The food resource partitioning in a community of snakes from a moist rainforest of south-eastern Nigeria (Eket, Akwa-Ibom State) is studied in the present paper. The community consisted of 24 different species, belonging to different families and ecological guilds: some species were terrestrial, some were semi-aquatic, and others were arboreal. Six species were primarily mammal-eating, two were bird-eating, four were lizard-eating, three were frog-eating, one species fed on both mammals and birds, and one species fed on both fish and frogs. A UPGMA tree diagram showed that three clusters of snakes are formed on the basis of their diet composition: a cluster formed by the two large arboreal species (Dendroaspis jamesoni and Boiga blandingi), another formed by the group of the terrestrial mammal-eating Calabaria reinhardti, Bitis gabonica, and Bitis nasicornis, and the third cluster formed by the lizard-eating Psammophis phillipsi, Thelotornis kirtlandii, and Gastropyxis smaragdina. The relationships between these and the other taxa remain unclear. In terms of both frequency of occurrence of the various prey types and biomass contribution of each prey type, the semi-aquatic snakes showed the narrowest niche breadth values and the terrestrial snakes showed the widest niche breadth values. The overlap values were not significantly correlated with the rank of phylogenetic distance. The mean overlap values calculated between species belonging to a same guild were significantly higher than those calculated between species belonging to different guilds, but the mean overlap values between species belonging to a same guild did not differ significantly among guilds. Prey size and predator size (total length) were positively correlated. There was no statistically significant difference between snake guilds as far as mean prey size is concerned, but the various species within each guild differed significantly in terms of mean prey size.

Three maned sloths were observed for a total of 680 h throughout 14 months in an Atlantic forest reserve of south-eastern Brazil. The study animals were located in the forest, monthly by radio-telemetry, and data on daily activity budgets were collected recording the actual time they spent in major activities. Individual home ranges were very small (0.5–6 ha, depending on the method used) and the sloths travelled an average of only 24 m during the 24 h period. A comparison between day- and night-range lengths suggests that maned sloths ranged more during daytime (17 m) than at night (5 m), indicating a predominantly diurnal period of activity. They rested, on average, for 74% of daytime, but a substantial variation was found between individuals (range 60–80%). Although a lack of synchrony was observed in activity pattern between study animals monitored simultaneously, all three sloths tended to start feeding and moving at the same time of the day (07:00–08:00), and the time that elapsed between the start of these activities on consecutive days was about 24 h, indicating a circadian rhythm of activity for the species. This finding contradicts previous studies on congeneric sloths, in which suggestions that Bradypus does not show cyclic patterns of activity were based on qualitative rather than quantitative data. Given the species' highly folivorous diet and the characteristic low basal rate of metabolism in this genus, the rather high levels of activity and the predominantly diurnal period of activity observed for maned sloths are probably related to the lower ambient temperatures found in the Atlantic forest when compared to other more equatorial localities of the Neotropics. Further studies with additional sloths are necessary, however, to ascertain the validity of this conclusion.

Today it is sometimes forgotten how recently ecology and animal behaviour have emerged as respectable sciences from being merely glorified nature study. I can remember hearing, only half a century ago, a distinguished professor stating firmly at a meeting of the Society for Experimental Biology, I think it was, that ‘In Cambridge we do not teach ecology!’ The transition that has taken place in attitudes since those days owes much to people like Peter Jewell. With a background in agriculture and physiology, his decision in the early 1960s to take his skills out into the field, to attempt the elucidation of some of the many problems facing real animals in the real world, was an important shift of emphasis. He brought a grasp of physiological function, and concepts of experimental rigour learned in the laboratory, to subjects that had sometimes lacked these important values. The researches which followed, often carried out in collaboration with the many colleagues and students who were attracted by his philosophy and personality, were part of the growing stream of vigorous new ideas that have shaped present-day attitudes towards ecology and ecological research.

