Multiple isotope tracers in fur keratin discriminate between mothers and offspring.

RATIONALE: Isoscape origin models for mammals may be impaired by fractionation and routing of isotopes during lactation. Here, we tested if the stable carbon, nitrogen and hydrogen ratios of juvenile bats differ from those of their mothers and if derived isotopic dietary niches and geographical assignments vary accordingly between mothers and juveniles. METHODS: During the post-lactation period, we collected fur of juvenile and female common noctule bats (Nyctalus noctula) from the same maternity roost. Using a combination of elemental analysis and stable isotope ratio mass spectrometry, we measured the hydrogen, carbon and nitrogen isotope ratios in fur keratin. The hydrogen isotope ratios were measured for the non-exchangeable portion of hydrogen in keratin. The derived isotopic niches and isoscape origin models were compared between mothers and juveniles. RESULTS: The fur keratin of juveniles was enriched by 1.6‰ in 15 N and depleted by 2.9‰ in 13 C compared with that of the mothers. In addition, the hydrogen isotope ratios were 13.4‰ lower in the fur keratin of juveniles than in that of mothers. The estimated isotopic niches of nursing females and juveniles were not overlapping and differed in size. Overall, the isoscape origin models projected juveniles as being from a more northern origin than the mothers; yet both models suggested the study site as a likely place of origin. CONCLUSIONS: Our results suggest that isotope ratio data of juvenile bats should not be used for transfer functions in isoscape origin models because of isotopic routing and discrimination during lactation. Not accounting for age effects may increase the inaccuracy of geographical assignments in mammals when based on stable hydrogen isotopes.

Variability and repeatability of noctule bat migration in Central Europe: evidence for partial and differential migration.

Each year, large numbers of bats move across Europe between their summer and winter areas, yet even though many of them are endangered and legally protected, we are unaware about many aspects of their migratory behaviour. Here, taking Nyctalus noctula as a model species, we used stable hydrogen isotopic values in fur ( δ2Hf) as an endogenous marker to shed light on the migratory behaviour of more than 1000 bats from hibernacula across Central Europe. Specifically, we asked the following questions: how flexible is migration in temperate zone bats? Which general migration pattern do noctule bats follow? How repeatable and thus predictable is the migratory behaviour of individuals? Do morphological correlates of migration occur in bats? Our study confirmed that noctule bats engage in partial and female-biased migration across Europe, suggesting the strongest migration pressures for northern populations. Further, we revealed a combination of partial and differential migration patterns with highly variable migration distances which lead to a pronounced mixing of different source populations in hibernacula where mating occurs. Most individuals were consistent in their migration strategy over time, i.e. 86% could be repeatedly assigned to either long-distance or regional origin across years. This is consistent with our finding that the between-individual component explained 84% of the variation in δ2Hf values, suggesting specialized individual migratory behaviours and a strong natal philopatry. We discovered a positive correlation between forearm length and migration distance and support for sex-specific effects of migration on body condition. Our study elucidated migration patterns over large geographical scales, demonstrating that considerable numbers of migratory bats originating from distant populations depend on hibernacula across Central Europe, calling for international conservation management.

Diverse replication-associated protein encoding circular DNA viruses in guano samples of Central-Eastern European bats.

Circular replication-associated protein encoding single-stranded DNA (CRESS DNA) viruses are increasingly recognized worldwide in a variety of samples. Representative members include well-described veterinary pathogens with worldwide distribution, such as porcine circoviruses or beak and feather disease virus. In addition, numerous novel viruses belonging to the family Circoviridae with unverified pathogenic roles have been discovered in different human samples. Viruses of the family Genomoviridae have also been described as being highly abundant in different faecal and environmental samples, with case reports showing them to be suspected pathogens in human infections. In order to investigate the genetic diversity of these viruses in European bat populations, we tested guano samples from Georgia, Hungary, Romania, Serbia and Ukraine. This resulted in the detection of six novel members of the family Circoviridae and two novel members of the family Genomoviridae. Interestingly, a gemini-like virus, namely niminivirus, which was originally found in raw sewage samples in Nigeria, was also detected in our samples. We analyzed the nucleotide composition of members of the family Circoviridae to determine the possible host origins of these viruses. This study provides the first dataset on CRESS DNA viruses of European bats, and members of several novel viral species were discovered.

Mating without intromission in a bat.

Copulatory behaviours stand as cornerstones of sexual selection, yet they remain mysterious in many species. Because of their nocturnal and elusive lifestyle, the copulatory behaviours of bats have been mostly overlooked1. Several aspects of bat reproduction differ from other mammals (e.g. prolonged sperm storage2, delayed development3). Here, we show that in serotine bats (Eptesicus serotinus) the penis is used as a 'copulatory arm' rather than an intromittent organ, revealing a novel copulatory behaviour in mammals.