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31/07/2014
An individual-based model has been used to confront three hypotheses about the information transfer between social scavengers Gyps fulvus when searching for carrion: (1) Vultures only use personal information during foraging (‘‘nonsocial’’ hypothesis); (2) they create long chains of vultures by following both other vultures that are flying towards carcasses and vultures that are following other vultures that are flying towards carcasses (‘‘chains of vultures’’ hypothesis); and (3) vultures are only attracted by other vultures that are sinking vertically to a carcass (‘‘local enhancement’’ hypothesis). The number of vultures attending simulated carcasses were compared in a 10 000-km2 study area in northeastern Spain. The chains of vultures hypothesis overestimated the number of vultures feeding on carcasses; the local enhancement hypothesis fitted closely to the empirical data. Supported by the results, local enhancement may be the key social mechanism behind collective foraging in this and likely other avian scavengers and/or social birds. informacion[at]ebd.csic.es: Cortés-Avizanda et al (2014) Bird sky networks: How do avian scavengers use social information to find carrion? Ecology 95 (1799–1808) Doi 10.1890/13-0574.1
18/07/2014
The North American ruddy duck is an invasive alien species in Europe, which threatens the native white-headed duck through hybridisation. A substantial population established in the UK following escapes and releases beginning in the 1950s. The species then spread widely within Europe, and viable populations established in Belgium, the Netherlands, France and Spain. An international plan to eradicate the species from Europe has been adopted, but the approaches and intensity of control have varied widely between countries. The European Union is considering a new legislative instrument on Invasive Alien Species, which is likely to place responsibilities on member states to control named species. Coordinated control across those member states with remaining ruddy duck populations is likely to be an early test of any new responsibilities, with the potential to achieve the first continental scale eradication of an invasive alien species. informacion[at]ebd.csic.es: Robertson et al (2014) Towards the European eradication of the North American ruddy duck. Biol Invasions. Doi 10.1007/s10530-014-0704-3
15/07/2014
Although variation in the dorsal plumage colour of male European Pied Flycatchers Ficedula hypoleuca has received a great deal of attention, females of the species have been usually considered to be nearly uniformly monochromatic brown. Using reflectance spectrophotometry, the age-dependent variation of plumage colour in females has been explored. Disentangling the within- and between-individual effects of this pattern, a within-individual darkening of the mantle colour with age has been shown, whereas differences between individuals in structural colour expression may underlie the trend for a more reflective white in the females´ breast plumage with advancing age. The darkening of the dorsal plumage as females age reflects the most common pattern of age-related variation in males in most European populations of the species. informacion[at]ebd.csic.es: Potti et al (2014) Ontogenetic variation in the plumage colour of female European Pied Flycatchers Ficedula hypoleuca. Ibis. Doi 10.1111/ibi.12175
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    Estación Biólogica de Doñana - Consejo Superior de Investigaciones Científicas - Apdo 1056 E - 41013 Sevilla
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