bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantification of badger (Meles meles) sett activity as a method of predicting badger numbers
Authors: Wilson G. J. , Delahay R. J. , de Leeuw A. N. S. , Spyvee P. D. , Handoll D.
Published: February 2003

Estimating the size of badger populations at a local scale using direct observation is difficult because of their nocturnal and elusive lifestyle. Methods based on live‐trapping can provide robust estimates of badger numbers, but are very labour‐intensive and expensive. The development of alternative methods to predict badger numbers accurately would provide valuable tools for research and management. Badger setts are distinct structures, which exhibit various signs of activity. The physical appearance of setts has been used in the past as a crude guide to the number of badgers likely to be trapped. In this study, an objective system for quantifying levels of activity at badger setts was developed and related to the number of trapped badgers. Several types of activity were positively associated with badger numbers, although these associations varied seasonally. Furthermore, all individual activity scores, summary indices and combinations of activity types were poor predictors of the number of badgers trapped. This is probably because variations in environmental conditions and badger behaviour confound the relationship between activity and badger numbers.
Home range and habitat use of the kit fox (Vulpes macrotis) in a prairie dog (Cynomys ludovicianus) complex
Authors: List Rurik , Macdonald David W.
Published: February 2003

The largest remaining black‐tailed prairie dog Cynomys ludovicianus towns in North America are in Mexico, where they coexist with the kit fox Vulpes macrotis, providing a unique opportunity to study the relationship between these threatened species. We hypothesized that the presence of prairie dogs would positively affect the kit fox population in our study area in north‐western Mexico, and that these influences would be manifest in home‐range size, density and habitat selection. We estimated fox densities fluctuating from 0.32/km2 to 0.8/km2, and radio‐telemetry revealed minimum convex polygon home ranges averaging 11 km2. These values are within the bounds of estimates from study sites elsewhere. Foxes used mesquite scrub less than expected, but grassland more than expected in relation to availability. Other habitats, including prairie dog towns, were used at random. Most (65.1% of 43) fox dens were in grassland, and were enlarged kangaroo rat Dipodomys spp. (34.9%) or prairie dog (34.9%) burrows. That kit foxes seemed to select grasslands rather than prairie dog towns was unexpected, particularly as prairie dogs are known to be a major component of kit fox diet. Foxes may reduce the amount of time they spend in prairie dog towns to avoid coyotes, which can be responsible for significant swift fox mortality. In our study area, coyotes were more active in prairie dog towns than in the grassland, where they were regularly shot. However, grassland used by kit foxes is a short‐lived product of prairie dog poisoning, which is quickly invaded by scrub, a habitat favoured by coyotes. We conclude that kit fox conservation initiatives in north‐western Mexico should be closely linked to conservation of the prairie dog ecosystem.
Warren building by European rabbits (Oryctolagus cuniculus) in relation to cover availability in a sandy area
Authors: Palomares F.
Published: February 2003

Warrens of the wild European rabbit Oryctolagus cuniculus are of concern in the Iberian Peninsula as a way to recover rabbit populations. However, there are no studies on the selection of sites where rabbits build their warrens. Between 1995 and 1997, in addition to warren size (number of entrances), the vegetation characteristics and the occurrence of tree roots in the ground surface occupied by warren entrances in Mediterranean scrubland and pastureland habitats were recorded in a sandy area of the Doñana National Park. Pastureland warrens were about twice as large as warrens in Mediterranean scrubland, and 1.8–1.4 times larger in the first study year than in the other 2 years. Warrens in pastureland were built more between tree roots (13.3–17.8%) than those built in Mediterranean scrubland (0.7–1.8%). In Mediterranean scrubland, most of the ground surface occupied by warren entrances was under tall shrubs (79.7–87.9%), with some under short shrubs (4.5–7.4%). In pastureland, these figures were 2.0–3.8% for tall shrubs, and 17.2–19.8% for short shrubs. Warrens were built between tree roots significantly less than expected in the Mediterranean scrubland, and slightly more than expected in the pastureland. Whereas warren surface was occupied by short shrubs significantly less than expected in the Mediterranean scrubland, the opposite pattern occurred in the pastureland; however, in both habitats tall shrubs were significantly preferred. These results suggest that rabbits may seek protection against collapsing warrens by selecting sites with some supporting structures such as the roots of trees or shrubs. Scrubland vegetation (preferably tall shrubs) should be favoured for medium‐ and long‐term habitat management of areas aimed at supporting large rabbit populations. Furthermore, in sandy areas, some kind of stable ground support and external protection should be provided when creating artificial warrens for rabbits.
Taxonomic status and conservation relevance of the raccoons (Procyon spp.) of the West Indies
Authors: Helgen Kristofer M. , Wilson Don E.
Published: February 2003

