Ontogeny of oxygen stores and physiological diving capability in Australian sea lions

1.For air-breathing animals in aquatic environments, foraging behaviours are often constrained by physiological capability. The development of oxygen stores and the rate at which these stores are used determine juvenile diving and foraging potential.
2. We examined the ontogeny of dive physiology in the threatened Australian sea lion Neophoca cinerea. Australian sea lions exploit benthic habitats; adult females demonstrate high field metabolic rates (FMR), maximize time spent near the benthos, and regularly exceed their calculated aerobic dive limit (cADL). Given larger animals have disproportionately greater diving capabilities; we wanted to determine the extent physiological development constrained diving and foraging in young sea lions.
3. Ten different mother/pup pairs were measured at three developmental stages (6, 15 and 23 months) at Seal Bay Conservation Park, Kangaroo Island, South Australia. Hematocrit (Hct), haemoglobin (Hb) and plasma volume were analyzed to calculate blood O2 stores and myoglobin was measured to determine muscle O₂. Additionally, FMR's for nine of the juveniles were derived from doubly-labelled water measurements.
4. Australian sea lions have the slowest documented O₂ store development among diving mammals. Although weaning typically occurs by 17·6 months, 23-month juveniles had only developed 68% of adult blood O₂. Muscle O₂ was the slowest to develop and was 60% of adult values at 23 months.
5. We divided available O₂ stores (37·11 ± 1·49 mL O₂ kg−1) by at-sea FMR (15·78 ± 1·29 mL O₂ min−1 kg−1) to determine a cADL of 2·33 ± 0·24 min for juvenile Australian sea lions. Like adults, young sea lions regularly exceeded cADL's with 67·8 ± 2·8% of dives over theoretical limits and a mean dive duration to cADL ratio of 1·23 ± 0·10.
6. Both dive depth and duration appear impacted by the slow development of oxygen stores. For species that operate close to, or indeed above their estimated physiological maximum, the capacity to increase dive depth, duration or foraging effort would be limited. Due to reduced access to benthic habitat and restricted behavioural options, young benthic foragers, such as Australian sea lions, would be particularly vulnerable to resource limitation.

Impact of ripening stages of banana flour on the quality of extruded products

The study investigated the physical, nutritional and sensory properties of different ripening stages of banana during extrusion processing in combination with rice flour to develop quality snack products. Dehydrated banana flours at ripening stages 4, 5 and 6 (peel colour) were mixed separately at 40% banana to 60% rice flour levels. The mixtures were extruded through a twin-screw extruder at 120 °C barrel temperature, 220 and 260 r.p.m, screw speed and 12% feed moisture. Increase in ripeness indicated negative effect on expansion and water absorption capacity while increasing the water solubility index and moisture retention (wet basis) of the products. Protein and mineral (except for zinc and copper) content of the products were significantly different (P < 0.05) from 4 to 6 of the ripening stages. Most of the essential amino acids in the extruded products increased significantly (P < 0.05) at the ripening stage of 6. All the products were within the acceptable range in the 9-point Hedonic scale showing the best texture and flavour scores for stage 4 and 6, respectively. The extruded products show potential as snack products because of their nutritional quality and sensory acceptability.

Dispersal and recruitment of juvenile Red-capped Robins, Petroica goodenovii

Data on the dispersal and recruitment of juvenile birds following fledging are largely unreported for Australian birds. In this study, we investigated the short-distance dispersal of a sample of colour-banded, juvenile Red-capped Robins, Petroica goodenovii, in Terrick Terrick National Park, Victoria, Australia. Of 67 colour-banded juvenile birds that successfully reached independence during the 2000–01 breeding season, eight were recruited into the study area or adjacent areas for the following breeding season. A ninth bird was resighted in Gunbower State Forest, 36 km from where it was banded. This is the furthest recorded dispersal movement of a Red-capped Robin. Of 59 colour-banded juvenile birds that reached independence during the 2001–02 season, four remained within the study area for the remainder of the breeding season, but these birds were not present in the study area during the following breeding season. Juvenile birds that successfully reached independence and dispersed were heavier as nestlings, when controlled for age and date, than birds that disappeared (assumed dead) before reaching independence. Estimates of Red-capped Robin abundances within Terrick Terrick National Park were greater than those of nearby eucalypt woodlands, suggesting that the White Cypress-pine, Callitris glaucophylla, woodlands within the park offer good-quality habitat for Red-capped Robins and may be saturated with breeding territories. Thus, juveniles may be forced to establish breeding territories far from their natal territories. These results are discussed in relation to avenues for further research on juvenile dispersal in Australian birds and their conservation implications.