The winter home ranges, movements and density of the jay Garrulus glandarius in the Maremma Natural Park (Tuscany, Italy) are presented, and compared with those already known for the other seasons. The movements of jays were studied for short periods over 6 years by radiotelemetric techniques (26 home ranges), direct observations of movements from vantage points, and transect counts. Summer and autumn ranges were much larger than spring and winter ones. Incremental area plots and auto-overlap analyses showed that, on average, spring ranges increased in area with time without shifting, whereas winter ranges were rather stable. In both periods, however, some birds moved as floaters since the degree of range auto-overlap decreased significantly with time. In winter and spring, range sizes of jays inhabiting different habitats were significantly different, being larger in sites with higher habitat heterogeneity. The structure of home ranges was variable in all seasons; birds showed jointed and disjointed ranges, with one or more activity centres, in all the possible combinations. In every season the average degree of range overlap between jays caught at the same site was rather high and overall actual overlap, when non-tagged birds were also considered, was even higher. No territorial behaviour was ever observed. During summer jays moved into the pinewood for the greater part of the day to collect cicadas, Cicada orni, and returned to the maquis in the evening. During autumn birds regularly moved within the maquis or from the maquis to the pinewood to cache oak (Quercus ilex) acorns. No regular long movements between habitats were observed during spring and winter. Direct observations and analyses of pellets suggested that food was abundant and highly diversified throughout the year. Thus, seasonal movements and home ranges were flexible and mainly controlled by food availability and its distribution in space and time.

This study investigated the foraging behaviour, diving behaviour, movements and diet of lactating southern sea lions in the Falkland Islands. They appeared to be primarily nocturnal, benthic foragers hunting at depths ranging from the surf line down to 250 m, and from just off their breeding sites out to 45 km offshore. Occasional longer trips may extend foraging ranges to over 150 km from breeding sites. Attendance patterns suggest that Falklands' sea lions do not haulout simply to feed their pups. Other factors such as predation and thermoregulation may cause them to come ashore. When at sea they travelled at approximately 1 m s−1, slower than previous studies of otariids indicated. Absence from the breeding site did not imply continuous foraging; all study animals used remote haulout sites away from their pups. Repeated use of the same areas and the short duration of foraging trips suggest that they were able to catch enough food within a fairly small foraging range. Data on diet support the suggestion that lactating sea lions are mainly benthic foragers. They take a wide range of prey species. The most common cephalopods were Loligo gahi, similar in size to those taken by the fishery. There is therefore potential for competition between the sea lion population and the Loligo trawl fishery. There was considerable overlap between the diet of sea lions and those of Gentoo and Magellanic penguins, which suggests that sea lions may compete with both species.

The diet of maned sloths was studied throughout 14 months in an Atlantic forest reserve of south-eastern Brazil. Three adult sloths were observed for a total of 680 h and located monthly by radio-telemetry. Data were collected on diet, recording the actual time the sloths spent eating plant species. Overall, the diet was composed of 99% leaves, with young leaves (68%) preferred to mature ones (7%) throughout the year. A higher proportion of tree leaves (83%) than liana leaves (16%) were included in the diet. When analysed together, the diet of the three animals included a total of 21 plant species (16 tree and 5 liana), but each individual made up its diet with an even smaller number of species (7–12) and with a particular subset of the local flora. This is a very small portion of the total number of tree and liana species available to the sloths; furthermore, the top species consumed were present at very low population densities in the forest. Thus, B. torquatus, like other congeneric species studied elsewhere in the Neotropics, is a strictly arboreal folivore with a highly selective diet, probably resulting from evolving physiological adaptations to cope with a smaller range of plant secondary compounds. This is possible for the species of this genus through a combination of low basal rates of metabolism, which enable the sloths to survive on an energy-poor diet, and a very long passage time of digesta, which, in turn, aids the digestion of a fibre-rich diet while possibly contributing to the degradation of secondary compounds.

The winter home ranges, movements and density of the jay Garrulus glandarius in the Maremma Natural Park (Tuscany, Italy) are presented, and compared with those already known for the other seasons. The movements of jays were studied for short periods over 6 years by radiotelemetric techniques (26 home ranges), direct observations of movements from vantage points, and transect counts. Summer and autumn ranges were much larger than spring and winter ones. Incremental area plots and auto-overlap analyses showed that, on average, spring ranges increased in area with time without shifting, whereas winter ranges were rather stable. In both periods, however, some birds moved as floaters since the degree of range auto-overlap decreased significantly with time. In winter and spring, range sizes of jays inhabiting different habitats were significantly different, being larger in sites with higher habitat heterogeneity. The structure of home ranges was variable in all seasons; birds showed jointed and disjointed ranges, with one or more activity centres, in all the possible combinations. In every season the average degree of range overlap between jays caught at the same site was rather high and overall actual overlap, when non-tagged birds were also considered, was even higher. No territorial behaviour was ever observed. During summer jays moved into the pinewood for the greater part of the day to collect cicadas, Cicada orni, and returned to the maquis in the evening. During autumn birds regularly moved within the maquis or from the maquis to the pinewood to cache oak (Quercus ilex) acorns. No regular long movements between habitats were observed during spring and winter. Direct observations and analyses of pellets suggested that food was abundant and highly diversified throughout the year. Thus, seasonal movements and home ranges were flexible and mainly controlled by food availability and its distribution in space and time.