Raccoons Procyon spp. from New Providence Island in the Bahamas and from Barbados and Guadeloupe in the Lesser Antilles have traditionally been recognized as distinctive species endemic to their respective islands. All three of these ‘species’ currently possess official conservation status of high concern. Bahamian and Guadeloupean raccoons are recognized as endangered species by the World Conservation Union (IUCN), which also considers the Barbados raccoon to be a recently extinct West Indian mammal. However, historical, biogeographic, genetic, and morphological evidence demonstrate that all three West Indian raccoon populations are the result of human‐sponsored introductions from the eastern U.S.A. that have occurred in the past few centuries. Accordingly, these animals should not be considered either conservation priorities or recent losses of biodiversity in the Caribbean. Instead, they may actually represent ecological threats to the insular ecosystems on their respective islands. Procyonid conservation goals must be re‐examined and updated accordingly.
Effects of ultraviolet‐B radiation on metamorphic traits in the common frog Rana temporaria
Authors: Pahkala M. , Merilä J. , Ots I. , Laurila A.
Published: February 2003

Effects of ultraviolet‐B (UV‐B) radiation on amphibian embryonic and larval development have been investigated in a number of studies, but the effects on later life‐stages (metamorphosis) have received less attention. Hence, the effects of UV‐B radiation treatments (control (no UV‐B), normal and 26% enhanced levels of UV‐B) on the development of the common frog Rana temporaria embryos from fertilization until metamorphosis were investigated. Survival until metamorphosis was significantly higher among individuals exposed to normal, as compared to individuals sheltered from, UV‐B or those exposed to enhanced levels of UV‐B radiation. There were no effects of normal or enhanced levels of UV‐B radiation on the frequency of developmental anomalies. However, UV‐B radiation delayed the timing of metamorphosis in a dose‐dependent fashion, and the individuals from the normal and enhanced UV‐B treatments metamorphosed at smaller size than those raised in the absence of UV‐B radiation. These results suggest that UV‐B radiation experienced through embryonic and larval stages can have negative effects on the growth and development of R. temporaria. Delayed metamorphosis at reduced size is also likely to lower the fitness during later life‐stages.
Non‐random nestling mortality in northern fulmars: implications for monitoring marine environments
Authors: Gray Catherine M. , Phillips Richard A. , Hamer Keith C.
Published: February 2003

Chick growth and food provisioning of northern fulmars Fulmarus glacialis were studied at Fair Isle, Shetland, in 2 years of contrasting environmental conditions. Low sandeel Ammodytes marinus availability resulted in very low breeding success in many seabirds in Shetland in 1998, whereas breeding success in 1997 indicated a normal season. Fulmars at Fair Isle experienced lower chick survival in 1998 than in 1997. There were also significant differences in diet and food provisioning in the 2 years; sandeels were the most abundant prey items in 1997, but were completely absent from the diet in 1998. High nestling mortality occurred shortly after hatching in 1998. Those chicks that survived this episode had previously been heavier for their age, and remained heavy throughout development in comparison to chicks in 1997, despite a continued absence of sandeels from the diet. Surviving chicks in 1998 were subsequently fed comparatively small meals at frequent intervals, but with no overall difference in the amount of food delivered. We discuss the implications of differential mortality and resulting growth patterns for the use of seabird breeding parameters to monitor marine environments.
Patterns of helping effort in co‐operatively breeding banded mongooses (Mungos mungo)
Authors: Cant Michael A.
Published: February 2003

In most co‐operative breeding species, some individuals contribute much more to helping behaviour than others. The most well‐established explanation of such variation is based on kin selection and suggests that, in the absence of detectable differences in relatedness, individuals who suffer lower costs for a given level of help should contribute more. Differences in helping effort between dominance/sex categories were investigated in co‐operatively breeding banded mongooses Mungos mungo in Uganda. The most conspicuous form of help in this species is provided by individuals who babysit offspring at the den while the rest of the pack goes off to forage. Across eight groups, the survival rate of pups increased with the average number of babysitters guarding them, consistent with the hypothesis that helpers benefit the brood that they guard. There was no difference between dominant males, subordinate males and breeding females in total contributions to babysitting. Subordinate males, however, contributed more to babysitting in the mornings, which were the longest and presumably the most energetically expensive sessions of the day. In six litters in one well‐studied pack, dominant males and breeding females reduced their contribution to babysitting for the period that females were in oestrus. By contrast, subordinate males increased their contribution to become the main babysitters during this time. These results are consistent with the hypothesis that, where helping conflicts with breeding, individuals with little chance of direct reproduction can help at a lower fitness cost than those with a high probability of successful reproduction.
Algophagus mites (Astigmata: Algophagidae) from the sub‐Antarctic Prince Edward Islands: habitat‐related morphology and taxonomic descriptions
Authors: Marshall David J. , OConnor Barry M. , Pugh Philip J. A.
Published: February 2003

Five populations of habitat‐specific, morphologically distinct Algophagus mites (Astigmata: Algophagidae) were found to occur on the sub‐Antarctic Prince Edward islands. Although these mites did not differ among themselves with respect to idiosomal setal characteristics, which were also similar to those of known sub‐Antarctic Algophagus taxa, morphometric analyses revealed leg and idiosomal size differences. In addition to morphometric differences, leg setal positions and porose axillary organ structure, indicated that the morphotypes were taxonomically discrete. The taxa were found to include the known A. antarcticus Hughes, 1955, A. laticollaris Fain, 1974 (new status), a sub‐species of A. semicollaris Fain, 1974, and two new species, A. brachytarsus sp. nov. and A. macrolithus sp. nov. With the exception of A. semicollaris, the taxa are described or redescribed in this paper. Morphological features of the females in particular, and notably leg proportions, claw dimensions, and apodeme positions, corroborate discrete terrestrial (A. brachytarsus and A. macrolithus) and aquatic forms (A. antarcticus, A. laticollaris, and A. semicollaris), and vary in a manner suggesting a functional relationship to habitat occupation by the various taxa.
Grey seal (Halichoerus grypus) pup mortality not explained by local breeding density on North Rona, Scotland
Authors: Twiss S. D. , Duck C. , Pomeroy P. P.
Published: February 2003

