Study of the 7Be(p,γ)8B^7Be(p,\gamma)^8B and 7Li(n,γ)8Li^7Li(n,\gamma)^8Li capture reactions using the shell model embedded in the continuum

We apply the realistic shell model which includes the coupling between many-particle (quasi-)bound states and the continuum of one-particle scattering states to the spectroscopy of mirror nuclei: $^8$B and $^8$Li, as well as to the description of low energy cross sections (the astrophysical S factors) in the capture reactions:$^7Be(p,\gamma)^8B$ and $^7Li(n,\gamma)^8Li$.Comment: 36 pages, 10 figure

Seasonal differences of corticosterone metabolite concentrations and parasite burden in northern bald ibis (Geronticus eremita): The role of affiliative interactions

The reproductive season is energetically costly as revealed by elevated glucocorticoid concentrations, constrained immune functions and an increased risk of infections. Social allies and affiliative interactions may buffer physiological stress responses and thereby alleviate associated effects. In the present study, we investigated the seasonal differences of immune reactive corticosterone metabolite concentrations, endoparasite burden (nematode eggs and coccidian oocysts) and affiliative interactions in northern bald ibis (Geronticus eremita), a critically endangered bird. In total, 43 individually marked focal animals from a freeranging colony were investigated. The analyses included a description of initiated and received affiliative interactions, pair bond status as well as seasonal patterns of hormone and endoparasite levels. During the reproductive season, droppings contained parasite eggs more often and corticosterone metabolite levels were higher as compared to the period after reproduction. The excretion rate of endoparasite products was lower in paired individuals than in unpaired ones, but paired animals exhibited higher corticosterone metabolite concentrations than unpaired individuals. Furthermore, paired individuals initiated affiliative behaviour more frequently than unpaired ones. This suggests that the reproductive season influences the excretion patterns of endoparasite products and corticosterone metabolites and that affiliative interactions between pair partners may positively affect endoparasite burden during periods of elevated glucocorticoid levels. Being embedded in a pair bond may have a positive impact on individual immune system and parasite resistance

Excretion patterns of coccidian oocysts and nematode eggs during the reproductive season in Northern Bald Ibis (Geronticus eremita)

Individual reproductive success largely depends on the ability to optimize behaviour, immune function and the physiological stress response. We have investigated correlations between behaviour, faecal steroid metabolites, immune parameters, parasite excretion patterns and reproductive output in a critically endangered avian species, the Northern Bald Ibis (Geronticus eremita). In particular, we related haematocrit, heterophil/lymphocyte ratio, excreted immune-reactive corticosterone metabolites and social behaviour with parasite excretion and two individual fitness parameters, namely, number of eggs laid and number of fledglings. We found that the frequency of excretion of parasites’ oocysts and eggs tended to increase with ambient temperature. Paired individuals excreted significantly more samples containing nematode eggs than unpaired ones. The excretion of nematode eggs was also significantly more frequent in females than in males. Individuals with a high proportion of droppings containing coccidian oocysts were more often preened by their partners than individuals with lower excretion rates. We observed that the more eggs an individual incubated and the fewer offspring fledged, the higher the rates of excreted samples containing coccidian oocysts. Our results confirm that social behaviour, physiology and parasite burden are linked in a complex and context-dependent manner. They also contribute background information supporting future conservation programmes dealing with this critically endangered species

The importance of the altricial – precocial spectrum for social complexity in mammals and birds:A review

Various types of long-term stable relationships that individuals uphold, including cooperation and competition between group members, define social complexity in vertebrates. Numerous life history, physiological and cognitive traits have been shown to affect, or to be affected by, such social relationships. As such, differences in developmental modes, i.e. the ‘altricial-precocial’ spectrum, may play an important role in understanding the interspecific variation in occurrence of social interactions, but to what extent this is the case is unclear because the role of the developmental mode has not been studied directly in across-species studies of sociality. In other words, although there are studies on the effects of developmental mode on brain size, on the effects of brain size on cognition, and on the effects of cognition on social complexity, there are no studies directly investigating the link between developmental mode and social complexity. This is surprising because developmental differences play a significant role in the evolution of, for example, brain size, which is in turn considered an essential building block with respect to social complexity. Here, we compiled an overview of studies on various aspects of the complexity of social systems in altricial and precocial mammals and birds. Although systematic studies are scarce and do not allow for a quantitative comparison, we show that several forms of social relationships and cognitive abilities occur in species along the entire developmental spectrum. Based on the existing evidence it seems that differences in developmental modes play a minor role in whether or not individuals or species are able to meet the cognitive capabilities and requirements for maintaining complex social relationships. Given the scarcity of comparative studies and potential subtle differences, however, we suggest that future studies should consider developmental differences to determine whether our finding is general or whether some of the vast variation in social complexity across species can be explained by developmental mode. This would allow a more detailed assessment of the relative importance of developmental mode in the evolution of vertebrate social systems