In this study we investigated the effect of rainfall on the home range (calculated over 90 days) of adult female Arabian oryx (Oryx leucoryx) in a reintroduced population in central Oman. We looked at response to rainfall for six rain events in the period June 1986 to January 1992; rainfall was localized on five occasions and on one occasion covered the study area. Response, in terms of range and core area, showed considerable variation between rainfall events, perhaps as a result of variation in ranging behaviour between individual oryx. However, in the first 90 days after localized rainfall the home range and core area of oryx outside rain areas increased before decreasing significantly 91–180 days after rain. In comparison, range and core area of oryx inside areas of localized rainfall either did not change or decreased after rainfall as animals took advantage of improved conditions locally rather than investigating grazing elsewhere. When rain fell over the whole study area, range size did not change, but there was an immediate increase in core area and a reduction in range overlap indicating movement to new areas. During extended drought very localized rainfall caused oryx to move quickly to areas of new rain and by 28 days 70% of all adult females had found fresh grazing. Thereafter numbers declined to around 30% by 225 days, before oryx again moved back into the new rain areas. We attributed this pattern of movement to changes in the nutritional quality, measured as crude protein, of available forage. Data for single animals revealed considerable individual variation in response to rainfall; some animals moved quickly to rain whilst others failed to reach it. This variation had consequences for reproductive success and survival and illustrated that, for the oryx, response to rainfall is a key to desert success.

The activity and distribution of the lysosomal marker enzyme acid phosphatase have been studied in the epidermis during tail regeneration in the lizard Podarcis muralis. This study gives information both on the mechanism of separation of the old from the new epidermal generation and on the involvement of lysosomes in β- and α-keratinization in lepidosaurians. The biochemical analysis shows that the activity of acid phosphatase was higher in the regenerating tail than in the normal tail until the stage of skin shedding at around 25–30 days post-amputation. The enzyme was present in keratinizing layers of epidermis, and particularly in the shedding layer. The shedding layer followed the outline of the regenerating scales beneath the wound in the epidermis showing that lysosomal enzymes are involved in epidermal shedding. The ultrastructural study showed that acid phosphatase was initially localized within the lysosomes but, with the progress of differentiation, it also appeared free within the cytoplasm of the cornifying cells of the shedding complex and of the β-keratinizing cells, and in the intercellular space among them. The role of lysosomal enzymes in the shedding process and their involvement in the mechanism of β-keratinization is discussed. While the process of β-keratinization has an intracellular and extracellular localization of acid phosphatase, the process of α-keratinization shows that most acid phosphatase is localized within the cell. Lysosomes and mesos granules containing acid phosphatase were concentrated in the cytoplasm of differentiating mesos cells. Some mesos granules later discharged their contents into the extracellular space. The α-layer was partially formed in proximal regenerated scales around 30 days post-amputation. Lysosomes appeared to concentrate within pre-keratinizing cells of the α-keratin layer and little reactivity was seen extracellularly.

The objectives of the present study are to provide information about the habitat, behaviour, and reproduction of the new European frog species Rana pyrenaica, endemic in the central and western Pyrenees, and to compare the breeding characteristics of R. pyrenaica with those of four amphibians present in the same geographical area (Rana temporaria, Alytes obstetricans, Euproctus asper, and Triturus helveticus). Unlike R. temporaria, A. obstetricans, and T. helveticus, which are typically found in standing waters and are rather ubiquitous species, R. pyrenaica is a stenothermic, rheophilous species. Small torrents with cold, well-oxygenated waters constitute its typical habitat. This species – which seems much more aquatic than R. temporaria – has been most often found in sympatry with the endemic urodele E. asper. Unlike R. temporaria, the females of R. pyrenaica lay small clutches of large eggs.