Pre‐weaning pup mortality of grey seals Halichoerus grypus in a breeding colony (North Rona, Scotland, U.K.) was examined in relation to the density of local adult females over two breeding seasons. Accurate, fine‐scale maps of daily seal locations within a GIS database permitted the extraction of measures of female density determined at a range of spatial scales from 5 to 50 m around each pup on the date of death. Adult densities around live pups provided the null distribution of adult densities, which were tested against the distribution of densities where deaths occurred. Pre‐weaning pup mortality at this colony was not related to any of our density measures. The proportion of pups dying each day showed no seasonal trends. Analysis of topographic features from a sub‐meter digital terrain model for locations where deaths occurred suggested that there were fewer mortalities in prime pupping habitats. This could have been a direct effect of habitat or the relative quality of mothers in these habitats. The distance separating mothers and pups tended to be greater on the periphery of the colony compared to more central areas. Pups in the peripheral areas may be more exposed to predation by gulls.
When does a reproducing female viper (Vipera aspis) ‘decide’ on her litter size?
Authors: Lourdais Olivier , Bonnet Xavier , Shine Richard , Taylor Emily N.
Published: February 2003

Some organisms rely on stored energy to fuel reproductive expenditure (capital breeders) whereas others use energy gained during the reproductive bout itself (income breeders). Most species occupy intermediate positions on this continuum, but few experimental data are available on the timescale over which food intake can affect fecundity. Mark–recapture studies of free‐ranging female aspic vipers Vipera aspis have suggested that reproductive output relies not only on the energy in fat bodies accumulated in previous years, but also on food intake immediately before ovulation. A simple experiment was conducted to test this hypothesis, maintaining female snakes in captivity throughout the vitellogenic period and controlling their food intake. The energy input of a female strongly influenced the amount of mass that she gained and the number of ova that she ovulated. Multiple regression showed that litter size in these snakes was affected both by maternal body condition in early spring (an indicator of foraging success over previous years) and by food intake in the spring before ovulation. Our experimental data thus reinforce the results of descriptive studies on free‐ranging snakes, and emphasize the flexibility of energy allocation patterns among vipers. Reproducing female vipers may combine energy from ‘capital’ and ‘income’ to maximize their litter sizes in the face of fluctuating levels of prey abundance.
A remarkable young Scolecomorphus vittatus (Amphibia: Gymnophiona: Scolecomorphidae) from the North Pare Mountains, Tanzania
Authors: Loader Simon P. , Wilkinson Mark , Gower David J. , Msuya Charles A.
Published: February 2003

A description is given of the external morphology of a single young caecilian (gymnophionan) amphibian from the North Pare Mountains, Tanzania, referable to Scolecomorphus vittatus (Boulenger, 1895). This is the smallest known free‐living Scolecomorphus, and it is characterized by many remarkable features previously unrecorded for any life‐history stage of any caecilian. The cheeks have conspicuous, posteroventrally divergent paraoral processes that border a concavity on the ventral surface of the snout. The mandibles are very flexible about their articulation with the cranium, and they have a broader curvature than the upper jaw. The dentition is heterogeneous, with adult‐like monocusped teeth in single rows, but also some supernumerary teeth, some of which are bicornute. The posterior parts of the paraoral processes bear a small number of monocuspid teeth that lie outside, and project away from, the mouth. The nuchal region of the body bears a distinctive concavity on the underside of the throat, bordered by longitudinal ridges that terminate in fleshy nipples. All of these features are unknown in adult Scolecomorphus, and many are unique for caecilians, and they suggest a highly distinctive life‐history stage. The discovery and description of this specimen adds substantially to the currently meagre information on the life history of scolecomorphids and of the diversity of caecilian reproductive biology. Two modes of viviparity in caecilians are identified, with S. vittatus resembling the caeciliid Geotrypetes in giving birth to small altricial young that seem to require extended post‐parturition parental care.
Size and growth of the crabeater seal Lobodon carcinophagus (Mammalia: Carnivora)
Authors: Laws R. M. , Baird A. , Bryden M. M.
Published: February 2003