What`s the story? An exploration of narrative language abilities in male juvenile offenders

This paper is concerned with the narrative language (story telling) abilities of a group of juvenile offenders completing community-based court orders in Melbourne, Australia. A convenience sample of 30 male young offenders was compared with 50 male non-offenders attending government high schools in the same region of Melbourne. Participants provided an audiotaped description of a six-frame cartoon (the “Flowerpot Incident”). Samples were transcribed and subjected to story grammar analysis, to examine differences between groups regarding both structural and qualitative adequacy. Young offenders produced narratives which were significantly poorer than those of controls with respect to the presence and adequacy of the seven story grammar elements described by Stein and Glenn (In R. O. Freedle (Ed.), New Directions in Discourse Processing (pp. 53-120) 1979). Findings are discussed in relation to implications for investigative and evidentiary interviewing.

Boys` Stuff

What do guys think about growing up, friends, sex, sport, drugs and everything else that matters? In this book, teenagers write about their lives. It's honest, raw and real. They talk about what the rules are, how they break them, and what's really cool.

Banding and radio-tracking juvenile powerful owls in Melbourne, Victoria : trials and tribulations

The Powerful Owl (Ninox strenua) is Australia's largest owl. Considering their large size they are a very cryptic species, with limited sexual dimorphism, silent fight and a highly camouflaged presence amongst secluded canopy vegetation. These features enable Powerful Owl presence to often go unnoticed and even for the trained eye, extremely difficult to study. Our research has focused on monitoring the behaviour of individual Powerful Owls in urban Melbourne, Australia.
The leg banding of Powerful Owls is a somewhat contentious issue in Australia and here we report on the suitability of different types of legs bands placed on the tarsus of juvenile Powerful Owls. There has been some debate over the band size that should be used and the consequent effects bands may pose for the owls as they mature. We also investigate the usefulness of bands as a technique to identify Powerful Owls once they have dispersed from the natal territory.
Radio-tracking juvenile Powerful Owls was also undertaken during this study, primarily to determine individual behaviour from post fledging until dispersal. This is the first study in Australia to attempt radio-tracking juvenile Powerful Owls and the results from this research highlight behavioural characteristics, mortality rates post fledging and dispersal movements for the twelve months post fledging.
Overall we found that aluminium legs bands are a useful tool for individual identification of juvenile Powerful Owls post fledgling, however, their presence is somewhat difficult to determine on mature adults as the tarsus feathers tend to cover the band and make vision from the ground difficult. Aluminium leg bands are also useful as an identification tool for deceased birds. Leather leg bands are more suitable than aluminium bands when attaching radio-transmitters as these provide more flexibility and can be removed by the owl if they become irritating.
Radio-tracking juvenile Powerful Owls provided invaluable information relating to juvenile behaviour and movements, showing that juveniles actually remain in territories adjacent to their natal territory for the twelve months post fledging. This information is vital for the successful conservation of this species, particularly in relation to habitat conservation and home-range modelling.

Oral language competence, social skills and high-risk boys : what are juvenile offenders trying to tell us?

A cross-sectional study examining the oral language abilities and social skills of male juvenile offenders is described. Fifty juvenile offenders and 50 non-offending controls completed measures of language processing and production, and measures of social skill and IQ. Information about type of offending, substance use histories and learning/literacy problems was also gathered.

Young offenders performed significantly worse on all language and social skill measures, but these differences could not be accounted for on the basis of IQ. Just over half of the young offenders were identified as language impaired. This subgroup was compared with non-language impaired offending peers on a range of variables. The findings have particular implications in the areas of early intervention for high-risk boys and investigative interviewing of juvenile offenders.

Current trends in the rehabilitation of juvenile offenders

The Australian Institute of Criminology's recent work on adult male offenders has found that the most serious and persistent adult offenders had been detained as a juvenile. In terms of crime reduction, interventions that focus on reducing the likelihood of juveniles escalating to adult offenders will have significant benefits for the whole of the Australian community. Research conducted in juvenile justice settings around the world consistently shows that young people who come to the attention of criminal justice agencies have multiple problems and experience high levels of need across all areas of functioning. In meeting these needs, correctional agencies have been increasingly influenced by the model of rehabilitation known as the 'what works' approach. This paper outlines a case management framework for rehabilitating juvenile offenders that includes three of the most important 'what works' principles, namely the risk principle, the needs principle and the responsivity principle. In the longer term, the implementation of the framework will need to be evaluated to determine what works and what doesn't with rehabilitating juveniles.

The role of social networks at different stages of business formation

This study empirically tests the fundamental assumption that social networks are important to entrepreneurs. This assumption underpins most social network research conducted in the field of entrepreneurship and is seldom questioned. Empirical data were drawn from Australia’s participation in the Global Entrepreneurship Monitor project (GEM) from 2000- 2005 – an aggregate sample of 14,205 randomly selected Australians. The study demonstrated: (1) statistically significant differences in social networks when entrepreneurs and non-entrepreneurs are compared and (2) that the structural diversity of social networks changes during the entrepreneurial process. It was found that structural diversity was most important to entrepreneurs in the discovery stage, least important to entrepreneurs in the start-up stage and of medium importance to entrepreneurs in the young business stage.