Early-life behaviour predicts first-year survival in a long-distance avian migrant

Early-life conditions have critical, long-lasting effects on the fate of individuals, yet early-life activity has rarely been linked to subsequent survival of animals in the wild. Using high-resolution GPS and body-acceleration data of 93 juvenile white storks (Ciconia ciconia), we examined the links between behaviour during both pre-fledging and post-fledging (fledging-to-migration) periods and subsequent first-year survival. Juvenile daily activity (based on overall dynamic body acceleration) showed repeatable between-individual variation, the juveniles' pre- and post-fledging activity levels were correlated and both were positively associated with subsequent survival. Daily activity increased gradually throughout the post-fledging period, and the relationship between post-fledging activity and survival was stronger in individuals who increased their daily activity level faster (an interaction effect). We suggest that high activity profiles signified individuals with increased pre-migratory experience, higher individual quality and perhaps more proactive personality, which could underlie their superior survival rates. The duration of individuals' fledging-to-migration periods had a hump-shaped relationship with survival: higher survival was associated with intermediate rather than short or long durations. Short durations reflect lower pre-migratory experience, whereas very long ones were associated with slower increases in daily activity level which possibly reflects slow behavioural development. In accordance with previous studies, heavier nestlings and those that hatched and migrated earlier had increased survival. Using extensive tracking data, our study exposed new links between early-life attributes and survival, suggesting that early activity profiles in migrating birds can explain variation in first-year survival.

The challenges of the first migration: movement and behaviour of juvenile vs. adult white storks with insights regarding juvenile mortality

Migration conveys an immense challenge, especially for juvenile birds coping with enduring and risky journeys shortly after fledging. Accordingly, juveniles exhibit considerably lower survival rates compared to adults, particularly during migration. Juvenile white storks (Ciconia ciconia), which are known to rely on adults during their first fall migration presumably for navigational purposes, also display much lower annual survival than adults. Using detailed GPS and body acceleration data, we examined the patterns and potential causes of age-related differences in fall migration properties of white storks by comparing first-year juveniles and adults. We compared juvenile and adult parameters of movement, behaviour and energy expenditure (estimated from overall dynamic body acceleration) and placed this in the context of the juveniles' lower survival rate. Juveniles used flapping flight vs. soaring flight 23% more than adults and were estimated to expend 14% more energy during flight. Juveniles did not compensate for their higher flight costs by increased refuelling or resting during migration. When juveniles and adults migrated together in the same flock, the juvenile flew mostly behind the adult and was left behind when they separated. Juveniles showed greater improvement in flight efficiency throughout migration compared to adults which appears crucial because juveniles exhibiting higher flight costs suffered increased mortality. Our findings demonstrate the conflict between the juveniles' inferior flight skills and their urge to keep up with mixed adult-juvenile flocks. We suggest that increased flight costs are an important proximate cause of juvenile mortality in white storks and likely in other soaring migrants and that natural selection is operating on juvenile variation in flight efficiency.

Integrating movement ecology with biodiversity research - exploring new avenues to address spatiotemporal biodiversity dynamics

Movement of organisms is one of the key mechanisms shaping biodiversity, e.g. the distribution of genes, individuals and species in space and time. Recent technological and conceptual advances have improved our ability to assess the causes and consequences of individual movement, and led to the emergence of the new field of 'movement ecology'. Here, we outline how movement ecology can contribute to the broad field of biodiversity research, i.e. the study of processes and patterns of life among and across different scales, from genes to ecosystems, and we propose a conceptual framework linking these hitherto largely separated fields of research. Our framework builds on the concept of movement ecology for individuals, and demonstrates its importance for linking individual organismal movement with biodiversity. First, organismal movements can provide 'mobile links' between habitats or ecosystems, thereby connecting resources, genes, and processes among otherwise separate locations. Understanding these mobile links and their impact on biodiversity will be facilitated by movement ecology, because mobile links can be created by different modes of movement (i.e., foraging, dispersal, migration) that relate to different spatiotemporal scales and have differential effects on biodiversity. Second, organismal movements can also mediate coexistence in communities, through 'equalizing' and 'stabilizing' mechanisms. This novel integrated framework provides a conceptual starting point for a better understanding of biodiversity dynamics in light of individual movement and space-use behavior across spatiotemporal scales. By illustrating this framework with examples, we argue that the integration of movement ecology and biodiversity research will also enhance our ability to conserve diversity at the genetic, species, and ecosystem levels.

Virological monitoring of white storks (Ciconia ciconia) for avian influenza

Between 2003 and 2008, more than 600 white stork (Ciconia ciconia) nestlings in the German federal state of Brandenburg were ringed and examined for influenza A viruses. With the spread of highly pathogenic avian influenza virus (HPAIV) of subtype H5N1 among wild birds in Germany in spring 2006, dead wild birds, including 88 white storks, were tested for infection with HPAIV. Furthermore, fresh fecal samples were examined by RT-PCR to monitor the occurrence of HPAIV in adult storks. While the monitoring of nestlings and adult white storks failed to yield evidence of influenza A virus infections in these birds, two storks found dead in April 2006 in the same location tested positive for HPAIV H5N1. Sequence analysis revealed that the virus isolated from one of the storks belonged to clade 2.2, which was commonly found in wild birds in the north of Germany and other European countries during the epidemic in 2006. Despite these two cases, white storks seemed to serve as neither a vector nor as a reservoir for HPAIV in Germany. The risk of white storks transmitting HPAIV to domestic poultry and humans is low.

Riboflavin synthases of Bacillus subtilis. Purification and properties

A variety of Bacillus and Clostridium strains were found to contain two forms of riboflavin synthase which can be easily separated by density gradient centrifugation. The fast sedimenting species accounts for 12 to 44% of the total riboflavin synthase activity in the strains analyzed. Both riboflavin synthases were purified to apparent homogeneity from cell extracts of a genetically derepressed mutant of Bacillus subtilis. The specific activities of the pure proteins were 50,000 nmol mg-1 h-1 (light enzyme) and 2,000 nmol mg-1 h-1 (heavy enzyme). The sedimentation velocities (S20,w) were 4.1 and 26.5 S, respectively. Light riboflavin synthase showed a molecular weight of 70,000 in sedimentation equilibrium experiments. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed a single band corresponding to a molecular weight of about 23,500. Thus the enzyme appears to consist of three identical subunits (alpha type). Heavy riboflavin synthase has a molecular weight of 1,000,000 as shown by sedimentation equilibrium analysis. The protein appears to consist of 2 or 3 alpha subunits and approximately 60 beta subunits. A fragment apparently identical with light riboflavin synthase can be obtained from the heavy enzyme by mild dissociating treatment.