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A timeline for the urbanization of wild birds: The case of the lesser kestrel

The Lesser kestrel (Falco naumanni) evolved as a separate species in the Old-World kestrel radiation starting in the late Miocene. Given that the first cities were erected in the Holocene, this urban colonial raptor has only become a major town dweller recently in its evolutionary history. Today, more than 95% of lesser kestrel colonies in Spain and other Mediterranean countries are on buildings, and the remaining few are on rocky outcrops, that may have been the original nesting substrate for this cavity-nesting bird. Lesser kestrel fossils are well represented in cave sites, and their paleontological distribution, spanning from the Early Paleolithic to the Epipaleolithic, agrees well with its current breeding distribution. According to classical sources, such as the works of Columella and Pliny the Elder, and the presence of a skeletal remain in a Roman villa near Madrid, lesser kestrels may have nested in buildings and in urban settings for at least 2000e2500 years. However, there are no surviving colonies in structures older than 1400 years in Andalusia, nor in Spain. For a sample of 349 colonies on ancient buildings, a majority of the structures had been erected between the 15th and 17th centuries, this putting a time limit of about 300-600 years to the existence of those seemingly immemorial colonies. For specific towns and buildings, written references for the presence of lesser kestrel colonies do not go back more than two centuries. In fact, the Cathedral of Sevilla may be the structure with the longest continuous occupation by lesser kestrels recorded up to present time, from 1834 to 2020. Lesser kestrels were possibly too common in human settlements in the past as to be noted as special. This may explain the scarcity of references to the species until the 19th century. In any case, the same lack of information affects the other major Eurasian urban birds, as no timeline exist for the urbanization process of any other bird species. Here authors propose that lesser kestrels became urban breeders when both adequate cavities in buildings and cereal fields, where they capture their invertebrate prey, became available in their breeding range, several millennia ago. However, urban colonies, in contrast with the ones on stable geological substrates, have been forced to move from building to building when older ones became ruinous or were rebuilt, but new structures with suitable cavities became available throughout History. informacion[at] Negro et al (2020) A timeline for the urbanization of wild birds: The case of the lesser kestrel. Quaternary Sci Rev
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Scientists identify 66 alien species that pose the greatest threat to European biodiversity

Scientists identify 66 alien species that pose the greatest threat to European biodiversity

From an initial working list of 329 alien species considered to pose threats to biodiversity recently published by the EU, scientists have derived and agreed a list of eight species considered to be very high risk, 40 considered to be high risk, and 18 considered to be medium risk. The authors developed a horizon-scanning approach in order to derive a ranked list of potential invasive alien species. The approach is unique in the continental scale examined, the breadth of taxonomic groups and environments considered, and the methods and data sources used. Species considered included plants, terrestrial invertebrates, marine species, freshwater invertebrates and vertebrates. The highest proportion of the species identified originate in Asia, North America and South America. Aquatic species are most likely to arrive via shipping, while terrestrial invertebrates are most likely to arrive along with goods such as plants. The Mediterranean, Continental, Macaronesian and Atlantic biogeographic regions are predicted to be the most threatened across all taxonomic groups, while the Baltic, Black Sea and Boreal regions are least at risk. The Alpine region appears not to be under threat by any species. informacion[at] Roy et al. (2018). Developing a list of invasive alien species likely to threaten biodiversity and ecosystems in the European Union. Glob Chang Biol DOI: 10.1111/gcb.14527