Effects of group size on exploration in ravens (<em>Corvus corax</em>)

Neophobia may constrain explorative behaviour, learning and innovation, while social context may facilitate approach to novel objects and acceptance of novel food. We examined the effects of neophobia on the exploration of novel objects in relation to social context in ravens (Corvus corax). Ravens are suitable subjects for studying effects of social context, as they are highly neophobic scavengers that recruit conspecifics to food. We tested two groups of six and 11 hand-raised birds in three conditions: single-bird, in dyadic combinations and sibling subgroups of three to six birds. Contrary to expectation, individuals of both groups were quicker to approach novel objects when tested alone than when tested with conspecifics. However, they spent more time close to and manipulating the novel objects in the social conditions (dyadic and group) than when being alone. We discuss the possibility that the higher latencies of dyads and groups to approach novel objects may reflect a 'negotiation' process in a 'war of attrition' between the individuals over risk-taking.</p

Novel object exploration in ravens (<em>Corvus corax</em>): effects of social relationships

Social context has been shown to encourage, or to delay object exploration and learning. This ambiguity might be due to factors such as social relationships and personality of the individuals involved. Here, we investigated in ravens (Corvus corax) individuals' consistency in response to novel objects over development and across contexts: alone versus social. In the social setting we focussed on the effects of social relationships on social facilitation during the approach to novel objects. We tested 11 hand-raised ravens with novel objects individually at three and six months of age and in dyadic combinations at six months of age. Individuals were consistent over development and contexts in their response to different novel objects. Birds joined siblings faster to approach novel objects than non-siblings. They also spent more time sitting close to siblings than to non-siblings. In male-male dyads but not in female-female dyads, subordinates approached the novel objects significantly faster than dominant birds. In contrast, dominant males were the first to approach the novel objects in mixed-sex combinations. Hence, the effect of social context seems to depend on the social relationships towards the companions and on the combination of the sexes.publishe

Patterns of excreted glucocorticoid metabolites change during development - analytical and physiological implications

In view of the consequences of glucocorticoid (GC) production, inter-individual comparisons of the hormonal response to challenges are of interest. GC excretion is widely assessed non-invasively via measurements of immunoreactive glucocorticoid metabolites (CM) in excreta by means of enzyme immunoassays (EIAs). A few methodological issues need to be considered to ensure valid results. We examined whether and how patterns (mixture) of excreted CM change during development (early and late nestling stage, adults) in blue tits and compared two EIAs. Assay 1 had been successfully validated for a number of bird species. Assay 2 used an antibody against the same antigen but raised in a different individual. The difference could affect antibody crossreactivity and therefore the suitability of assay 2 had to be validated. We compared the results of the two assays in samples of adult blue tits (handling stress experiment), chicken and quail (ACTH challenges). The CM patterns of 3–4 days old blue tit nestlings differed markedly from those of 11–12 days old nestlings and adults. Sex differences in CM patterns were found in all age classes. While assay 2 cannot be recommended for measuring stress responses in adult blue tits, it was suitable for use in chicken and quail. Our results show that a change in antibody charge may have a remarkable impact on antibody cross-reactivities with CM and may affect the biological sensitivity of an assay to measure hormonal stress responses. Furthermore, the suitability of an assay is highly species-dependent.Fil: Stöwe, M.. University of Veterinary Medicine; AustriaFil: Rettenbacher, S.. University of Veterinary Medicine; AustriaFil: Busso, Juan Manuel. University of Veterinary Medicine; Austria. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Grasse, A.. University of Veterinary Medicine; AustriaFil: Mahr, K.. University of Veterinary Medicine; AustriaFil: Vogl, W.. University of Veterinary Medicine; AustriaFil: Winkler, H.. University of Veterinary Medicine; AustriaFil: Möstl, E.. University of Veterinary Medicine; Austri