Growth in length and weight of a large sample of crabeater seals Lobodon carcinophagus collected over the period 1967–78 is reported. Growth in dorsal standard length of 1146 seals (490 males, 656 females) from 0.5 to 20 years of age was similar to the pattern seen in other phocid seals. Length was plotted against age and Gompertz curves fitted to the data. Growth rates were estimated from the derived equations: males, y= 231.9 − 58.7 e−0.55t; females, y= 236.8 − 63.6 e−0.44t. The asymptote is at approximate length 234 cm and age 10 years in both males and females. Body weights were recorded for 249 seals aged from 0.5 to 20 years, of which reliable age estimates for 230 (100 males, 130 females) were available. Rates of growth in body weight were estimated from the derived equations: males, y= 200.0 − 94.1 e−0.48t; females y= 212.4 − 116.2 e−0.40t. The best estimate of body weight from linear body measurements is obtainable from a predictive equation relating body weight, length and axillary girth, determined by maximum likelihood: W = 0.000046 LG2 (W, body weight; L, dorsal standard length; G, axillary girth). There was no significant difference between the sexes. Seasonal variations in body condition could not be determined because all animals were sampled in February and March. However, inter‐year differences in recovery of body condition of adults, following the demands of breeding and moulting in the spring and summer, were observed. The data represent a unique time series covering the 1960s and 1970s. In terms of global climate change they should provide a valuable baseline for future studies.
Miombo woodland termite mounds: resource islands for small vertebrates?
Authors: Fleming Patricia A. , Loveridge John P.
Published: February 2003

Macrotermes mounds are a significant feature of African woodland landscape, contributing to habitat heterogeneity. The mounds are massive, often many centuries old, and support dense vegetation and a suite of woody plant species scarce in surrounding woodland. The present study tested the hypothesis that Zimbabwean Macrotermes mounds, with their greater niche availability, were more heavily utilized by small vertebrates than the surrounding miombo woodland. We carried out a survey of amphibian, reptile and mammal species during early and late rains for 16 termite mounds and 16 adjacent woodland habitat sites, and compared numbers of individuals, species and diversity. For amphibians and reptiles, individual numbers and species did not differ significantly between habitats and their activity was more influenced by season. For mammals, however, significantly more individuals and species were captured on termite mounds, with three species captured only on mounds (most notably the musk shrew Crocidura hirta spp. complex) and all others showing marked preference for this habitat. The greater number of mammals on termite mounds contributed to total small vertebrate biomass being 800 g/ha for termite mounds compared with 380 g/ha in woodland. For mammals certainly, Macrotermes mounds provide significant food and habitat in miombo woodland.
Scaling migration speed in animals that run, swim and fly
Authors: Hedenström Anders
Published: February 2003

Overall migration speed is likely to be a trait under selection pressure in animals migrating annually between habitats for reproduction and survival. A general expression was used for migration speed (Vmigr), accounting for energy accumulation and transport, and derive how Vmigr scales with body mass for three types of migratory locomotion: running, swimming and flying (powered and soaring flight). Migration speed is predicted to increase with increasing body mass in animals that run (∝m1/11), swim (∝m1/24) and fly by soaring (∝m0.22), whereas in animals migrating by powered flight it decreases (∝m−1/4). How the relative duration of fuel accumulation to that of migratory locomotion scales with body mass is also derived. This proportion should increase in animals that run and fly, but should remain unaffected by body size in swimmers. The suggestion is made that in runners and swimmers, selection for enhanced migration speed could provide an explanation to Cope's rule, i.e. the observation that body size gradually tends to increase over time.
Pseudonovibos spiralis: epitaph
Authors: Galbreath G. J. , Melville R. A.
Published: February 2003

Timm et al. (2001) argue that Pseudonovibos spiralis actually exists as a new bovine species, and identify as such two frontlets in the Kansas Natural History Museum, U.S.A. This is not the first time these specimens have been the subject of dubious taxonomic identification; they were previously misidentified by Hoffman (1986) as female kouprey Bos sauveli. A further irony is that the original unmasking (Dioli, 1995) was accomplished by an author of the current defense.
Niche separation in sympatric jackals (Canis mesomelas and Canis adustus)
Authors: Loveridge A. J. , Macdonald D. W.
Published: February 2003

Niche separation (along habitat use, activity and dietary axes) between two sympatric jackal species, Canis adustus and Canis mesomelas, was investigated in north‐west Zimbabwe. Diet of the two jackal species was flexible and opportunistic and dietary overlap between the jackal species was high. However, C. mesomelas ate more springhares Pedetes capensis, and C. adustus ate more safari camp refuse. To a large extent, differences in diet reflect availability within home ranges. Although interspecific home ranges overlapped by up to an average of 26%, the two species did not intensively use the same areas, and favoured different habitats. Canis mesomelas defended territories in the grassland habitat, which was also the favoured habitat of springhares, the predominant vertebrate prey species in the area. Canis adustus centred their home ranges on centres of human activity, benefiting from the regular, but low quality, anthropogenic food resources. In this study, C. adustus, with the more generalist dentition, had a broader niche than C. mesomelas (dietary diversity C. adustus=4.14; C. mesomelas=3.45). Within sympatric areas, differing activity times may further operate to decrease competition, allowing these canids to co‐exist. The activity times of the two species differed, with C. adustus being almost entirely nocturnal. Canis mesomelas, while mostly nocturnal, was also active during the morning and in the late afternoon. The jackals in this study did not have clear‐cut niches and it is probable that the extreme flexibility of canids in both diet and behaviour allows these species to co‐exist sympatrically over part of their range.
Reduced dispersal and opportunistic territory acquisition in male lions (Panthera leo)
Authors: Funston Paul J. , Mills Micheal G. L. , Richardson Philip R. K. , van Jaarsveld Albert S.
Published: February 2003

