This study investigated how demographic characteristics of black rat snakes Elaphe obsoleta are affected by the length of the active season, and also used the resulting demographic data to determine the proximate factors responsible for male-biased sexual size dimorphism (SSD) in the species. Demographic data collected from 1981 to 1998 in Ontario (ON; 583 males and 588 females) and from 1942 to 1976 in Maryland (MD; 180 males and 150 females) were used to develop growth models with the von Bertalanffy growth equation. Instantaneous growth rates declined significantly with increasing snout–vent length (SVL) in males and females of each population. The growth models predicted age using SVL satisfactorily, but the accuracy of the model decreased significantly with increasing SVL. As predicted, based on the brevity of their active season (ON [ape ] 135 days, MD [ape ] 190 days), rat snakes of both sexes from Ontario had lower and more variable instantaneous growth rates and matured at a more advanced age (ON [ape ] 9 years, MD [ape ] 4 years) than snakes from Maryland. However, the rapid growth and early maturation in Maryland snakes occurred at the expense of longevity (maximum: ON [ape ] 30 years, MD [ape ] 20 years). Slower growth and later maturation will make rat snakes in Ontario less capable of recovering from population declines. Within each population, males grew faster than females. Survivorship for Ontario snakes did not vary by sex, but increased significantly with increasing SVL. The demographic consequence of sex differences in growth was a male-biased sex ratio among larger snakes. Because SSD is a function of males growing faster than females, SSD in black rat snakes is probably a product of sexual selection, suggesting that large size confers a mating advantage in males.

A female platypus Ornithorhynchus anatinus was intensively monitored with the use of video equipment in captivity at Healesville Sanctuary, Victoria, Australia to record feeding and behavioural changes that occurred as a result of only the second successful raising of young platypus (twins) in captivity. These results revealed the female to be inactive (not leaving the burrow) for periods up to 6 days, and mating occurred 15–21 days before eggs were laid. The nest was built over 5 nights between 5 and 9 days before the eggs were laid. The eggs were thought to have been laid during a 4-day period when the female was confined to her burrow. Once the eggs were laid there was a slow initial rate of feeding which sharply rose 20 days after the eggs were laid. The first time the female spent a day away from the young was 39 days after the eggs were laid, after which she decreasingly nested with them until she spent only 8% of the time with them when they emerged from the burrow, 131 and 136 days after the eggs are thought to have been laid. She rarely went in the nest after day 155, suggesting that the lactation period is c. 135–145 days, assuming 10 days for incubation. The time of emergence also corresponded with the peak in the female''s food consumption, which correlates well with the high demands of late lactation, with the daily food intake reaching c. 90–100% of body weight 140 days after the eggs are thought to have hatched. This captive breeding of the platypus has provided the first records of the gestation period, food consumption in relation to breeding stage, the time the female spends with her young during their development, and a partial growth curve of developing platypus.

A 16-year study of wild, unprovisioned sifaka Propithecus verreauxi verreauxi at Beza Mahafaly in south-west Madagascar provides estimates of age-specific fertility, mortality, and dispersal in a population of 426 marked animals, and longitudinal records of individual life histories. Sifaka females give birth for the first time later and live longer, for their size, than mammals in other orders; they also give birth later and continue reproducing longer, for their size, than other primates. Theory postulates that these features, commonly referred to as bet-hedging, evolve in unpredictable environments in association with widely varying infant survival and a trade-off between reproductive effort and adult survival. The climate of south-west Madagascar is highly unpredictable compared to almost all other regions in the tropics with similar average rainfall, and we argue that sifaka females are bet-hedgers par excellence. Male sifaka, in contrast, become reproductively active at an earlier age than females, and are less likely to have long lives than females. The atypical direction of this asymmetry between males and females reflects a ‘slowing down’ of female life histories rather than a ‘speeding up’ of male life histories. Two other unusual features of sifaka biology and behaviour may be linked to the unpredictability of Madagascar's climate: intense local competition between females, and a sex ratio at birth strongly biased in favour of males in most years. In drought years, reproductive females must cope with suddenly intensified resource constraints. This, in turn, may strongly limit the number of ‘breeding slots’ available over the long-term for females.

