Geese have to satisfy the high energy demands of flight with a low-energy and bulky food. When feeding on food items that are concentrated and widespread, as is the case in geese, an individual's instantaneous intake rate is largely determined by its bite size. Inter-individual variation in bite size was measured in barnacle geese Branta leucopsis, with the hypotheses that bite size would scale with (sward height)a, where 0<a<1, and (bill length)b, where b=3.0, and that there would be a positive interaction between these explanatory variables. Using a generalized linear mixed modelling analysis, bite size was found not to vary over the measured sward heights, whilst bite size was found to scale with bill length to the power b=14.24 (SE=2.05). There was no significantly detectable interaction between these terms, indicating that barnacle geese with longer bills had larger bite sizes over the full range of sward heights studied. Bill length scaled with body mass to the power 0.21 (SE=0.01). Combining this with the scaling of bite size to bill length, we conclude that bite size scales with body mass to the power 2.99. Our results suggest that larger barnacle geese have a disproportionately larger bite size than smaller geese, which may explain the fitness advantages of larger geese observed in other studies. However, smaller geese may resist this selection pressure by selectively consuming more nutritious plant parts or altering their bite rates.

The ontogeny of the musculature and segments of the antennule of Heterocypris incongruens (Ramdohr, 1808) is documented. The musculature of the antennule of the juveniles indicates that during ontogeny the additional segments originate by existing segments dividing. Previously presented hypotheses are tested with these new data. Smith & Martens' (2000) hypothesis on the development of the antennule of Eucypris virens (Jurine, 1820) is supported and is expanded to cover other groups. There are five segments in the early juveniles of most species and some of these divide to form new segments during ontogeny. Additionally, some segments fuse together, and some segments divide and then fuse together again. Most divisions of segments produce two true segments, rather than annulations or secondary joints, but one species shows evidence of an annulation in the antennule.

From 1515, the rhinoceros was well known in Europe through a woodcut by Albrecht Dürer, showing an armour-plated animal from India with one horn on the nose and a spurious ‘Dürer-hornlet’ on the shoulders. When the first reports of the rhinoceros from Africa spread in the 17th century, it was not differentiated from the prototype, although it had a smooth skin and two nasal horns. Parsons in 1739 recognized differences between rhinos in Asia and Africa, but could not clearly separate them as two forms. Linnaeus based Rhinoceros bicornis on a skull from India with a second horn added by a trader. Camper in 1780 provided first anatomical proof for the existence of two species of rhinoceros distinguished by the number of teeth and horns. In the 19th century, travellers exploring the interior of southern Africa named rhino species according to the shape and size of the two horns, known as the Rhinoceros simus of Burchell, the unicorn of Campbell, the keitloa of Andrew Smith and the Mohoohoo of Oswell. Around 1900, with an increase of observations from the entire African continent, only two species were recognized, known as black rhino Diceros bicornis and white rhino Ceratotherium simum. The black rhino was first seen in captivity in the 1870s, the white rhino in 1944. Their status in the wild is precarious primarily because of illegal hunting for the horn. Continuous protection and management in the field together with research and documentation of their biology can still achieve their long-term preservation.

Limited resources will inevitably lead to trade-offs between traits. However, trade-offs are not always observed, for a variety of reasons. For example, failure to take into account covariates, and high variation in resource acquisition relative to variation in resource allocation, can obscure the underlying trade-off. In the present paper, the trade-off between offspring size and number was examined in the common lizard Lacerta vivipara. Size–number trade-offs can arise for two different reasons, limited food resources or space constraints. There was no significant trade-off between size and number of young under natural conditions, whereas females captured before ovulation and provided with excess food under laboratory conditions showed a negative correlation between clutch size and offspring size. Food supplementation did not significantly increase reproductive output compared to natural conditions and, thus, the presence of a trade-off under ad libitum conditions was not the result of space limitation in the female reproductive tract. The variance ratio between allocation to investment, however, was twice as high for females ovulating in the laboratory, suggesting that the existence of a trade-off under ad libitum conditions could be a result of less variation among females in resource allocation.

