b) the overall eggshell ultrastructure. The phylogenetic tree obtained using the first criterion showed that the eight species are divided into three clusters that contain the species of the melanogaster complex (D. melanogaster, D. sechellia, D. mauritiana and D. simulans), the two species of the yakuba complex (D. yakuba and D. teissieri) and the erecta complex species (D. erecta and D. orena). This clustering is in agreement to the generally accepted phylogeny of the subgroup based on exclusive criteria. The eggshell ultrastructure of the species at the main body of the egg revealed that the phylogenetically closely related species exhibit similar eggshell structure. We conclude that the criteria applied in this study could be eventually used in groups with unknown phylogeny to trace the phylogenetic relationships of the species.
Dry season camps of flying‐foxes (Pteropus spp.) in Kakadu World Heritage Area, north Australia
Authors: Tidemann Christopher R. , Vardon Michael J. , Loughland Ronald A. , Brocklehurst Peter J.
Published: February 2006

We investigated camps of black Pteropus alecto and red flying‐fox P. scapulatus in the early dry season of 1992 (April–June) in Kakadu National Park, a World Heritage Area in the wet‐dry tropics of north Australia. Fifteen camp‐sites were located and two types of camps were defined: main camps containing > 1000 animals and a significant component of young (P. alecto, n= 4; P. scapulatus, n= 2) and satellite camps of lesser size (P. alecto, n= 9; P. scapulatus, n= 3). The two species shared three camp‐sites. All camps were in dense riparian vegetation (fresh and saltwater mangroves, paperbark forests, closed forest and bamboo), overhanging or adjacent to water inhabited by crocodiles, that would provide a protected microclimate and protection from predators. All camps were within 5 km or less of one or more unoccupied sites that were indistinguishable in landform or vegetation from camp‐sites. In Kakadu NP riparian vegetation makes up about 6% of the park and is a non‐limiting resource for flying‐fox roosting. We propose that the initial colonization of camp‐sites is essentially random when roost vegetation is non‐limiting and that factors such as predation by humans, cyclones and fires determine the persistence and size of camps at the local level. At a broader temporal and spatial scale, interaction between the seasonal availability of forage and reproductive cycles is known to influence the location, size and structure of Pteropus camps. We advance the hypothesis that colonies of flying‐foxes could be moved to new camp‐sites, a strategy that would facilitate resolution of the frequently problematic management of these animals.
Courtship and mating in Empis (Xanthempis) trigramma Meig., E. tessellata F. and E. (Polyblepharis) opaca F. (Diptera: Empididae) and the possible implications of ‘cheating’ behaviour
Authors: Preston‐Mafham Kenneth G.
Published: February 2006

The courtship and mating behaviour of three empidid flies Empis trigramma, E. tessellata and E. opaca are described. In E. trigramma the male appears to use his complex genitalia to introduce a liquid ‘gift’ into the female's abdomen during copulation. This ‘gift’ is subsequently discharged and imbibed by the female. Such male ‘gifts’ may constitute a direct investment in their offspring, as females do not seem to acquire significant nutritional input from other sources. Males of E. opaca and E. tessellata present a ‘gift’ to the female, in the form of a dead insect, before mating takes place. Females will not mate with males which do not present a gift. Gifts presented during the period of sexual activity also appear to make a substantial contribution to female ovarian development. Some males seek to ‘cheat’ by presenting substitute gifts in the form of the fluff‐bearing seeds of willows. In E. opaca such ‘cheats’ enjoyed a low rate of reproductive success, compared with males presenting food gifts. ‘Cheating’ appears to be an alternative mating tactic for males of this species.
Parental and predatory behaviour of Scytodes sp., an araneophagic spitting spider (Araneae: Scytodidae) from the Philippines
Authors: Li Daiqin , Jackson Robert R. , Barrion Alberto T.
Published: February 2006