This paper provides basic information about the breeding biology of four species of Antarctic fulmarine petrels breeding in the Rauer Islands, East Antarctica: Antarctic fulmar Fulmarus glacialoides, Antarctic petrel Thalassoica antarctica, Cape petrel Daption capense, and snow petrel Pagodroma nivea. Timing and duration of the nesting cycle, incubation and nestling periods, and timing of breeding were determined over three consecutive breeding cycles. Comparing these data with those of other populations revealed that the duration of breeding showed little interannual and spatial variation within the four species. The length of the breeding period varied between the species, with incubation period and nesting cycle length positively related to adult body mass. Nestling period length also differed between the species but was unrelated to adult body mass. Breeding period lengths for these fulmarine petrels were shorter than those for other procellarids and albatrosses. Compressed and invariant breeding cycles of Antarctic fulmarine petrels may have evolved in response to a short season which limits breeding and to opportunities presented by highly abundant food sources.

Temporal distribution and composition of ichthyoplankton and their relationships with some environmental variables of Leopoldo's Inlet (Ressaco do Leopoldo) on the upper Paraná River floodplain, southern Brazil, were analysed. Samples were taken from February 1991 to February 1992, and 3480 larvae were collected. The highest density of larvae was observed in November 1991 (36.79 larvae/10 m3) at night (night/day ratio 7: 1). Species composition showed a predominance of Characiformes (80%). There was a high density (4.28 larvae/10 m3) of Bryconamericus stramineus throughout almost the whole study period. The majority of the species were more frequently collected at night. Pearson's correlation indicated a relationship between larval density, temperature, and pluviometric index. Leopoldo's Inlet, whose ichthyofauna is mainly composed of grazing and resident species, shows favourable conditions for fish reproduction and development.

The aim of this study was to investigate the effect of food deprivation on the cardiac activity of two Mediterranean limpets, the exploiter Patella caerulea and the conserver P. rustica, which have different foraging regimes. Heart rate variations were monitored in the two species according to two experimental protocols: (1) starvation/recovery, during which limpets were starved for up to 15 days and then allowed to feed on boulders covered with microalgae; (2) starvation/forced feeding, during which specimens were starved for 11 days and then fed orally with a test (30 mg/ml glucose) or control solution. Increasing starvation time was associated with a significant decline of heartbeat frequency in both species. The decline was comparable in the two species, but heartbeat frequencies in P. rustica were always significantly lower than in P. caerulea. When the limpets were allowed to feed on natural substrates, a rapid increase in heart rate was observed, with frequencies slightly higher than those measured at the beginning of the experiment. No significant difference in heart rate was observed between the two species. Similarly, both in P. caerulea and P. rustica forced feeding caused a recovery of heart rate to pre-treatment levels. The results are consistent with previous findings on the metabolic consequences of food deprivation in gastropods and demonstrate the ability of both species to depress their heart rate when faced with a food shortage. Moreover, a greater regulative ability was observed in P. rustica than in P. caerulea, confirming their status as conserver and exploiter, respectively.

Behavioural and anatomical analyses were undertaken to determine the visual capabilities of a small nectivorous Australian marsupial, the honey possum Tarsipes rostratus. It is proposed that, despite a crepuscular lifestyle and a low visual acuity, vision contributes substantially to the honey possum's perception of its environment. Visual acuity, determined using a discrimination task, revealed a slightly higher performance in daylight (0.63 cycles/degree) than in moonlight and starlight (0.60 cycles/degree). Ultrastructural analysis of the outer retina revealed a rod to cone ratio comparable to that found in diurnal retinae (20:1 in the central retina). Two types of oil droplets were distinguished on the basis of size. The degree of neural convergence was also similar to that found in a diurnal retina, with a ratio of 12 photoreceptors:1 ganglion cell. The remarkable total field of view, approaching 240° of visual angle and including a binocular overlap of 80° in the horizontal plane, provides an efficient predator detection capacity. The visual capabilities of the honey possum are discussed in relation to its lifestyle and the associated visual requirements.