Measurement and dissection of 97 museum specimens provided information on morphology, food habits, and reproduction in the colubrid snake Symphimus mayae. This medium-sized (<910 mm total length) diurnal species from the Yucatán Peninsula is an inhabitant of lowland xerophytic habitats, and an orthopteran dietary specialist. Sexual dimorphism is evident in relative tail length, head length, and numbers of subcaudal scales, but not in the number of ventrals, and males and females attain similar adult body sizes. Symphimus mayae feeds almost exclusively on orthopteroid insects, principally katydids (Tettigoniidae) and crickets (Gryllidae). These taxa jointly accounted for >50% of the total number of prey items recovered from stomachs and had been eaten by >70% of the snakes examined, with little intraspecific or seasonal variation. Other, less frequently used prey groups are (in order of relative importance), stick insects, mantids, Jerusalem crickets, grasshoppers and spiders. All size classes of snakes eat orthopterans, but stick insects are consumed predominantly by adults (>300 mm SVL), and mantids exclusively by large adults (>420 mm SVL). More than 55% of individuals from monthly samples contained recently ingested food, suggesting that feeding in S. mayae occurs year-round and is not significantly curtailed by the local dry season. Reproduction is probably annual, although it does not occur in all females every year, and a single clutch of two to four eggs is produced with oviposition and hatching timed to the wet season.

Dry season diets and habitat use of increasing populations of Asian elephants Elephas maximus and greater one-horned rhinoceros Rhinoceros unicornis in the Babai Valley of Royal Bardia National Park, Nepal, are described, and an assessment is made of the potential for competition between them. The diets, analysed by microhistology, were different, with a similarity index of 37.5%, and with different grass/browse proportions: the rhino diet consisted of 63% grass and 28% browse; that of elephants was 24% grass and 65% browse. A tallgrass floodplain grass, Saccharum spontaneum, was the plant most eaten by rhinos, whereas elephants consumed a large proportion of bark of Bombax ceiba and Acacia catechu, as well as several browse species not eaten by rhino. The habitat use of elephants was determined by dung-counts within 30 km of 20-m wide belt transects, while that of rhino was taken from an earlier study. Elephants used a wider range of habitats than rhino, but two types, the tallgrass floodplain and khair–sissoo forest, were preferred by both species simultaneously. While elephants used the abundant sal forest extensively, rhino strongly avoided this habitat. Densities of both species were low at the time of study (<0.5 animals/km2), but their numbers are expected to increase markedly in coming years. Because available habitats for expansion are limited, this may lead to competition. Rhino might then become the weaker species, as elephants are more flexible in their ranging and foraging activities. The tallgrass floodplain habitat and its important forage grass S. spontaneum may then become the critical resources.

The ability of a living organism to perform specific actions such as prey capture or predator avoidance is a critical feature that should affect individual fitness. Snakes have an elongate morphology that lacks the regional variation associated with girdles found in limbed vertebrates. In this context, this group offers interesting opportunities to study specific forms and functions. In this study, we examined musculature in a medium-sized boid snake, the Colombian rainbow boa Epicrates cenchria maurus, by combining two methods: magnetic resonance imaging (MRI) and calliper measurements after axial palpation. The MRI demonstrated an important development of epaxial musculature consistent with the predatory mode of constriction. We showed that MRI and palpation data were strongly correlated, indicating that musculature is an easily measurable phenotypic feature in the studied species. The calliper method was then applied in combination with assessments of physical performance (constriction and defence capabilities) in a group of snakes after a prolonged fast and again after a re-feeding period. A clear relationship was detected between dorsal musculature and both maximal traction and constriction forces. Re-feeding significantly increased dorsal musculature and traction capabilities. While musculature assessments are classically difficult to achieve among tetrapods, this study suggests that snakes are interesting models for examining variation in musculature and performance in natural and experimental conditions.

Life-cycle polymorphism within single populations has been reported in a variety of arthropods including insects and spiders. Most individuals within polymorphic populations overwinter in a species-specific stage, which plays an important role in synchronizing the life cycle within a population. Here, we report the first case of a life-cycle polymorphism in spiders that differs in the overwintering stages between two coexisting cohorts, and test if the variation in timing of these two cohorts (autumn and spring maturing) results in expected differences between key life-history characteristics, namely size at maturity, adult survival and reproductive output. A 3-year mark and recapture study in the floodplain of the Avon River, south-east Australia, allowed the calculation of adult survival and recapture probability (Jolly–Cormack–Seber model) for the two cohorts in three consecutive generations of the riparian wolf spider Venatrix lapidosa (McKay). In the autumn maturing cohort, adult survival was time dependent with high survival rates during the winter months, but there was no difference between sexes. In contrast, survival was constant over time in the spring maturing cohort, but was higher for females than for males. Males and females of the autumn maturing cohort were significantly larger than those of the spring maturing cohort. More adverse conditions in the juvenile development of spring maturing cohort are likely to account for this difference. In addition, earlier maturation and reproduction of females of the spring maturing cohort in comparison to the winter maturing spiders may increase the survival of larger offspring during the upcoming winter. Propensity to oviposit was significantly lower in females of the autumn maturing cohort than in the spring maturing cohort, as spiders of the autumn maturing cohort are exposed to adverse winter conditions before reproduction. The life-cycle control of both cohorts seems to be governed by different mechanisms: diapause control of reproduction through delayed vitellogenesis of the ovaries in the autumn maturing cohort, and diapause control of juvenile development in the spring maturing cohort. Both mechanisms have previously been suggested for wolf spiders but have not been reported for the same species.