Life‐history patterns in lions Panthera leo living in savanna woodlands of the Kruger National Park, South Africa, were investigated and compared with those of the Tanzanian ‘plains‐like’ ecosystems (e.g. Serengeti Plains and Ngorongoro Crater). First, lower levels of mortality in the juvenile age classes were found in Kruger lions, which in turn, extend the inter‐birth period. A further difference was a prolonged period of association of sub‐adult males with their natal pride, either directly or in a land tenure system that has not been described previously. Most (80%) of young male coalitions rather than becoming nomadic, remained close to their natal territory after leaving the pride, either as non‐territorial sub‐adults or adults and even as territorial adults. Only 20% of coalitions did not stay close to their natal range, one of which acquired a territory 20 km away from its natal pride. The pattern of territory acquisition, in fact, was one in which the majority of holders acquired territories close to their natal ranges. These behaviour patterns contrast markedly with those from ‘plains‐like’ ecosystems where dispersing males usually move far away from their natal pride's range (>200) km and often remain nomadic for extended periods of time. Dense bush and access to sufficient prey resources in the form of resident buffalo Syncerus caffer herds may be important factors allowing extended residence near the natal pride's territory. Buffalo were more available in our study area habitat than in neighbouring habitats, and comprised the majority of male lion kills. Extended male residence contrasts markedly with current theory on dispersal in polygynous mammals, which holds that only one sex (females for lions) gain an advantage by staying close to the territory of their natal pride. In Kruger it seems that both sexes gain an advantage by not dispersing far, and use currently undocumented mechanisms to avoid inbreeding.
Breeding biology of the reverse‐dichromatic, co‐operative parrot Eclectus roratus
Authors: Heinsohn Robert , Legge Sarah
Published: February 2003

The breeding biology and social system of the eclectus parrot Eclectus roratus, a species with a unique form of sexual dichromatism (red and blue females, green males) was examined. Our 4‐year study at Iron Range National Park on Cape York Peninsula, Australia, showed that females guarded their nest hollows in emergent rainforest trees for up to 9 months each year, often starting well before they laid their first clutches early in the dry season. During this time they rarely left the nest and relied on males for food, both for themselves and their nestlings. Intrasexual competition for scarce hollows and the threat of egg destruction by other eclectus parrots may explain this extreme guarding behaviour. Reproductive success was low. The combined effects of egg and chick loss to conspecifics and predators, brood reduction and flooding of hollows from heavy rain meant that only 18% of eggs and 27% of clutches produced a fledgling. Over 4 years, reproductive success amongst females was strongly skewed: 39% of females were never successful, and only 29% produced more than one fledgling per year. Eclectus parrots were found to breed co‐operatively with as many as five males feeding a single female at the nest. Multiple mating, involving one female and four males, was observed once. Despite an even sex ratio at fledging, the adult sex ratio was strongly male‐biased, suggesting higher mortality of females. Our data shows that reproductive variance for females is high, and suggests that a shortage of tree hollows and eligible females may enforce co‐operative breeding amongst males.
Assessing the breeding season diet of goshawks Accipiter gentilis: biases of plucking analysis quantified by means of continuous radio‐monitoring
Authors: Rutz Christian
Published: February 2003

Plucking analysis is a standard method for assessing the breeding season diet of goshawks Accipiter gentilis. Results may be biased, however, due to differences in the detectability of remains of certain prey species and to selective prey transportation by hawks. This study investigated prey choice of three goshawk breeding pairs in the city of Hamburg, Germany, during 1997–99. Predation data obtained by continuous radio‐monitoring of the adult males were used to quantify biases of simultaneous plucking analyses, which were conducted in the nesting territories of the corresponding breeding pairs. A comparison of estimated average food requirements with actual biomass intake observed in two of the monitored goshawks (with sufficient sample sizes) indicated that it was possible to record virtually all kills that occurred during tracking sessions. Therefore, radio‐tracking data could be used to evaluate the accuracy of plucking analysis. Comparisons showed that the proportions of small birds and of feral pigeons Columba livia f. domestica were underestimated by the scanning method by 10% and 13%, respectively. The latter finding was unexpected as pigeons have large, conspicuously coloured feathers that are easy to detect. However, as goshawks plucked large prey more thoroughly at the capture site than smaller prey, a comparatively small number of their feathers were present in the nesting areas. This source of bias in plucking analysis has passed unnoticed in previous studies. It may have important implications for the interpretation of results of future projects that aim to estimate predation rates in goshawks and other bird‐eating raptor species.
Chemical communication in the giant panda (Ailuropoda melanoleuca): the role of age in the signaller and assessor
Authors: White A. M. , Swaisgood R. R. , Zhang H.
Published: February 2003