Mammals occupying northern areas may experience reduced fitness through the deleterious effects of snow on locomotion, energy expenditure, and food acquisition. Accordingly, in areas of deep and soft snow, selection may favour mammals possessing disproportionally large feet and lower footload (body mass/foot surface area). We collected carcasses of coyote Canis latrans (n = 472), red fox Vulpes vulpes (n = 199), arctic fox Alopex lagopus (n = 52), grey fox Urocyon cinereoargenteus (n = 17), and wolf Canis lupus (n = 14) and compared body mass, total foot area, difference in surface area between front and hind feet, and footload, among species and populations. All measured morphological attributes differed significantly among canid species; grey fox had the smallest feet, whereas arctic fox had both the lightest mass and lowest footload of all canids. For all species, adult males tended to be heavier and have larger feet than did adult females, and for most species adults were heavier and larger than were juveniles. Foot area in red foxes increased significantly with latitude, with populations found north of 48 °N (i.e. approximate latitude where snow may become limiting) averaging 12% larger feet than those found farther south. For coyotes, body mass increased with latitude, with populations found north of 48 °N averaging 26% heavier mass than those occurring farther south. Coyote foot area also increased with latitude, with populations found north of 48 °N averaging 25% larger feet than those found farther south. When indices of snow severity (mean annual snowfall, mean number of days with snowcover) were considered, foot area for red foxes was correlated with annual snowfall as well as latitude, whereas coyote morphology failed to correlate with any snow-related variables. These results suggest that snow may have contributed to selection for foot size in some wild canids (i.e. arctic fox, red fox), but such selective forces were probably relatively weak and inconsistent across species.

The Madeiran land snail genus Heterostoma contains two taxa distinguished by differences in genital anatomy: one has full hermaphroditic genitalia (euphallic) while the other lacks the distal male organs (hemiphallic). Snails from the Madeiran islands of Porto Santo and Ilhéu de Cima were kept under controlled conditions differing in humidity and simulated rainfall. There were four treatments: (1) low humidity, no rainfall; (2) low humidity, rainfall; (3) high humidity, no rainfall; (4) high humidity, rainfall. For snails from Porto Santo there were viability differences between taxa under all treatments such that hemiphallics were most viable under treatment 1 and euphallics were more viable under all other treatments. There were no significant differences between taxa taken from Ilhéu de Cima. This may be a real effect or the result of smaller sample size or a combination of both. Under all conditions, both taxa from both islands show a time-dependent reduction in viability in response to rainfall. Taxa from Porto Santo also respond differently to humidity with hemiphallics surviving for less time than euphallics at high humidity. These results are interpreted as showing a difference in physiological tolerance between taxa from Porto Santo with respect to humidity. It is suggested that this ecological difference may have been a factor in the divergence of the taxa, perhaps through interaction with genital anatomy variation. No firm conclusions can yet be drawn regarding samples taken from Ilhéu de Cima.

The process of early gonadal development and the mode of sexuality were examined in the three-spot damselfish Dascyllus trimaculatus. All gonads developed an ovarian lumen and primary-growth-stage oocytes after an initially undifferentiated state. From this ovarian state or from more developed ovaries, some gonads redifferentiated into testes. None of 130 individuals examined had a gonad containing degenerating vitellogenic oocytes and proliferating spermatogenic tissue. Nineteen individuals, however, had a gonad containing degenerating cortical–alveolus stage oocytes and proliferating spermatogenic tissue. The size of these individuals overlapped with the female size range in which most females were still in the middle of the maturation process or the smallest female size class in which most females had vitellogenic oocytes. This suggests that the transition toward maleness in these individuals is likely to have occurred after oocytes in their gonads attained cortical–alveolus stage, but before their final maturation and spawning as females, and that the protogynous pattern of gonadal development in D. trimaculatus is non-functional. The observed protogynous pattern seems to have been present in the common ancestor of the genus and have been retained in this descendant species.