The behavioural use of rock crevices by rock hyrax Procavia capensis was essential in avoiding harsh environmental conditions during summer. Foraging was the most dominant above-ground behaviour exhibited by rock hyrax during summer. Most ambient temperatures in the early morning of summer fell within the rock hyrax thermoneutral zone, which enabled the animals to forage without the need for prior heating from a solar energy source. Basking was an essential behaviour displayed by rock hyrax in winter. The low quality and scarce food source may be inadequate to meet the metabolic requirements of rock hyrax at low ambient temperatures. It therefore seems that basking is not only an energy conservation mechanism but also essential for the survival of rock hyrax during winter. Juvenile rock hyrax have a higher surface area to volume ratio and are more vulnerable to low ambient conditions than adults. As a result they displayed a different behaviour pattern to adult rock hyrax during winter. Juveniles required larger amounts of food to meet their energetic requirements, while adults spent greater amounts of time basking. The extent to which rock hyrax meet energetic requirements depends on the interaction of ambient temperature, food availability, food quality and foraging efficiency in the presence of predators. The extent to which each of these factors influenced behaviour differed on a daily and seasonal basis.

During the past 50 years the number of badgers (Meles meles) in Denmark has declined by c. 50%. To assess the genetic consequences of the demographic decline, six DNA-microsatellite loci were used to analyse 139 badger tissue-samples, which were collected in 1995–98 from three zones (1, 2 and 3) in Jutland (Denmark). Results from contemporary samples were compared to data obtained from DNA extracted from teeth belonging to 39 badgers collected from zones 1 and 2 in 1957–66. The microsatellites showed a low to moderate polymorphism, and the within area genetic diversity (HE) was relatively low (0.308≤HE≤0.441) as compared to other carnivores and mustelids. Genetic differentiation among the three recent sampling zones was significant (FST=0.072, P<0.0001). The FST values between the two recent (FST=0.092, P<0.0001) and the two historical samples (zones 1 and 2; FST=0.073, P<0.0001) were significant and similar. The HE and FST of the recent and historical zones were not significantly different (P>0.05). Despite the drastic recent decline, Danish badgers did not show apparent signs of genetic bottlenecks in both recent and historical samples. The use of molecular techniques which allowed us to work with small amounts of degraded DNA extracted from old teeth, allowed us to exclude the hypothesis that genetic differentiation between zones 1 and 2 was owing to a barrier, which has appeared in the last 50 years. Furthermore, the low genetic variability and therefore the relatively high genetic differentiation shown by Danish badgers were also shown not to be the result of the recent drastic population decline.

Variation in life history is a central key to understanding population dynamics, and density dependence and climate are important factors in shaping life-history variation in ungulates. Early growth is often sensitive to adverse conditions and this may in turn affect juvenile survival and age at first reproduction. We report variation in body weight of 5079 reindeer Rangifer tarandus from North Ottadalen, a very productive reindeer area in Norway, sampled over 14 years in the period 1967–1989. The North Ottadalen reindeer herd was established in 1964 from a winter herd of some 500 semi-domestic reindeer, and allowed to grow to a peak of over 3300 reindeer in 1974, after which increased harvest decreased the population size. The proportion of lactating yearling females varied between 0% and 50%. Lactating females had lower autumn body weights than non-lactating females. A decline in body weight with age, i.e. senescence, was evident in both males and females from around 7 to 9 years of age. Body weights of all age and sex groups as well as the proportion of yearling females lactating decreased over time, and more so in younger than older males, although the population size declined markedly after the population peak in 1974. We found no effect of the North Atlantic Oscillation or local weather on body weight. The possible causes of the marked decline in performance with time in the North Ottadalen reindeer herd are discussed, and it is suggested that this may be related to the transition from being managed as semi-domestic to wild (i.e. hunted).

