The mahogany glider Petaurus gracilis is an endangered species of gliding possum that is only found within a limited distribution in North Queensland, Australia. The foraging behaviour of the mahogany glider was examined to determine how it changes seasonally, by extensive observations of radio-collared animals over a 2-year period. A total of 440 h was spent following mahogany gliders, of which 222 h of feeding behaviour was observed. Nectar and pollen were clearly the most important food items, comprising between 50 and 99% (mean 72.8%) of the observed feeding time when available. Nectar and pollen were consumed almost exclusively from Myrtaceae species with Eucalyptus, Corymbia and Melaleuca being eaten. Casual observations of a number of faecal samples showed that c. 80% of pollen grains were digested suggesting that pollen is a major source of protein. Other food items consumed included sap from Albizia procera and Acacia mangium, insects, lerps and honeydew, Acacia arils and fruit from mistletoes. In using these food items, the mahogany glider relied on complex seasonal cycles of food availability, requiring a high diversity of plants, with each species having distinct periods when it provides food during the year.

Small mammals were sampled in two natural habitats (montane stunted evergreen forests and montane grassland) and four anthropogenic habitats (tea, wattle, bluegum and pine plantation) in the Upper Nilgiris in southern India. Of the species trapped, eight were in montane evergreen forests and three were in other habitats. Habitat discrimination was studied in the rodents Rattus rattus and Mus famulus and the shrew Suncus montanus in the montane forest habitat. Multivariate tests on five variables (canopy cover, midstorey density, ground cover, tree density, canopy height) showed that R. rattus uses areas of higher tree density and lower canopy cover. Suncus montanus and M. famulus use habitat with higher tree density and ground cover and lower canopy height. Multivariate tests did not discriminate habitat use between the species. Univariate tests, however, showed that M. famulus uses areas of higher tree density than R. rattus and S. montanus. Rattus rattus was the dominant species in the montane forest, comprising 60.9% of total density, while the rodent Millardia meltada was the dominant species in the grassland. Studies of spatial interaction between these two species in habitats where they coexisted showed neither overlap nor avoidance between the species. Rattus rattus, however, did use areas of lower ground cover than did M. meltada. The analysis of spatial interactions between the species, habitat discrimination and use, and the removal experiments suggest that interspecific competition may not be a strong force in structuring these small mammal communities. There are distinct patterns in the use of different habitats by some species, but microhabitat selection and segregation is weak. Other factors such as intraspecific competition may play a more important role in these communities.

The brine shrimp Artemia, a typical inhabitant of hypersaline environments and characterized by a highly subdivided population structure, was used as a model to evaluate, under standardized laboratory conditions (at 65 ppt), primary reproductive traits (offspring quality and quantity) along with levels of reproductive isolation and degrees of divergence among populations. Intrapopulation experimental crosses and cross-fertility tests were evaluated in five populations (mostly A. franciscana) from coastal and inland environments in Chile, and in reference samples of A. franciscana (San Francisco Bay, U.S.A.) and A. persimilis (Buenos Aires, Argentina), which are the species likely to be found in Chile. The populations compared displayed significant variability in fecundity (total offspring, brood size) as well as in the ratio encystment/oviviparity. Hybrid offspring, produced abundantly in cross-fertility tests with reference populations, showed a pronounced switch to the encystment mode, particularly in crosses with A. persimilis. Exposure to a broad range of ecological conditions seems to have optimized a generalist reproductive strategy in the Artemia populations studied that combines variation in both the quantity and quality of zygotes. Laboratory cross-fertility tests evaluated prime reproductive characteristics in individual crosses with fair repeatability, as well as testing barriers to laboratory reproductive isolation. The lack of efficient mechanisms for reproductive isolation in the allopatric Artemia populations studied follows a trend often seen in other anostracods. Formerly allopatric populations have not achieved sympatry later as required by the allopatric speciation paradigm, and this is a probable explanation for production of the laboratory hybrids.

