Anti–predator training of juvenile little owls was tested in a sample of recovered owls raised in captivity in Brinzal Owl Rescue Center (Madrid, Spain). Mortality caused by predators has been described previously in released individuals. Nine little owls were conditioned during their development to a naturalized goshawk and a large live rat, whose presence was paired to the owl’s alarm call. All nine owls and seven non–trained individuals were then released during the late summer and autumn and radio–tracked for six weeks to test their survival. In total 71.4% of the trained owls survived while only the 33.3% of the untrained group were alive at the end of week six. The only cause of death that was detected was predation. Antipredator training, therefore, seems to be beneficial in maximizing survival after the release of juvenile little owls.
Urbanization is often associated with homogenization, including the homogenization of biodiversity and overpopulation by generalist species that can change community and disease dynamics. In Madrid, nestlings of Eurasian Scops Owl Otus scops frequently suffer necrotic oropharyngeal disease as a result of infection by Gongylonema sp., a parasitic nematode transmitted by adult owls to their offspring through the diet, more specifically through consumption of a pest species: the oriental cockroach Blatta orientalis. We studied how the presence of cockroaches and owl infection rates are affected by urban features such as green areas. We found that a higher number of birds were affected by the parasite in the initial period of the breeding season and in areas with greater surface area of green spaces. We suggest that urban management should promote the diversity of insects in green areas so that the owls diversify their dietary offer to their offspring, to reduce the prevalence of the disease and improve their breeding success in the city of Madrid, as this problem has not yet been described in other cities.
Physaloptera spp. are parasitic nematodes that infect the gastrointestinal tracts of many carnivores and omnivores. Although they are distributed worldwide, Physaloptera spp. have not been studied in raptors in Portugal. In this study, we report Physaloptera alata in a booted eagle (Aquila pennata) in Portugal. Adult nematodes were discovered in the gizzard of a young booted eagle, and morphological features were consistent with those of the genus Physaloptera. DNA was extracted and a PCR assay performed to amplify a region of the 18S small subunit of the ribosomal RNA gene and the cytochrome c oxidase subunit I gene. The resulting PCR products were Sanger-sequenced, and comparison with the available sequences in the GenBank database confirmed the initial morphological classification as Physaloptera sp. Phylogenetic analysis clustered the sequence within the Physaloptera group. The presence of this parasite in raptors from Portugal is of particular importance to wildlife rehabilitation centers, disease ecologists, and wildlife professionals. Furthermore, we produced a new genetic sequence and have added it to the GenBank database of parasites in birds of prey.
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