This study investigated burrow use and ranging behaviour in the southern hairy-nosed wombat Lasiorhinus latifrons in semi-arid South Australia. Sixteen adult wombats were fitted with radio transmitters and monitored monthly from July 2001 to February 2002. Wombats generally used between one and five warrens, preferred large warrens with a greater number of entrances and showed a preference for one or two warrens. Across the study period there was no apparent change in burrows used within warrens. Radio-tracking indicated that animals spent very little time above ground (26% of 1115 night-time fixes), centred their activity around their preferred warrens, and moved, on average, 99 m/h and 221 m/night. Mean home-range size, estimated using minimum convex polygons and the harmonic mean method from location data, obtained through triangulation, and daytime warren fixes, ranged from 1.3 to 4.8 ha. Home-range size was similar between males and females and home ranges overlapped substantially. The data highlight the importance of burrows to southern hairy-nosed wombats in shaping their home ranges. It seems likely that the use of burrows and a specialized diet are important energy saving strategies for this species in such unpredictable regions of South Australia.

The allometric relationship between body mass and burrow cross-sectional area for burrowing animals holds across greater than six orders of magnitude variation in body mass, and includes species separated by >500 million years of evolution from two phyla (Arthropoda and Chordata), seven classes (Arachnida, Insecta, Malacostraca, Osteichthyes, Amphibia, Reptilia, and Mammalia) and both terrestrial and marine habitats. Only birds, which construct relatively large burrows, and vermiform animals, which construct relatively narrow burrows, are separated from the remaining burrowing species. No difference is found between fossorial (burrowing animals that forage beneath the soil surface) and semi-fossorial (burrowing animals that forage terrestrially) mammals, suggesting that subterranean foragers do not modify burrow cross-sectional area to increase energy yields. However, solitary fossorial mammals do construct significantly larger nest chambers than semi-fossorial and colonial fossorial mammals. These large nest chambers probably assist in maintaining body temperature by providing a better thermally insulated microenvironment. This offsets the thermoregulatory problems faced by these animals, which are characterized by low, labile body temperatures and poor thermoregulatory ability. Colonial fossorial mammals, on the other hand, construct nest chambers that are the same relative size as those constructed by semi-fossorial mammals and probably maintain homeothermy by huddling with endothermic nest-mates.

Variation in size of home range is among the most important parameters required for effective conservation and management of a species. However, the fact that home ranges can vary widely within a species makes data transfer between study areas difficult. Home ranges of Eurasian lynx Lynx lynx vary by a factor of 10 between different study areas in Europe. This study aims to try and explain this variation in terms of readily available indices of prey density and environmental productivity. On an individual scale we related the sizes of 52 home ranges, derived from 23 (9:14 male:female) individual resident lynx obtained from south-eastern Norway, with an index of density of roe deer Capreolus capreolus. This index was obtained from the density of harvested roe deer within the municipalities covered by the lynx home ranges. We found a significant negative relationship between harvest density and home-range size for both sexes. On a European level we related the sizes of 111 lynx (48:63 male: female) from 10 study sites to estimates derived from remote sensing of environmental productivity and seasonality. A multiple linear regression model indicated that productivity of the study site had a clear negative relationship with home-range size. At both scales, sex emerged as a significant explanatory variable with males having larger home ranges than females. In addition, the size of male home-ranges increased faster with decreasing prey density than for females. These analyses support widely held predictions that variation in home-range size is due to variation in prey density.

Edge drilling is a form of predation in which a predatory snail excavates a hole at a point along the margin of the closed valves of a bivalved animal. We tested the hypothesis that edge-drilling attacks by the predatory snail Chicoreus dilectus on its clam prey Chione elevata shorten the duration of the predation process relative to the alternative behaviour of drilling through the prey's shell wall away from its edges. The time required to complete an edge-drilling attack was on average about three times less than when prey were attacked through the shell wall. This improvement in predation speed was a function of the thickness of the prey's shell at the point of attack. We suggest that owing to the shorter length of time required to kill prey, the edge-drilling behaviour may be selectively advantageous in environments where enemies are abundant, especially competitors that might attempt to steal prey. Behaviours that speed up the predation process may create opportunities for more effective exploitation of available prey resources in highly competitive environments.