As a solitary species, giant pandas Ailuropoda melanoleuca appear to use chemical signals to maintain a communication network with individuals in the community with whom they have little direct contact. Chemosensory discrimination abilities undoubtedly play a large role in determining the efficiency of this communication system. The hypothesis that pandas could discriminate the age of the signaller was tested by presenting subjects with a simultaneous choice test between odours collected from adult and subadult donors. Twenty‐eight pandas were tested with three types of stimuli: male urine; male anogenital gland secretions; female urine. The results indicate that individuals from both age classes readily discriminate between adult and subadult odours emanating from all three odour types, showing a pronounced investigatory preference for adult odours in all cases. Female reproductive condition influenced general responsiveness to male odours, but did not significantly alter adult/subadult discrimination patterns. The prevalence of overt discrimination across odour types and age classes suggests an important and multifunctional role for this ability, and highlights the importance of studying chemical communication at all developmental stages. It is proposed that these results may be explained in part by: (1) assessment of competitive ability, which correlates with the age class of the signaller; (2) identification of potential mates that have attained reproductive maturity.
Correlations between call frequency and ear length in bats belonging to the families Rhinolophidae and Hipposideridae
Authors: Huihua Zhao , Shuyi Zhang , Mingxue Zuo , Jiang Zhou
Published: February 2003

Echolocation calls of 10 species of rhinolophid and four species of hipposiderid bats were recorded in China. Close negative relationships were found within Rhinolophidae and Hipposideridae between call frequency and ear length. Multiple regression and residual analysis were used to evaluate the influences of forearm length and ear length on call frequency and ear size. Ear length proved to be a more important morphological parameter influencing the call frequency in rhinolophids but not in hipposiderids. Ears are largely shaped by echolocation calls in both families. The influence of body size on ear size was significant in rhinolophids but not in hipposiderids, and the enlarged ears of rhinolophids correlated with the lower frequencies that rhinolophids used relative to larger body size.
Twice every second year: reproduction in the pig‐nosed turtle, Carettochelys insculpta, in the wet–dry tropics of Australia
Authors: Doody J. Sean , Georges Arthur , Young Jeanne E.
Published: February 2003

The reproductive biology of female pig‐nosed turtles Carettochelys insculpta was studied for 4 years in the wet–dry tropics of northern Australia. Females matured at around 6 kg body mass (38.0 cm curved carapace length, 30.5 cm plastron length). Turtles produced egg sizes and clutch sizes similar to that of other turtle species similar in size. Turtles reproduced every second year, but produced two clutches within years, about 41 days apart. Thus, it appeared that females were energy limited, possibly due to the low available energy content of the dry season diet (aquatic vegetation). Life‐history theory predicts that some costly behaviour associated with reproduction exists, such that by skipping years turtles could reduce that cost and put the savings into future reproduction. Previous work revealed no behaviour associated with reproduction in the population. Within years, clutch mass did not differ between early (first) and late (second) clutches. However, early clutches tended to have more eggs per clutch but smaller eggs than late clutches, a new finding for turtles that has been demonstrated in lizards and other animals. Because the study spanned both years with ‘big’ and ‘small’ wet seasons, we were able to examine how the magnitude of the wet season influenced reproductive characteristics. Following big wet seasons, turtles produced larger, heavier, and more eggs per clutch than they did after small wet seasons. Relationships among body size, egg size and clutch size were evident after two big wet seasons but not apparent after two small wet seasons. Collectively, annual variation in reproductive characteristics and current life‐history theory suggest that a big wet season is a time of high energy accumulation for the turtles.
Evolutionary maintenance of sexual dimorphism in head size in the lizard Zootoca vivipara: a test of two hypotheses
Authors: Gvozdík Lumír , Van Damme Raoul
Published: February 2003

Zootoca vivipara is a small lizard that shows sexual dimorphism in head size. Males have larger heads than females of the same body size. By observing matings and aggressive interactions between males in the laboratory, we investigated whether this sexual dimorphism could be the result of intra‐ and/or intersexual selection. Winners of male–male interactions had larger heads than losers. During mating attempts, males with larger heads succeeded in grasping a female faster than males with smaller heads. It follows that head size in Z. vivipara may affect male reproductive success both through intrasexual competition (fighting ability) and through intersexual selection (grasping ability). This suggests that sexual selection may be the cause for the sexual dimorphism in head size in this species.
Demographic and genetic structure of fossorial water voles (Arvicola terrestris) on Scottish islands
Authors: Telfer S. , Dallas J. F. , Aars J. , Piertney S. B. , Stewart W. A. , Lambin X.
Published: February 2003

The distribution of fossorial water voles Arvicola terrestris on 15 small islands in the Sound of Jura, Argyll, Scotland, was established and populations were characterized in terms of size, structure and genetic composition (12 microsatellites). The results are compared with similar data from four metapopulations of riparian water voles in mainland Scotland. Water voles occurred on six islands, one of which was occupied in 1994, but not on two islands occupied during the 1960s. Probability of occupancy was significantly associated with proximity to the nearest occupied island. Unlike voles on the mainland, which occupy fragmented patches of exclusively riparian habitat, voles on islands were fossorial and occupied large areas of continuous habitat. Spring population sizes were c. 10 times higher on the islands than colonies of mainland metapopulations. Individuals from three islands were genotyped and these populations had 50% lower levels of microsatellite polymorphism than the mainland metapopulations. Rates of inferred contemporary dispersal among islands separated by 1 km or more of sea were very low, according to large differences among islands in genetic composition, proportions of coat colour types and incidence of skin infection. None the less, the long‐term persistence of the island populations is likely to depend on such dispersal. Comparisons between island populations and mainland metapopulations indicate that in both fragmented systems the level of dispersal is the primary factor influencing genetic structure. The low genetic variability in the island populations may reflect either past historical events (founder effect and genetic drift) or present ecology (lack of immigration in closed and temporally fluctuating populations).
An improved topographic database for King George Island: compilation, application and outlook
Authors: Braun Matthias , Simões Jefferson C. , Vogt Steffen , Bremer Ulisses F. , Blindow Norbert , Pfender Marion , Saurer Helmut , Aquino Francisco E. , Ferron Francisco A.
Published: February 2003