Many spiders include conspicuous designs of white silk called stabilimenta in the centre of their orb webs. Stabilimenta are highly variable in their form and frequency and are hypothesized to function in either defence against predators or attraction of prey. These hypotheses generate different predictions about the effect of foraging success on variation in the form and frequency of stabilimenta. If stabilimenta serve as prey attractants, then starved spiders should invest more in them than well-fed spiders, while the opposite pattern is expected if stabilimenta function as a predator defence mechanism. This study examines the effect of variation in foraging success of the yellow garden argiope Argiope aurantia and the banded argiope Argiope trifasciata on variation of their stabilimenta and orb webs. Both species built smaller stabilimenta when fed less, even though a stabilimentum accounts for only 10% of the dry weight of an orb web. Poorly fed A. trifasciata also included stabilimenta in their webs less often than did well-fed A. trifasciata. Differences in stabilimenta were independent of differences between treatments in the orb webs themselves. These results argue against the prey attraction hypothesis, but not the predator defence hypothesis, since well-fed spiders invested more in stabilimenta.

Inter-male aggressive encounters were examined at three grey seal breeding colonies that differed in topography, adult dispersion patterns and operational sex ratios; North Rona and the Monach Isles (Scotland), and Sable Island (Nova Scotia). At North Rona, known males were observed over three successive breeding seasons, with a total of 275 males being individually identified. A single season's observations at both the Monach Isles and Sable Island provided data on 53 and 80 individual males respectively. Cardinal dominance ranks were computed for 68, 92 and 112 males on North Rona in each season respectively, 37 males on the Monach Isles and 68 males on Sable Island. All sites showed close approximation to dominance hierarchies when considering only interactions resulting in a clear outcome (wins), with less than 10% of interactions resulting in reversals. Measures of variance in male mating success showed no significant differences between colonies. These results show the existence of male dominance hierarchies in colonies from both east and west Atlantic populations and at breeding sites with widely differing habitat structure, seal dispersion patterns and levels of inter-male competition, suggesting limited plasticity in the form of grey seal mating systems and limited variation in the degree of polygyny attained at these sites.

This study investigates the effect of tooth sharpness on the force and energy necessary for a tooth to divide foods of differing physical properties. The material properties of foods are likely to affect the shape that is best to divide them. In order to test the effect of sharpness on a tooth's proficiency in dividing insect prey, experiments involving penetrating and driving through insect prey of differing physical properties were carried out using specially designed punches that varied in tip- and cusp-sharpness. A refinement of tooth measurements which are relevant to their effectiveness in penetrating and driving through food is expounded. ‘Tip-sharpness’ is defined as the radius of curvature at the tip of a cusp. ‘Cusp-sharpness’ is defined as the volume or surface area of the tooth per unit distance from the tip of a cusp. The experiments show that tooth shape is important in the force and energy needed for teeth to penetrate and drive through insects. Also, the scale of teeth is important – teeth of the same shape but different size vary in their effectiveness to divide foods.

Vestigipoda maschwitzi Disney sp. nov. is described from females and larvae collected from a colony of Aenictus gracilis in Malaysia. It is the second species in this remarkable genus, the type species being associated with a different species of Aenictus in Malaysia.

The reproductive potential of scorpions is difficult to assess since several stages of their life histories cannot be clarified under natural conditions. The female's age when she first reproduces, the frequency of parturitions, litter size, and longevity cannot be known with accuracy. A new approach to such questions is suggested, whereby clues in the female's ovariuterus can be used to shed some light on previous and forthcoming litter sizes.

The ovariuterus of a female scorpion is unique among invertebrates in that past and forthcoming parturitions can be traced in its structure. Degenerated post-partum diverticulae and the scars remaining after these have been completely resorbed indicate past parturitions, whereas young rudimentary diverticulae provide an estimate for future generations.

It is estimated that Scorpio maurus fuscus (Scorpionidae), matures in its second year, and first reproduces when 3 years old. Ovariuterus structure shows that it can have at least four and perhaps up to eight litters. If parturition takes place every year this would imply that a female scorpion can reach a minimum age of 6 years or perhaps up to 10 years. Evidence based on population analysis of females indicates that it is unlikely that all females reproduce in consecutive years; more probably they reproduce every other year. Thus, longevity may reach 9 years and perhaps as much as 17 years.

After an absence of two decades a group of bottlenose dolphins, Tursiops truncatus, became resident in the coastal waters of Cornwall, U.K. in 1991. Using a combination of field techniques and information from the general public, the movements of this group were monitored. The dolphins demonstrated a seasonal residency pattern, spending the winter in southern Cornwall and moving further north-eastward during spring and summer. Residency was flexible with a number of individual dolphins using the region intermittently. The dolphins occupied a linear range of coast of 650 km. Within this range they repeatedly made long-distance journeys. Mean swimming speed was documented at 7.9 km·h−1, with the dolphins travelling the coast at a mean of 3.6 km·h−1. The longest journey recorded covered 1076 km and took 20 days. In one confirmed case the dolphins left the south-west of England and were resighted in Wales. Such wide ranging movements have important implications for the conservation of bottlenose dolphins in U.K. waters.

