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The age profile of populations fundamentally affects their conservation status. Yet, age is frequently difficult to assess in wild animals. Here, we assessed the use of DNA methylation of homologous genes to establish the age structure of a rare and elusive wild mammal: the Bechstein's bat (Myotis bechsteinii). We collected 62 wing punches from individuals whose ages were known as a result of a long-term banding study. DNA methylation was measured at seven CpG sites from three genes, which have previously shown age-associated changes in humans and laboratory mice. All CpG sites from the tested genes showed a significant relationship between DNA methylation and age, both individually and in combination (multiple linear regression R = 0.58, p < 0.001). Despite slight approximation around estimates, the approach is sufficiently precise to place animals into practically useful age cohorts. This method is of considerable practical benefit as it can reliably age individual bats. It is also much faster than traditional capture-mark-recapture techniques, with the potential to collect information on the age structure of an entire colony from a single sampling session to better inform conservation actions for Bechstein's bats. By identifying three genes where DNA methylation correlates with age across distantly related species, this study also suggests that the technique can potentially be applied across a wide range of mammals.

Road vehicle collisions are likely to be an important contributory factor in the decline of the European hedgehog (Erinaceus europaeus) in Britain. Here, a collaborative roadkill dataset collected from multiple projects across Britain was used to assess when, where and why hedgehog roadkill are more likely to occur. Seasonal trends were assessed using a Generalized Additive Model. There were few casualties in winter—the hibernation season for hedgehogs—with a gradual increase from February that reached a peak in July before declining thereafter. A sequential multi-level Habitat Suitability Modelling (HSM) framework was then used to identify areas showing a high probability of hedgehog roadkill occurrence throughout the entire British road network (∼400,000 km) based on multi-scale environmental determinants. The HSM predicted that grassland and urban habitat coverage were important in predicting the probability of roadkill at a national scale. Probabilities peaked at approximately 50% urban cover at a one km scale and increased linearly with grassland cover (improved and rough grassland). Areas predicted to experience high probabilities of hedgehog roadkill occurrence were therefore in urban and suburban environments, that is, where a mix of urban and grassland habitats occur. These areas covered 9% of the total British road network. In combination with information on the frequency with which particular locations have hedgehog road casualties, the framework can help to identify priority areas for mitigation measures.

The growth of aerosol particles, especially droplets of liquid, by condensation from the vapour phase is, unless the droplets are extremely small, largely controlled by diffusion through the surrounding medium. When, however, the radius of the drop is of the same order as the mean free path, the simple diffusion theory breaks down. Fuchs discussed this effect, by analogy with the temperature jump at the surface of a heated wire, as a discontinuity in diffusion expressible in terms of a distance A, closely related to the mean free path. The validity of this theory was demonstrated experimentally by Birks and Bradley from studies on the rate of evaporation of drops.An explicit value for A was proposed by Bradley, Evans and Whytlaw-Gray. A different value is shown to be implied by the calculations of Frossling and of Monchick and Reiss. An attempt is made, by a detailed examination of the experimental data of Bradley and co-workers, to ascertain which of these two values should be rejected.A remark of Fuchs, to the effect that A for a plane surface is two-thirds as great as A for a drop of vanishingly small radius, is considered in detail and a general formula is deduced for the variation of A with the curvature of the surface. It is shown that this dependence would be difficult to detect by experiment.The theory discussed is applicable to the growth or evaporation of very small drops, especially in the presence of surface jilms which reduce the condensation coefficient.

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