Non-reproductive female Damaraland mole-rats Cryptomys damarensis that were caught before a period of good rainfall (during which 90% of the average annual fell) (Group 1), exhibited a significantly lower pituitary sensitivity to gonadotrophin-releasing hormone compared to non-reproductive females (Group 2) caught in the same area, close to the end of the wet period. Group 2 were also significantly heavier than Group 1. Pituitary sensitivity was not significantly correlated to body mass within either group of females, nor within groups of reproductive males and non-reproductive males from a laboratory held colony. This suggests that rainfall may have resulted in the simultaneous, but unrelated, increase in pituitary sensitivity and body mass. Larger size and reduced sexual inhibition assist dispersal and the probability of successful independent reproduction, during periods when environmental constraints on dispersal are relaxed. These findings support the hypothesis that low rainfall may be an important constraint on dispersal and an important factor promoting the evolution of reproductive inhibition, and consequently eusociality, in this species.

In a field study on the behavioural response of grey-sided voles Clethrionomys rufocanus to predator odour ear tattoos were used for individual marking of the voles in the field. The study was conducted over three summer seasons in the tundra of northern Norway. In this paper we report our experience with ear-tattooing in order to compare it with other methods used for marking small mammals. Methods should be compared for their different influences on physiology and behaviour and to find alternatives to the widely used toe-clipping. Looking for alternatives becomes mandatory because in many countries this method needs a special permit or is totally prohibited by law. Marking a vole with ear-tattoos took us 2 min on average. The rate for the first recapture after marking voles was 87%. This is much higher than reported recapture rates for toe-clipped voles. From all recaptured individuals we were able to identify > 89.9% of the codes. The time lag between marking and first recapture was higher than the lag between second and third recapture, which indicates a trauma caused by the marking procedure. However, there was no evidence of any weight loss as reported for other marking methods, and most of the tattooed animals did not show any behaviour indicating irritation after being marked. It is concluded that ear-tattooing, as an alternative to other methods of marking small mammals is useful even in the field. However, to assess different advantages and disadvantages in other circumstances, the chosen method should be examined critically before use.

A new species of horseshoe bat, Rhinolophus sakejiensis, is described from south-central Africa, near the source of the Zambezi River in north-west Zambia. A distinct combination of noseleaf, cranial and baculum characters are diagnostic of the species. It is a member of the ferrumequinum group, and its evolutionary affinities lie closest to R. clivosus Cretzschmar, 1828 and particularly the West African R. hillorum Koopman, 1989. This discovery of a new species of Rhinolophus in the clivosus complex required reappraisal of these and other related taxa. Known only from high forest in West Africa, hillorum is the closest relative of sakejiensis collected in mesic savanna in south-central Africa. Comparisons of this new species with other large Afrotropical Rhinolophus shows that hillorum is specifically distinct from clivosus, and endorses the specific status of deckeni and silvestris. The contemporary taxonomy of Afrotropical Rhinolophus was incapable of accommodating this new taxon, and the latter part of this paper argues for a more objective characterization of rhinolophids as evolutionary species.

Successful capture of prey often depends, in part, on the magnitude, duration and speed of feeding behaviours. Animal size and experience are potentially important to these aspects of behaviour, but the effects of scale on the muscular dynamics of and capture by aquatic vertebrates remain relatively unknown. This study examines scale effects on prey capture kinematics in the nurse shark Ginglymostoma cirratum, an inertial suction feeder. Morphometric analyses were performed on the heads and feeding apparati of 12 specimens between 71 and 244 cm total length (TL). These data indicated isometric growth of the feeding apparatus. The kinematics of prey capture in another 12 specimens (33 to 268 cm TL) were recorded with high speed video (200 fps). Across the size range, maximal angular excursions remained constant whereas the maxima of linear excursions increased isometrically. However, various phases of the prey capture sequence apparently did not increase in duration. Regressions of the components of prey capture timing generally had slopes between 0 and 0.5, supporting a model of muscular scaling initially proposed for largemouth bass. This model implies that increases in the duration of prey capture are the result of physiological constraints on muscular contraction. There is also a pattern of scaling across several taxa of aquatic vertebrates consistent with a second model of musculoskeletal scaling, although it does not necessarily apply within each taxon.