The pattern of home-range use by seven groups of tufted capuchin monkeys Cebus apella nigritus is described in the Iguazú National Park, Argentina, during 1991–94. The seasonal changes in home-range use by one of these groups between August 1997 and December 1998, are correlated with changes in food distribution and availability. Fruit availability was estimated with fruit traps, and the abundance and distribution of food was experimentally changed within the home range of one group by using feeding platforms filled with bananas. Average home-range size is 161 ± 77 ha (range = 81–293 ha, n = 7). There is a positive relationship between the number of females per group and home-range size. Neighbouring groups have partially overlapping home ranges and aggressive relationships. Fruit abundance is scarce during the winter and peaks during the spring and early summer. The pattern of home-range use by the main study group of capuchins was consistent with the hypothesis that fruit distribution and availability is the most important factor affecting the spatial use of their range. This is evidenced by the changes in range size and in range use as the distribution and abundance of their main fruit sources change seasonally. Range use shifted dramatically during the experimental phase of this study; the capuchins reduced their range and most frequently visited the areas where the feeding platforms were located. For most populations of frugivorous monkeys, fruit distribution and availability are the main factors that determine the pattern of home-range use. However, in some populations the availability of water sources and sleeping sites can have some effect on range use. For capuchin monkeys in particular, within-species variation in home-range size, degree of range overlap and interactions between neighbouring groups are large and do not serve to characterize any species of Cebus monkeys.

Prezygotic reproductive isolation has traditionally been studied from a precopulatory perspective even though postcopulatory events have been known to influence success at fertilization. Postcopulatory, prezygotic reproductive isolation (gametic isolation) has received relatively little attention mainly because the focus of research has been on the events that occur either earlier (pre-mating) or later (postzygotic) in the chain of events that lead to successful reproduction. However, recent evidence from an array of taxa from sea urchins to beetles reveals that postejaculatory, prezygotic events may be an important factor in reproductive isolation. Such a mechanism may be the driving force behind speciation in some taxa, such as free-spawning marine invertebrates, whilst it may complement pre-mating and postzygotic mechanisms in others. In this paper we draw an analogy between sperm–egg interactions and classical sexual selection theory and argue that gametic incompatibility may arise through cryptic female choice.

The importance of interactions between sharks and cetaceans has been a subject of much conjecture, but few studies have addressed these interactions. Sharks (order Selachii) have been hypothesized to be important predators on dolphins and porpoises (suborder Odontoceti). Unfortunately, there are often few data to back up claims that certain shark species are major threats to cetaceans. To help identify potential shark predators in specific locations, available data on interactions with odontocetes for all shark species that may include cetaceans in their diet are reviewed. Shark species are categorized into groups based on predatory interactions with dolphins and porpoises (regular predators, occasional predators, potential predators, ectoparasites and insufficient data). Several shark species that have been overlooked in the cetacean literature are identified as potentially important predators while others that have been suspected to be important predators are probably at most occasional predators. How shark predation can influence dolphin populations, habitat use, group size and behaviour is discussed. How risk of shark predation can vary with habitat attributes in both nearshore and pelagic waters is also discussed. Predator–prey interactions have been the focus of most studies of shark–dolphin interaction, but competitive interactions may also occur. The first analysis of shark–dolphin dietary overlap is presented, which shows it to be significant between common dolphins and several species of sharks, including species that prey upon these dolphins.