Yellow-bellied marmots Marmota flaviventris were live-trapped and marked in the East River Valley of Colorado from 1962 to 1998. For females, static life tables were calculated each year from 1967, when ages were well known, to 1997. Population density was determined, and from life tables calculations were made of: survivorship of young, yearlings and adults; percentage of females producing litters; mean and variance of litter size; net reproductive rate (Ro); and generation length. From climate records a set of 14 annual weather variables was developed that described temperature, precipitation and lengths of growing season and winter. Data from 1981 and 1996 were not used since weather data contained extreme outliers in date of last snow cover. Univariate correlation matrices were calculated among weather variables, among demographic variables, and between weather and demographic variables. Mean temperature in 24 of 29 years was cooler than long-term average temperature. Generation length increased during the years of the study. Weather data were used as independent variables with each dependent demographic variable to calculate nine multiple correlation and regression models. Models explained from 0% to 58% of the variation in demography. Significant factors in each model were mostly interpreted as affecting availability of energy necessary for successful hibernation and reproduction.

The relationships between population abundance, body size, food habits and ecological guild (aquatic, terrestrial, arboreal, and fossorial) of snake communities are studied in three different habitats (swamp-rainforest, mangrove forest and derived savanna) of southern Nigeria, West Africa. There were slightly positive relationships between body size and population abundance of snakes in the three study habitats of tropical Nigeria, but statistical significance was reached only in the swamp-rainforest habitat. The population abundance of the various species was not related to either their food habits or their ecological guild in any of the three study areas. The possible reasons explaining these patterns are discussed. In general, there is little congruence between our data and the popular ‘energetic equivalence rule’ hypothesis.

The European mink Mustela lutreola is the focus of extensive conservation programmes whereas the American mink M. vison is exotic in Europe and a possible cause of European mink decline. Since both species, together with the European polecat M. putorius have similar hair and produce similar faeces, molecular techniques are essential for reliable species identification when disturbance is not appropriate. In this report a simple, cheap and reliable molecular method for the genetic distinction of mink is provided based on the amplification of the microsatellite locus Mel08 that results in a longer PCR product (436 bp) in American mink than in other mustelid species, such as the European mink (221 bp) and the European polecat (221 bp). Sequencing these PCR products revealed, in the microsatellite-flanking region of American mink, a CAN-SINE insertion of 213 bp that was absent in 22 species of the Canoidea superfamily tested. When the Mel08 PCR product is cut with restriction enzyme AciI and then run in an agarose gel, the restriction pattern observed is different in the three Mustela spp. The method was successfully tested with DNA amplified from a large sample of hair roots, thus making it suitable for non-invasive sampling.

Sex ratios of the American snapping turtle Chelydra serpentina are female-biased at cool temperatures, male-biased at moderate temperatures, and only females are produced at warm temperatures. The laboratory incubation of eggs at several constant temperatures yields patterns of skewed sex ratios. In this study, incubated eggs represented regional samples of C. serpentina from six different latitudes. The sample from the highest latitude yielded male-biased sex ratios across the broadest range of cool temperatures. This male-biased zone and those of the other five samples collectively contributed to a nested arrangement that is approximately symmetrical around a temperature of 24.5°C. Two indices of temperature-dependent sex determination (TSD) patterns (MF pivotal temperature, width of the male-biased zone) were significantly associated with latitude and with published data on several climatic variables (e.g. sunshine and rainfall). At high latitudes, females nest in exposed locations, locally the warmest places. At low latitudes females place their nests in shaded locations. Such nest site selection renders high latitude nests warmer than low latitude nests, even if only intermittently. Given that constant conditions show faster embryogenesis in high vs low latitude eggs, exposed nest sites seem to be an additional adaptation to hasten embryogenesis in high latitude nests. At low latitudes, shading prevents nests from overheating. We propose that a trade-off between evolution, (1) to balance sex ratio and (2) to maintain male-biased sex ratios in a temperature range that favours male fitness, leads to the observed arrangement of concentric TSD patterns centred around male production at 24.5°C.

The timing of implantation, duration of gestation and energetic costs associated with foetal development were examined in the north-west Atlantic grey seal Halichoerus grypus. Implantation occurs between 5 and 8 May. Active gestation lasts for 259–272 days and the duration of suspended development is 78–91 days. The duration of active gestation was slightly shorter among north-east Atlantic grey seals (238–255 days), while suspended development was longer (95–112 days). The rate of foetal growth increased in August, 3 months after attachment, until mid December when it began to slow once again, c. 1 month before parturition. During August, the placenta to foetus mass ratio was about 0.3, but declined to around 0.07 near birth. Foetal energy density increased rapidly reaching asymptotic levels of 22.6 kJ g−1 (dry weight) 3–4 months after implantation. Energy density of the placenta changed only slightly throughout gestation increasing from c. 21.7 to 23 kJ g−1 (dry weight) by the autumn. Energy costs associated with foetal growth are c. 648 MJ.