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.

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 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.

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.

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.

We studied the use of European hare (Lepus europaeus) carcasses by avian scavengers in Argentinean Patagonia. A total of 16 hare carcasses were placed in locations that could be observed without disturbing birds feeding on them. Six avian species fed on these carcasses: chimango caracara (Milvago chimango), crested caracara (Polyborus plancus), black vulture (Coragyps atratus), grey eagle-buzzard (Geranoaetus melanoleucus), red-backed hawk (Buteo polyosoma) and cinereous harrier (Circus cinereus). Turkey vultures (Cathartes aura), although abundant, never fed on the hare carcasses. The Andean condor also did not feed on the carcasses. Mammals visited hare carcasses on only two occasions. Of the hare carcasses, 69% were fully consumed during the first day of exposure and 25% in two days. There was no difference in the time elapsed from the placement of the carcass and its detection by crested and chimango caracaras. There were similar time periods from detection to first arrival, and time elapsed from first arrival to the start of feeding at the carcass by crested and chimango caracaras. Hare body parts were consumed in different proportions by crested and chimango caracaras whereas black vultures consumed the whole carcass. Interspecific hierarchies at the carcass in a decreasing sequence of dominance were crested caracara > black vulture > chimango caracara, coinciding with that expected from a body mass perspective. The scavenging species that consume hare carcasses did not show a clear pattern denoting they were a highly interdependent assemblage in the way described for scavengers in Africa.

The influence of ambient temperature on daily activity level was assessed for greater kudus observed in two study areas in South Africa. Active time proportion for adult females and subadults of both sexes was significantly negatively correlated with maximum daily temperature, but uninfluenced directly by cloud cover. However, maximum temperature differences between days accounted for only a quarter of the variability in active time. On most days the overall activity level and hence daily foraging time allocation were somewhat lower than the maximum levels observed for the prevailing temperature conditions. The upper limit to the distribution of active time was lower during the mild dry season than over the hot wet season, probably due to a seasonal change in pelage by kudus. Temperature influences were strongest during the early growing season, when food availability was low and conditions frequently hot. The active and foraging times of kudus during daylight hours appeared to be restricted below the target level only when maximum daily temperature exceeded 36 °C in the wet season, and 30 °C in the dry season. Only 15% of days exceeded these levels during the respective mid-seasonal periods, suggesting that foraging activity was effectively constrained by thermal tolerance on only about one day in seven. Optimal foraging models that assume thermal stress to be a consistent daily constraint on foraging time may be misleading.

The highveld mole-rat Cryptomys hottentotus pretoriae occurs in the summer rainfall region of the highveld of South Africa. It lives in colonies of up to 10 individuals, in which reproduction is limited to one to two of the largest males and the largest female in the colony. Of three field captured colonies, the mean colony size was 10 ± 0 animals with a mean biomass of 900 ± 147 g. The study colony had a sex ratio of 1.5:1 in favour of males.

The social hierarchy of the highveld mole-rat is non-linear and has a value of 0.3 calculated from Landau's linearity index. Dominance was negatively correlated with capture order.

Histological examination of the gonads of reproductively active and sexually quiescent members of both sexes of two colonies provides further support of there being a single reproductive male and female responsible for procreation in the colony.

The non-reproductives of both sexes appear to be important in burrow maintenance activity and in foraging for geophytes upon which the mole-rats feed. The non-reproductive members of the colony cannot be subdivided into different worker groups based on body mass. The available evidence suggests that the highveld mole-rat is a transiently social species, at one extreme of a sociality continuum in the genus Cryptomys. The position of this subspecies in respect to the sociality continuum is discussed.

Life-history models suggest that ‘costs of reproduction’ can influence the evolution of sexual dimorphism, but empirical data on this effect are scarce. We tested the idea using ‘flying lizards’ (Asian agamids of the genus Draco), because the evolution of ‘flight’ (gliding) is likely to have increased the degree to which pregnancy affects maternal locomotor ability (and hence, we infer, has increased the ‘costs of reproduction’). As predicted, Draco display patterns of sexual dimorphism that are different from those seen in most other lizards. The ‘wings’ (gliding membranes) of female D. melanopogon are significantly larger than those of males of the same body size, a dimorphism that we attribute to natural selection on the ability to glide while encumbered with eggs. Comparisons with non-flying lizards suggest that the same selective pressure has also reversed pre-existing patterns of sexual dimorphism in body size and body proportions (relative head size, relative tail length). Measurements of wing-loading, centre of balance and gliding distances of preserved specimens support the hypothesis that a larger body, relatively larger head, and longer tail may improve a female's aerial mobility when she is gravid. Thus, selection for locomotor ability in egg-burdened females (reduction in ‘costs of reproduction’) may have been responsible for a reversal of sexually-selected traits in this lineage.

Phylogenetic relationships of 31 pomacanthid species representing all genera were investigated by horizontal starch gel electrophoresis. Nei's genetic distances (D) were calculated and dendrograms constructed from allozyme variation in 23 loci. The average D value was 0.03 between conspecific colour variants, 0.40 between congeneric subgenera, and 1.27 between confamilial genera. From the dendrograms the following were revealed: (1) the generic status of Apolemichthys arcuatus and Holacanthus venustus, as well as the generic and subgeneric status of Centropyge multifasciata were confirmed; (2) the subgeneric status of Xiphypops was confirmed; (3) Pygoplites diacanthus was found to be closely related to members of the subgenus Pomacanthus; (4) Pomacanthus zonipectus was found to be biochemically distinct from its con-subgeners; (5) the genera Pomacanthus and Holacanthus are more closely related than currently thought; (6) the Genicanthus species might warrant a subfamily of their own.

The first successful captive maintenance of living terrestrial Geonemertes nemertines is reported. Behavioural observations are described, including the first data on diet in this genus. The species G. pelaensis is found to be a predator of small molluscs. In 1907 the Seychelles population was described as a distinct species, G. arboricola, largely on the basis of its arboreal habit. Recent field data from the Seychelles islands of Mahé and Silhouette confirm the tendency towards arboreal behaviour.

The European colonists of Tasmania named the thylacine Thylacinus cynocephalus a ‘marsupial wolf’ or the ‘Tasmanian tiger’ or ‘hyena’, in reference to its resemblance to large canids and the bold stripes on its rump. The largest marsupial carnivore in historic times, it was persecuted for alleged sheep killing and became extinct before its ecology was documented. We have reconstructed the likely prey size and the hunting and killing methods of the thylacine by comparing canine tooth strength and limb bone length ratios with those of extant marsupial and placental carnivores. The thylacine was probably a pounce–pursuit predator of fairly open habitats, which killed medium-sized prey (1–5 kg) that were small relative to its body size (15–30 kg), with a crushing, penetrating bite. The trophic niche of the thylacine was similar to that of smaller canids such as the coyote Canis latrans (rather than the wolf C. lupus), but ecomorphological convergence of the thylacine with canids was superficial. Phylogenetic constraint has resulted in unique patterns of tooth eruption, molar tooth and jaw geometry, calcaneum architecture, and perhaps FMT/running speed relationships in the Dasyuroidea.

Are British animals and plants being threatened by the invasion of alien species? This was the question addressed at a Scientific Meeting of the Zoological Society of London on 10 March 1998 in three talks exploring the potential impacts of invading Chinese mitten crabs in the Thames catchment (Paul Clark and Philip Rainbow, The Natural History Museum), introduced foreign crayfish (David Holdich, University of Nottingham) and alien terrestrial flatworms (Hugh Jones, University of Manchester).