Seven juvenile individuals of the Australian species Crocodylus johnstoni from the Frankfurt Zoological Park were filmed on high-speed video, at 250 fields s−1, whilst freely moving at various speeds in a long corridor. The sequences of locomotion were analysed to determine the various space and time parameters to characterize limb kinematics. We found that the animals use diverse patterns of asymmetrical gait, revealing great flexibility in limb co-ordination. In all these gaits, the forelimb strikes the ground first, in the couple made by diagonally opposite fore- and hindlimbs. Among these gaits, rotary gallop offers probably a high level of manoeuvrability, whereas transverse gallop resulted in a higher level of stability. Speed increase is achieved by half-bound and bound, the latter being the only gait used at velocities > 2 m s−1. Speed was increased mainly by increasing the stride length of the fore- and hindlimbs by simultaneously increasing both its components, the step and swing lengths. However, in bound, the step length of each forelimb increased more than the swing length, resulting in a stronger thrust action, whereas swing length increased more than step length for the hindlimb, causing the centre of mass to accelerate forwards during its ballistic phase. The asymmetrical gaits of crocodiles such as Crocodylus johnstoni are probably not functionally equivalent to the transitional asymmetrical gaits exhibited by lizards when building up into a bipedal run. These gaits are also not entirely equivalent to mammalian gaits, despite the use of vertical movements of the vertebral axis in these crocodiles, favouring an erect dynamic posture.

Agonistic and sexual interactions as well as plasma bioactive luteinizing hormone (LH) concentrations were monitored in all the adults of two colonies of the naked mole-rat Heterocephalus glaber at three phases in the pregnancy of the breeding female. Blood samples were collected at early (days 1–15), mid (days 30–40) and late (days 55–65) phases of her pregnancy, and the circulating basal plasma LH and the response to administration of 0.1 μg gonadotrophin-releasing hormone (GnRH) were examined. In both colonies it was found that non-breeding males and females showed depressed basal LH concentrations and responses to a GnRH challenge. However, there was considerable variation between individuals, in terms of both basal plasma and post-GnRH concentrations of LH, implying that certain individuals were more suppressed than others. The responses were more pronounced in non-breeding males than in non-breeding females, and this is discussed in light of the reproductive skew occurring within colonies. Few agonistic interactions occurred between the breeding female and the majority of the colony members, and overall, there was no clear relationship between plasma LH and the amount of aggression received from the breeding female. However, in one colony there was a significant positive correlation between basal plasma LH concentrations of non-breeding females and agonistic interactions received by them from the breeding female. In this same colony, older females and older and heavier males received most of the aggression from the breeding female. The second colony did not show this trend, possibly because it had recently lost many large animals during fighting for succession; in this colony sexual interactions were elevated.

The morphology of the mouthparts and proventriculus of the wood-boring isopod Sphaeroma terebrans has been described, with particular reference to its possible filter-feeding abilities. Scanning electron microscopy revealed that while the mandibles might be designed to scrape pieces of wood from the cavity wall during boring, the rest of the mouthparts are better suited for microphagous feeding. Video observations of the mouthparts demonstrated the ability of S. terebrans to filter out particulate material from the water column, by means of the filtering setae on the first three pairs of pereiopods. The morphology of the gut was found to be largely similar to that of terrestrial herbivorous isopods; primary and secondary filter apparatuses were present, but the masticatory apparatus present in terrestrial herbivores was missing. The morphology of both the gut and mouthparts provides additional support for the assumption that wood is an unlikely food source for S. terebrans.