The epidermal layer of the skin of the cartilaginous fish Raja clavata taken from a suitable place on the ventral side of the head was examined by light and electron microscopy. Cells of the basal layer divide and differentiate as epithelial cells of the mid-epidermis, characterized by numerous electron-dense, membrane-bound vesicles; their content is assumed to be mucus. Cells at the superficial layer of the epidermis lose these vesicles but have a palisade of mucous vesicles below the apical membrane. A modified glycocalyx coats the outer leaflet of the apical membrane.

In addition to epithelial cells, there are epidermal cells differentiated as two kinds of mucous goblet cells, sacciform cells similar to those found in teleost fish epidermis, holocrine cells with some resemblance to the club cells of teleosts but differing in their cytology, and chemosensory cells similar to those found in the oral epithelium of Raja. Merkel cells were not found. Cells that might be interpreted as ionocytes were seen but their nature was not confirmed. The epidermis is penetrated by numerous nerve fibres; swellings contain mitochondria and glycogen granules. The nerve fibres also contain 50–70 nm vesicles with an indistinct core. Cells intrusive to the epidermis include melanocytes, lymphocytes, macrophages, and several types of granular leucocyte. The cytology of the various epidermal elements is generally similar to that known in teleost fishes.

Otters are classified in the Lutrinae and are united by a suite of semi-aquatic adaptations that distinguish them from the rest of the Mustelidae. Past systematic studies have been based primarily on overall similarity of morphological characters but have not been concordant, with regard either to relationships within the subfamily or to the relationships of the Lutrinae to other taxa in the Mustelidae. We evaluate the relationships among nine of the 13 species of otters and their position in the Mustelidae through phylogenetic analysis of the complete nucleotide sequence of the mitochondrial cytochrome b gene. Based on the sequence data presented here, our results suggest that otters are divided into three primary clades that include: (1) the North American river, neotropical and marine otters; (2) the sea, Eurasian, spotted-necked, cape clawless and small-clawed otters; and (3) the giant otter. Furthermore, our results indicate that among sampled mustelid taxa, members of the genus Mustela are most closely related to otters. The hierarchical relationships among clades are not well resolved, particularly the monophyly of otters, largely because a pattern of short internal branches combined with long terminal branches suggests a rapid evolutionary radiation. Estimates of divergence time calibrated by the fossil record suggest that the lineages leading to the North American river, neotropical and marine otters, and the giant otter diverged before the end of the Miocene, much earlier than predicted from the fossil record.

This paper addresses how the wing membrane and skeletal system in bats are developmentally and functionally integrated during morphogenesis in the little brown bat (Myotis lucifugus). A truss network is used to quantify changes in the size and shape of the wing membrane during morphogenesis. Growth of the forearm and of third and fifth digits of the manus are also quantified. Principal component analysis indicates that changes in size of the wing (PC-1) contribute 78% of growth variation, whereas shape changes (PC-2, PC-3) contribute only about 18% of growth variation. ANOVA run on component scores shows significant differences in size (PC-1) of the wing between juveniles and sub-adults, whereas no significant difference in shape (PC-2 and 3) of the wing occurs during morphogenesis. In addition, growth compensation is shown to occur among sequentially developing skeletal elements comprising the hand wing. Coefficients of variation were significantly higher for phalangeal lengths than for total wing length and width. Compensation scores generated by summing residual scores produced by bivariate plots of wing bone elements show variable levels of compensation among individuals. However, a plot of scores against wing length shows compensation to occur throughout morphogenesis as scores are not correlated with wing size (r = 0.089). Apparently, selection has favoured a developmental system within which wing shape is conserved while simultaneous plasticity in the hand skeleton helps maintain functional integrity during rapid morphogenesis.

Fratia gaditana, n. gen., n. sp., is described based on the specimens obtained from the atrium of the ascidian, Clavelina dellavallei (Zirpolo), collected at Tarifa Island in Cádiz, Spain. The new species belongs to a new family of Cyclopoida. Cladistic analysis revealed that phylogenetically it is closer to the Ascidicolidae than to the two other ascidicolous families, Archinotodelphyidae and Notodelphyidae.