A new topographic database for King George Island, one of the most visited areas in Antarctica, is presented. Data from differential GPS surveys, gained during the summers 1997/98 and 1999/2000, were combined with up to date coastlines from a SPOT satellite image mosaic, and topographic information from maps as well as from the Antarctic Digital Database. A digital terrain model (DTM) was generated using ARC/INFO GIS. From contour lines derived from the DTM and the satellite image mosaic a satellite image map was assembled. Extensive information on data accuracy, the database as well as on the criteria applied to select place names is given in the multilingual map. A lack of accurate topographic information in the eastern part of the island was identified. It was concluded that additional topographic surveying or radar interferometry should be conducted to improve the data quality in this area. In three case studies, the potential applications of the improved topographic database are demonstrated. The first two examples comprise the verification of glacier velocities and the study of glacier retreat from the various input data-sets as well as the use of the DTM for climatological modelling. The last case study focuses on the use of the new digital database as a basic GIS (Geographic Information System) layer for environmental monitoring and management on King George Island.
Postembryonic development of Apseudes heroae and Allotanais
hirsutus (Tanaidacea, Crustacea) in Magellanic and sub-Antarctic waters
Authors: SCHMIDT ANJA , SIEGEL VOLKER , BRANDT ANGELIKA
Published: February 2003

Apseudes heroae Sieg, 1986 (Family Apseudidae) and Allotanais hirsutus (Beddard, 1886)
(Family Tanaidae) are common Tanaidacea of the southern Magellanic region. The aim of the investigation
is to elucidate the postmarsupial development of these tanaid species that differ in their biogeography.
Population structures are analysed from size frequency data and from different postembryonic stages of
specimens collected in the Atlantic entrance of the Beagle Channel and from the Atlantic continental slope
to the south-east. The population of Apseudes heroae shows three age groups, the one of Allotanais hirsutus
probably at least three. Some large specimens indicate that the latter sub-Antarctic species might reach an
age of several years. Both species are probably gonochoristic, and protandric hermaphroditism was not
observed. The fecundity of Apseudes heroae and Allotanais hirsutus was analysed. No significant
correlation could be found between cephalothorax width and egg number or number of larvae. For both
species hypothetical life cycles are reconstructed. As sub-Antarctic temperatures are low and seasonality is
strong in the Magellanic region, it is possible that these species are reasonably adapted in reproduction as
shown in some polar species of Isopoda and Cumacea.
Energy content of mesopelagic fish from Macquarie Island
Authors: TIERNEY MEGAN , HINDELL MARK A. , GOLDSWORTHY SIMON
Published: February 2003

The water and calorific content of fifteen species of mesopelagic sub-Antarctic fish from
Macquarie Island were determined. Mean percent water content was 69–82%. Calorific content was highly
variable between species, especially in the Myctophidae, where it ranged between 22.6–59.3 kJ·g−1 dry
weight. The water and calorific content varied with size class within a species, with the smallest size classes
generally having the lowest water content but highest calorific content. These values will be useful for future
assessment of energetic transfer between trophic levels and energetic modelling of Southern Ocean
ecosystems.
Satellite tracking of icebergs in the Weddell Sea
Authors: GLADSTONE R. , BIGG G.R.
Published: February 2003

Small to medium sized icebergs (200 m to 10 km across) in two areas of the Weddell Sea were
tracked using satellite-borne Synthetic Aperture Radar (SAR) from 22 January–21 February 1994 and
29 January–25 February 1992 respectively. The westward mass flux of icebergs in the Antarctic Coastal
Current was estimated at the eastern entrance to the Weddell Sea as being 50–70 Gta−1. A large contrast was
found between observations over the narrow shelf here and the off-shelf area. The latter region had very
much reduced iceberg density, and the bergs moved with slower and less coherent velocities compared with
the fast, but narrow (10–20 km wide) flow in the Coastal Current. This region is a promising site for the
monitoring of decadal trends in iceberg fluxes. The second study area in the south-western Weddell Sea
showed iceberg motion consistent with non-contemporaneous observations of tagged icebergs, with steady
flow parallel to the shelf-ice edge, at significantly lower densities and speeds than in the Coastal Current but
almost double that observed off-shelf in the eastern Weddell Sea. We also suggest that shipboard
observations of icebergs need careful analysis to avoid their over-estimating true iceberg concentrations by a
substantial amount.
Lipid and fatty acid composition of the mantle and digestive gland
of four Southern Ocean squid species: implications for food-web
studies
Authors: PHILLIPS KATRINA L. , NICHOLS PETER D. , JACKSON GEORGE D.
Published: February 2003