The diet of shy albatrosses Thalassarche cauta at Albatross Island, Tasmania, was examined quantitatively from 1995 to 1998. Two main sample types were examined: (1) whole stomach contents from chicks that had recently died of natural causes; (2) samples of fresh food delivered to chicks by their parents. Fresh food samples were considered most representative of the overall diet composition and, throughout the study, they were predominated by fish (89% by wet mass). Cephalopods, tunicates and crustaceans contributed 10%, < 0.1% and < 0.1% by wet mass, respectively, to the diet. There was little indication of seasonal or inter-annual variation in prey selection, as the composition of the diet was relatively constant through time. Fish from 16 species or families were identified, however, pelagic schooling Jack mackerel Trachurus declivis and redbait Emmelichthys nitidus together accounted for 57% and 80% (by number) of the fish identified in the stomach and fresh food samples, respectively. Cephalopods from 16 species or families were also identified, and here a single species (Gould's squid Nototodarus gouldi), accounted for 66% and 84% (by number) of the cephalopods identified. Both salps Pyrosoma spp. and crustaceans (largely Australian krill Nyctiphanes australis) contributed little by mass, but they occurred frequently and sometimes they accounted for a significant number of the prey items identified. Aspects of the biology and behaviour of the albatrosses and their main prey species combine to indicate that shy albatrosses have a largely predatory foraging nature. Much of their prey can be captured live, at the surface, during the day.

Evidence for signal coding for attributes such as age, sex or population of origin, was sought in odour profiles derived from natural secretions of the preorbital gland of red deer Cervus elaphus (n = 26), sika deer C. nippon (15), Chinese muntjac Muntiacus reevesi (23) and Chinese water deer Hydropotes inermis (53); from metatarsal secretions from red deer (n = 35), sika (30), fallow (193) and roe deer Capreolus capreolus (26); and from roe deer interdigital glands (n = 48). Volatiles were eluted from sample materials at body temperature, to restrict analysis to those elements which would occur within the natural odour profile; the different volatile elements were then separated by gas chromatography. Initial results of these analyses were strongly suggestive of some level of signal-coding for attributes of the signaller. Few secretions (species × gland) contained many volatiles which differed significantly between deer from different populations of origin and, except in the muntjac preorbital and sika deer metatarsal secretions, separation of populations was generally rather poor in formal discriminant function analyses (DFA). However, where no constraint is imposed on the number of volatiles allowed to enter the analysis, secretions from at least one gland accurately discriminated between the sexes in the original sample for most species; separation of sexes was only ineffective for Chinese water deer and fallow deer. Discrimination between deer of different age-classes was similarly effective in the original sample for red deer preorbital and roe deer metatarsal secretions and fair for preobital secretions of Chinese water deer; unbalanced age-structure of samples did not permit analysis for muntjac or sika deer. Sometimes the actual predictive power of discrimination was poor; it is notable that this was characteristically associated with small sample sizes and the evidence indicates that scent secretions from most species sampled here offer the potential for coding for at least the sex and age of the signaller. Although chromatographic analysis of odours from some glands reveals consistent differences between odour profiles characteristic of sex, age or population, this does not imply that the signal is deliberately coding for such information, or that the deer use the information available. It is possible that differences in the composition of secretions in relation to age or sex of the signaller, for example, is coincidental or of secondary significance.

In Zimbabwe the incidence of reported jackal rabies varies predictably over the year with peaks during June to August (cold dry season) and December to May (wet season), and may be explained by the social behaviour of jackals. June to August is the mating season, at which time home ranges increase in size, and overlap between species and neighbouring conspecifics is greater. Intra-group concordance in range use decreases in association with the social stress caused by mating and mate guarding, and young adults use peripheral areas, perhaps increasing contact with neighbouring jackals. Dispersal is most likely to occur in the mating season. These factors increase the contact rate between neighbours and, therefore, rabies incidence. In the hot dry season (the whelping season), home ranges decrease in size, and the overlap of interspecific and neighbouring conspecific ranges decreases. Concordance in range use of intra-group conspecifics increases and activity focuses on the den; inter-group contact rate therefore decreases, as does rabies incidence. The addition of juveniles to the population in the wet season increases jackal density and thus contact rate and also coincides with a high rabies incidence. Taking these factors into account, we suggest that the control of jackal rabies by oral vaccination should focus on the period before the mating season and after the whelping season.