The brush-tailed porcupine Atherurus africanus is an important source of meat for local people in tropical forested areas of Central Africa. Information on the biology of this species in free-ranging conditions is scarce. Data on its reproduction and productivity are essential to establish accurate management practices in the exploitation of this rodent. In order to provide data on the reproductive physiology and to assess the prolificacy of the brush-tailed porcupine in the wild, the structural and functional anatomy of the ovaries of free-ranging females were studied. Twenty-two female carcasses were obtained from various markets in Libreville, Gabon, between August 1995 and February 1997. Reproductive tracts were macroscopically examined for the presence of embryos or foetuses. The ovaries were embedded in paraffin wax or plastic and examined by light microscopy. The morphology and constituent cell types of the ovaries were similar to those described for other hystricognath rodents. All pregnant females had only one embryo or foetus and the number of corpora lutea (CL) per female was 19.9 ± 5.4 (mean diameter ± sd, 1709 ± 421 μm), including one CL of pregnancy (diameter, 4821 ± 1364 μm). Also, 8.9 ± 6.8 accessory CL per female in the pre-implantation and embryonic stages of pregnancy (diameter, 1629 ± 463 μm) were observed. The average active luteal volume was high (115.6 ± 73.5 mm3). The mean number of antral follicles in the adult females was 24.6 ± 9.9. The study confirms that the brush-tailed porcupine is a mono-embryonic species, as observed in captive breeding experiences, but polyovular, suggesting important ovum mortality. This unusual reproductive feature in a mammalian species gives this rodent a low reproductive productivity. Therefore, A. africanus could be more susceptible to the effects of hunting than generally thought.

The genus Gerbillus (Mammalia: Rodentia) is characterized by an important morphological homogeneity associated with an extensive karyotypic diversity. Here we describe a new species of Gerbillus from the Inner Delta of the Niger River in Mali, on the basis of morphological and chromosomal data. This new species seems to be morphologically very similar to G. campestris, another bare-footed species known from northern Africa. Nevertheless, it can be distinguished from the latter species by a different molar pattern and a specific karyotype. The three specimens on which this description is based were caught in a rocky outcrop, and behavioural observations in captivity suggest an adaptation to life in rocky habitats. This finding is unusual as rodents of the genus Gerbillus are generally sand-dwellers. Moreover, this new species enriches the gerbil community of this Sahelian region, in which at least nine species of the genus can be found. Finally, this description highlights the importance of chromosomal studies for the characterization of biological diversity in tropical rodents, where morphological sibling species are numerous.

Geographical patterns and peaks of species richness and narrow endemism (defined by range-restrictedness and range-size rarity) are described for terrestrial Afrotropical birds and subsets thereof based on residency, endemism, and taxonomy. Species richness for residents and Afrotropical endemics (species globally restricted to sub-Saharan Africa) peaks along the mountains and adjacent lowlands of eastern and southern Africa. Isolated mountains in central and western Africa and the lowlands of the north-eastern Congo Basin (Ituri) are highlighted to a lesser degree. Peaks of narrow endemism occur in these areas as well as in the Ethiopian Highlands (particularly for non-passerines), Somalia (particularly for passerines), and the Angolan Escarpment. Within residents, patterns of species richness vary greatly between Afrotropical endemics (which concentrate in forests on mountains and adjacent lowlands, and the southern Brachystegia woodlands) and non-endemic residents (which concentrate in Sudanian woodlands and the Ethiopian Highlands). Patterns of species richness of residents (species that breed in the Afrotropics) and non-breeding migrants (non-breeding visitors to the Afrotropics) also show notable differences. The latter concentrate in areas close to the Palaearctic, which forms their distributional range centres. Patterns of species richness and narrow endemism for Afrotropical endemics show broad-scale coincidence within mountains or mountain–lowland complexes, particularly the Cameroon–Bamenda Highland system, East African rift system and Eastern Arc mountains. However, fine-scale coincidence of peaks of species richness and narrow endemism within these complexes is low. Narrow endemism peaks occur in areas of topographical complexity, which may have conferred localized climatic stability over short-, medium-, and long-term climatic cycles (sensu Fjeldså, 1994; Fjeldså et al., 1997), allowing these areas to act as ‘species pumps’. Species accumulate in areas of high productivity. Lack of fine-scale coincidence of narrow endemism and species richness peaks have implications for conservation prioritization exercises.