Lipid content, lipid class and fatty acid composition of four Southern Ocean cephalopod species –
the myopsid Sepioteuthis australis and three oegopsids, Gonatus antarcticus, Moroteuthis robsoni and
Todarodes spp. – were analysed. The lipid content of the digestive gland was consistently greater than that of
the mantle, and was an order of magnitude greater in oegopsid species. The lipid class and fatty acid
composition of the mantle and digestive gland also differed markedly in each species. Digestive gland lipid
is likely to be of dietary origin, and large amounts of lipid in the digestive gland of oegopsids may
accumulate over time. Thus the digestive gland is a rich source of fatty acid dietary tracers and may provide
a history of dietary intake. However, the absolute amount of dietary lipid in the digestive gland of oegopsid
species exceeds the absolute lipid content of mantle tissue. Therefore the overall lipid “signature” of an
oegopsid may more closely resemble its prey species rather than its mantle tissue. When lipid techniques are
used in dietary analysis of teuthophagous predators, squid may not be represented by a unique signature in
analyses and their importance in the diets of predators may be underestimated.
Effect of a shore-based sampling programme on
Notothenia coriiceps populations
Authors: CASAUX R.J. , BARRERA-ORO E.R.
Published: February 2003

The effect of an intensive sampling programme on an inshore population of Notothenia coriiceps
was studied at Potter Cove, South Shetland Islands, by comparing catch data taken in successive summers of
1992/93 to 1994/95 at one specific zone (site 1) with those taken in the 1994/95 summer at two close but not
previously sampled zones (sites 2 and 3). The fish were caught with trammel nets under similar sampling
conditions (depth, net measurements, bottom type). In site 1, a decline in length (TL) of the fish was
observed throughout the whole period. The fish from sites 2 (mean = 32.4 cm) and 3 (mean = 31.8 cm)
exhibited no significant differences in mean length. They were larger (P = 0.07) than those from site 1
caught in the summers of 1994/95 (mean = 28.8 cm) and 1993/94 (mean = 30.2 cm), but were similar in size
to those sampled in the summer of 1992/93 (mean = 31.7 cm), just when the sampling programme started in
site 1. Although alternative hypotheses to explain the results are discussed (e.g. random error, strong
recruitment), it is suggested that the size variations of the fish sampled at site 1 are due to intensive sampling
effort carried out throughout this study at that specific zone in Potter Cove.
Evidence of dense water overflow on the Ross Sea shelf-break
Authors: BERGAMASCO A. , DEFENDI V. , ZAMBIANCHI E. , SPEZIE G.
Published: February 2003

This paper presents the results of the analysis of hydrological data of a 5-day mesoscale
experiment (53 CTD casts) conducted during the XIIIth Italian Expedition to Antarctica (1997–98 cruise) in
the framework of the CLIMA (Climatic Longterm Interaction for the Mass balance in Antarctica) Project of
the Italian National Programme for Antarctic Research (PNRA). The experiment site was chosen for
studying the dense water overflow in relation to the shelf-break in the central Ross Sea, after a large-scale
synoptic survey, aimed to detect the general hydrological characteristics of the basin. A classical θ/S analysis
was carried out for better understanding of the shelf-slope connection and the interactions between the water
masses of this zone: the Circumpolar Deep Water (CDW) coming from the oceanic domain and the Ice Shelf
Water (ISW) spreading from the Ross Ice Shelf (RIS) edge. Our results show the evidence of an overflow of
dense water, originated on the continental shelf, on the shelf-break. This supercold water signal is found on
the continental slope down to 1200 m depth. The shape of this tongue of modified ISW, whose thickness
reaches up to 100 m, is very narrow, suggesting that the overflow occurs in very localized areas.
Mid-Holocene macrofossil-bearing raised marine beaches at
Potter Peninsula, King George Island, South Shetland Islands
Authors: DEL VALLE RODOLFO A. , MONTALTI DIEGO , INBAR MOSHE
Published: February 2003

A 2.7 m thick mid-Holocene sedimentary succession composed of alluvial fan and marine beach
deposits is exposed at 14.4–17.1 m above sea level (a.s.l.) on the south-eastern coast of Potter Peninsula,
King George Island (South Shetland Islands, Antarctica). The raised marine beach deposits contain a
subfossil assemblage that includes remains of Adélie (Pygoscelis adeliae) and gentoo (P. papua) penguins,
skua (Catharacta sp), seals (elephant seal Mirounga sp), and seaweed fragments. The palaeontological and
palaeogeographical evidence allows us to infer that penguin rookeries were active on high cliffs of the Potter
Peninsula during the marine beach sedimentation, which is dated to c. 4540–4450 reservoir-corrected
14C yr BP on the basis of radiocarbon dating on penguin bones. The data presented in this paper are in
agreement with the Holocene palaeoenvironmental chronology known from Potter Peninsula, and suggest
that marine birds and seals inhabited the coastal areas of King George Island probably during a mid-
Holocene period of seasonally open marine conditions, which may coincide with a cooling period around
Antarctica estimated from ice core records between 8000–4000 yr BP that preceded the “climate optimum”
in the Antarctic Peninsula (4000–3000 yr BP).