Genetic variability in three species of Pimelodidae catfish (Iheringichthys labrosus, Pimelodus maculatus and Pimelodus cf. absconditus), collected at four sites in the Tibagi river-basin: Sertaneja, Londrina (lower Tibagi), Sapopema (middle Tibagi) and Tibagi (upper Tibagi) was analysed using RAPD and isoenzymatic techniques. Iheringichthys labrosus had the greatest genetic variability showing a proportion of mean polymorphic loci (P¯m) of 53.7%. The dendrogram showed that the individuals from the locations were clustered together, supporting the hypothesis that I. labrosus has a sedentary or localized geographical distribution. Pimelodus maculatus is the only species studied that is considered to be highly migratory. The P¯m obtained for this species was 30.2%. Their genetic dendrogram showed that the individuals were not clustered, based on the place of collection. P. cf. absconditus had a P¯m value of 47.4%, and the external morphology of this species is similar to that of I. labrosus, which hindered differentiation of individuals from the two species. RAPD and isoenzyme analysis, however, provided differential patterns for P. cf. absconditus from I. labrosus.

Due to the unknown effects of long-term sympatry and interbreeding with the domestic cat, there is an ongoing debate about the characterization and taxonomic status of the wildcat Felis silvestris in Europe. Recent results on the morphology of wild-living cats in Scotland had revealed two morphological groups, T1 and T2, defined from a discriminant function (based on intestine length and limb bone size). We compared wild-living cats of each of these types from Scotland, together with known domestic cats, using a new technique: geometric analysis of 3D landmarks, with the goal of formalizing a definition of wildcats that would assist with their conservation. Eighty-five landmarks were digitized on a set of 85 skulls and subjected to superimposition techniques and univariate and multivariate analyses. Results showed that T1 cats generally clustered together while, despite showing their own morphological characteristics, T2 cats seemed closer to domestic cats. T1 cats had the largest skulls, the lowest braincase capacity index and demonstrated the greatest sexual dimorphism. Domestic cats were more heterogeneous, exhibiting a wide overlap between males and females. Analysing individual landmarks, females showed more differences between the groups, particularly in the orbito-nasal region. Our results not only provide a completely independent verification of the T1/T2 categorization, but also show that, as a practical tool, skulls can be identified as T1 using six linear skull characters selected from the 85 landmarks. From current evidence it is not logically possible to state conclusively that T1 cats are wildcats, but our results firmly support the hypothesis that they are furthest from domestic cats. Thus, the distribution of T1 cats in Scotland provides a possible basis for wildcat conservation through protection by area.

Controlled studies with baits containing the biomarkers iophenoxic acid or tetracycline were carried out to measure bait uptake by free-living badgers. The presence of these biomarkers was determined in badger plasma and dentition. The biomarkers were then incorporated into baits to quantify bait uptake by badgers in the field. Seven captive badgers were orally dosed with iophenoxic acid, which was subsequently measured in serial plasma samples for 18 weeks. Subsequently, field studies using baits marked with iophenoxic acid were carried out at selected setts in two study areas. In other experiments, five cage-trapped badgers were orally dosed with tetracycline and released. These badgers were subsequently re-trapped and the presence of tetracycline measured in sections of canine teeth. Field trials were also carried out using baits marked with tetracycline in four separate study areas. Badgers dosed with iophenoxic acid had elevated plasma iodine in comparison to a pre-dose baseline level. The elevations in plasma iodine could be detected throughout the sampling period. Field experiments using iophenoxic acid showed that c. 80% of wild badgers had ingested the marked bait. In addition, all five badgers dosed with tetracycline had tetracycline deposits in their canine teeth. Between 20% and 77.8% of badgers trapped in the tetracycline field trials were positive for uptake of the tetracycline-marked bait. Variation in the percentage of badgers marked was attributed to several factors including seasonal timing of bait deployment. Our results indicated that iophenoxic acid and tetracycline were effective biomarkers of bait uptake by badgers.