A Triple-Isotope Approach to Predict the Breeding Origins of European Bats

Despite a commitment by the European Union to protect its migratory bat populations, conservation efforts are hindered by a poor understanding of bat migratory strategies and connectivity between breeding and wintering grounds. Traditional methods like mark-recapture are ineffective to study broad-scale bat migratory patterns. Stable hydrogen isotopes (δD) have been proven useful in establishing spatial migratory connectivity of animal populations. Before applying this tool, the method was calibrated using bat samples of known origin. Here we established the potential of δD as a robust geographical tracer of breeding origins of European bats by measuring δD in hair of five sedentary bat species from 45 locations throughout Europe. The δD of bat hair strongly correlated with well-established spatial isotopic patterns in mean annual precipitation in Europe, and therefore was highly correlated with latitude. We calculated a linear mixed-effects model, with species as random effect, linking δD of bat hair to precipitation δD of the areas of hair growth. This model can be used to predict breeding origins of European migrating bats. We used δ13C and δ15N to discriminate among potential origins of bats, and found that these isotopes can be used as variables to further refine origin predictions. A triple-isotope approach could thereby pinpoint populations or subpopulations that have distinct origins. Our results further corroborated stable isotope analysis as a powerful method to delineate animal migrations in Europe

Le renouvellement récent des faunes de vertébrés sur l’île de Cavallo (archipel des Lavezzi, Corse)

We present a recent survey of the vertebrate fauna of Cavallo, a small island belonging to the Lavezzi archipelago located between Corsica and Sardinia. This island is the only inhabited one off the coast of Corsica and underwent deep landscape and ecosystem changes in the past 50 years induced by touristic development. The herpetofauna of the Cavallo island has changed with two recent colonisations, one green frog and one gecko. Two amphibian species and four reptiles live nowadays on this island. Concerning the breeding landbirds, this island has been visited by ornithologists more or less regularly since 1955. Several species have colonized the island while others have left. These changes are due to important modifications of the habitats, such as urbanization, the decline of high matorral and grasslands, but also the development of gardens and the creation of a permanent wetland. Today, 13 species of landbirds breed on Cavallo. Several introduced mammal species recorded in the 1980s seem to have vanished, and today the list is restricted to the introduced Black rat and two or three bat species.Ce travail examine l’évolution des faunes de vertébrés de l’île de Cavallo au cours des cinquante dernières années. Dans l’archipel des Lavezzi, entre Corse et Sardaigne, il s’agit de la seule île para-corse à être habitée. Le développement touristique a engendré de profonds changements dans les paysages et les habitats naturels. Deux introductions d’espèces (une grenouille verte et un gecko) modifient la composition de l’herpétofaune, qui compte aujourd’hui deux espèces d’amphibiens et quatre de reptiles. Des ornithologues ont visité l’île plus ou moins régulièrement depuis 1955. Plusieurs espèces d’oiseaux nicheurs ont colonisé l’île tandis que d’autres ont disparu. Ces changements sont dus aux importantes modifications des habitats, telles que l’urbanisation, la régression du haut maquis et des pelouses et aussi le développement de jardins et la création d’une zone humide permanente. Aujourd’hui, on compte treize espèces d’oiseaux terrestres nicheurs. Plusieurs mammifères introduits notés dans les années 1980 semblent s’être éteints et la liste se limite au rat noir et à deux ou trois espèces de chiroptères.Delaugerre Michel-Jean, Thibault Jean-Claude, Beuneux Grégory. Le renouvellement récent des faunes de vertébrés sur l’île de Cavallo (archipel des Lavezzi, Corse). In: Ecologia mediterranea, tome 43 n°2, 2017. Le patrimoine naturel de l'île de Cavallo (archipel des Lavezzi, Corse) : écologie, biogéographie et conservation. pp. 207-217

Common Swifts (Apus apus) nesting in mature pine forests in Corsica

Tree breeding in holes has been recorded for the Common Swift (Apus apus) mainly in Northern Europe and Siberia. This behaviour, considered as ancestral, has also been noted in Corsican forests. Although marginal in terms of numbers, it is a perennial phenomenon. We present here a synthesis on the distribution and the characteristics of nesting sites, and we compare these breeding sites to the occurrences in continental Europe and Northern Africa. Our data add to the body of arguments in favour of the preservation of mature forests of the Corsican Pine on the island.Thibault Jean-Claude, Armand Thomas, Beuneux Grégory, Cibois Alice, Courtois Jean-Yves, Seguin Jean-François. Common Swifts (Apus apus) nesting in mature pine forests in Corsica. In: Ecologia mediterranea, tome 46 n°1, 2020. pp. 75-82

Site locations of bat hair samples.

<p>Circles are filled in according to the species or genus at that site: <i>Eptesicus serotinus</i>/<i>E. isabellinus</i>, open circles; <i>Barbastella barbastellus</i>, grey circles; <i>Plecotus auritus</i>/<i>P. austriacus</i>, black circles. Proximate sampling sites were grouped as one circle for clarity. Numbers refer to sites in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030388#pone.0030388.s003" target="_blank">Table S1</a>.</p

Results of the linear mixed-effects model fit by REML (model b) for predicting δD_h from latitude, longitude and elevation, with species as random intercept.

<p>Number of observations: 178. Number of groups (random effect species): 5. AIC = 1444.34, BIC = 1475.69, logLik −712.17. The random intercept was normally distributed (mean 0, SD 5.62), and so was its residual term (mean 0, SD 9.38). Model residuals were normally distributed (Lilliefors D = 0.0403, <i>P</i> = 0.1732).</p>2<p>: variable included as quadratic term.</p

Correlation between δD of bat hair (δD_h) and δD of mean annual (δD_p) precipitation.

<p>Regression (line), 95% confidence intervals (dashed) and regression equation are given for the whole data set (n = 178). Empty circles: <i>E. serotinus/E. isabellinus</i>; black circles: <i>Plecotus auritus/P. austriacus</i>; grey circles: <i>Barbastella barbastellus</i>.</p

Results of the linear mixed-effects model fit by reduced maximum likelihood (REML; model a1 in Table 2) for predicting δD_h from δD_p, with species as random intercept.

<p>Number of observations: 178. Number of groups (random effect species): 5. AIC = 1331.97, BIC = 1334.65, logLik −666.98. The random intercept was normally distributed, with mean 0 and standard deviation (SD) 2.54, and so was its residual term, with mean 0 and SD 9.85. Model residuals were normally distributed (Lilliefors D = 0.0266, <i>P</i> = 0.7844).</p

Multi-isotope triplet for <i>Eptesicus serotinus</i>/<i>E. isabellinus</i>.

<p>Circles represent values of <i>E. serotinus</i> samples, squares of <i>E. isabellinus</i>. Colors represent different sampling sites of hair. Yellow: 2; green: 3; pink: 6; blue: 14; red: 31 (numbers refer to sites in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030388#pone.0030388.s003" target="_blank">Table S1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030388#pone-0030388-g001" target="_blank">Figure 1</a>).</p