Parental care, especially as it relates to our understanding of sociality, is a topic that has received considerable recent attention in research on spiders (Aviles, 1997). Predatory strategies, including foraging decisions, prey preferences and predatory versatility, have also been emphasized in the recent literature. The present paper is concerned with both of these areas, parental care and predatory strategies. Scytodes sp. indet. is a versatile predator that captures prey either in its web or away from webs, and prey capture may be either by ambush or by active pursuit regardless of whether in the presence and absence of webs. The web is a sparsely woven sheet across a concave upper leaf surface, with a three‐dimensional tubular nest linked to the sheet via a small opening. Leaves may be green and living or brown and dead. In the field, a wide range of insects and spiders is taken, but jumping spiders (Salticidae) are the dominant prey. Predatory attacks are by spitting, with large prey being spat at repeatedly before being subdued. After spitting, the scytodid wraps prey in silk before feeding. Eggs are enclosed in a silk egg sac. The female uses her chelicerae to hold her eggs until hatching. After hatching, there is an extended mother–offspring association, with juveniles tending to remain in their mother's web until after the third moult. Females take prey to their juveniles and either feed alongside the juveniles or leave the juveniles to feed alone.
Demography, sociospatial behaviour and genetics of feral pigs (Sus scrofa) in a semi‐arid environment
Authors: Gabor Timothy M. , Hellgren Eric C. , Van Den Bussche Ronald A. , Silvy Nova J.
Published: February 2006

We examined demographics, dispersal, sex‐related behaviour, group structure, and genetic similarities of female feral pigs Sus scrofa on the Chaparral Wildlife Management Area in southern Texas from June 1993 to December 1995. Cumulative and seasonal ranges and core areas were calculated for 18 female pigs representing three distinct sounders. Simultaneous pairs of radio locations were used to assess behavioural associations among pigs, and DNA fingerprinting was used to determine genetic similarity. Behavioural and spatial associations largely corresponded to genetic relationships. Similarity of behavioural dendrograms to genetic dendrograms indicated that genetic relationships of feral pigs played a role in observed population structure. A single discrepancy between genetic and behavioural dendrograms suggested two animals dispersed to an adjacent sounder. Also, one sounder appeared to have been created by fission from a larger, adjacent sounder. Factors that are important keys in understanding the association between genetics and behaviour of feral pigs include dispersal, climate, habitat quality, population densities, and sex‐related behaviour.
Scaling of mammalian long bones: small and large mammals compared
Authors: Christiansen Per
Published: February 2006

Long bones from a taxonomically diverse assemblage of extant terrestrial mammals, spanning more than three orders of magnitude in body mass, have been measured in order to evaluate earlier models proposed for limb allometry as a means of physically coping with increased body size in large species. Linear regression models are unable to explain long bone scaling across a large size range of mammals, as differential scaling is present in large and small species and smaller species tend to approach geometric similarity to a considerably greater extent than larger species. Attempting to explain the morphology of the appendicular skeleton across the large size range of terrestrial Mammalia by means of a standard power function will probably inevitably lead to oversimplification, concealing underlying adaptations for coping with increased size. These include differences in limb posture, decrease in locomotory potential and greater duty factors during fast locomotion in large animals compared to anatomically similar smaller forms, and differential scaling of the appendicular skeleton in small and large mammals.
The distribution of play behaviour among Australian marsupials
Authors: Byers John A.
Published: February 2006

The distribution of play behaviour among the Australian marsupial families was surveyed. The rate of play in each species observed was categorized on a three‐point scale: 1 – no play observed or reported; 2 – play rudimentary; 3 – play common. Common play occurred in the larger‐bodied Dasyuridae, in Myrmecobiius, in Vombatidae, and in all Macropodoidea. In all other marsupials, play was rudimentary or absent. Categorical rate of play was not correlated with body mass or with metabolic rate but was correlated with relative brain mass. The distribution of play in Australian marsupials supported the hypothesis that play acts to modify brain development.
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

Distances 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

Foot 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

In 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

Diets 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

Macquarie 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

At 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

Four 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

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

We 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

Seasonal 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

A 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

New 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

The 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

The 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

Development 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

The 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.