Populations of feral (not owned by humans) and domestic cats Felis catus coexist in most inhabited islands, and they have similar impacts on native species. Feral cats are generally believed to vary their diet according to prey availability; however, no previous studies of diet have tested this hypothesis on insular ecosystems with a limited range of available prey. Because domestic cats kill prey independently of hunger, the spatial extent of their impact on wildlife will be influenced by home‐range size. In this study, we combined dietary information with cat movements to assess the impacts of feral and domestic cats on island biodiversity. We quantified the diet of cats from scat samples collected across one year and tested whether diet varies by season. The abundance of main prey categories was also estimated to document seasonal variation in prey availability for cats. Finally, we tracked domestic cats by global positioning system units in all four seasons to examine whether home‐range patterns varied seasonally. The diet of cats constituted three prey groups (rodents, birds and invertebrates), and the seasonal variation in consumption of each taxon matched the seasonal variation in prey availability, thus supporting the generalist behaviour of cats on oceanic islands. Roaming behaviour varied among individuals and across seasons, but could not be explained by availability of prey. Unconfined cats had larger home‐ranges than confined cats, but most domestic cats strayed <1 km from home. Thus, confinement of domestic cats might reduce the spatial extent of cat impact on native prey populations on oceanic islands.

Urbanization, one of the most extreme human-induced environmental changes, represents a major challenge for many organisms. Anthropogenic habitats can have opposing effects on different fitness components, for example, by decreasing starvation risk but also health status. Assessment of the net fitness effect of anthropogenic habitats is therefore difficult. Telomere length is associated with phenotypic quality and mortality rate in many species, and the rate of telomere shortening is considered an integrative measure of the ‘life stress’ experienced by an individual. This makes telomere length a promising candidate for examining the effects of urbanization on the health status of individuals. We investigated whether telomere length differed between urban and forest-dwelling common blackbirds ( Turdus merula ). Using the terminal restriction fragment assay, we analysed telomere length in yearlings and older adults from five population dyads (urban versus forest) across Europe. In both age classes, urban blackbirds had significantly shorter telomeres (547 bp) than blackbirds in natural habitats, indicating lower health status in urban blackbirds. We propose several potential hypotheses to explain our results. Our findings show that even successful city dwellers such as blackbirds pay a price for living in these anthropogenic habitats.

Leucism is the total or partial lack of melanins in the skin and associate structures (i.e. hair or feathers). Little is known about the factors influencing this chromatic aberration although some local studies suggest that there is an effect of habitat, age and sex. To test these hypotheses and expand our knowledge on leucism, we carried out a large‐scale study using common blackbirds Turdus merula as our model species. Given the poor information available on this topic and the variability of methodological approaches, we used three different methods to assess the effect of these variables in the presence of leucism: transects, bird captures and citizen science information (pictures from internet). We found an effect of habitat indicating that there are more leucistic blackbirds in cities than in non‐urban areas. In addition, we found a positive association between presence of white feathers and age providing the first large‐scale support for the progressive graying hypothesis in birds. This chromatic aberration was also influenced by sex, with males showing higher probability of leucism than females, although only for the capture data, indicating that the method used to study this phenomenon can partly influence our conclusions, and therefore suggesting caution when planning future studies in this topic.

Alien mosquito and vertebrate host species may create novel epidemiological scenarios for the transmission of pathogens naturally circulating in the invaded area. The exotic Monk parakeet (Myiopsitta monachus) has established populations in Europe and is currently considered an invasive pest. Due to their high abundance in urban areas, Monk parakeets could be involved in the transmission of pathogens, potentially affecting wildlife and livestock. To test this hypothesis, we determined the prevalence and diversity of three vector-borne parasites, namely Plasmodium, Haemoproteus and Leucocytozoon, in Monk parakeets from Barcelona. Many areas of southern Europe shelter high densities of the invasive Asian tiger mosquito Aedes albopictus, which in addition to native mosquito species could affect the transmission of mosquito-borne parasites, such as avian Plasmodium. Thus, we also sampled mosquitoes in the area to trace their blood-feeding hosts and determine the presence of Plasmodium parasites. Monk parakeets were neither infected by Plasmodium nor by Haemoproteus parasites, and only five individuals (3.13%; n = 160) were infected by Leucocytozoon. Monk parakeets were bitten by Culiseta longiareolata and represented 9.5% of Culex pipiens blood meals. The invasive Ae. albopictus showed a clear anthropophilic feeding pattern, with humans dominating its diet. Three Plasmodium lineages were detected in pools of Cx pipiens. These results suggest that Plasmodium circulating in the area cannot develop in the invasive Monk parakeet, in spite of the relatively high fraction of native mosquito vectors feeding on this species in its invaded distribution range.

Aedes vittatus is currently found in Africa, Asia and Europe, where it acts as a vector of pathogens causing animal and human diseases (e.g. chikungunya, Zika and dengue). Like other Aedes species, Ae. vittatus is able to breed in artificial containers. The ECDC has recently highlighted the need for molecular tools (i.e. barcoding characterization) that enable Aedes species to be identified in entomological surveys. We sampled mosquito larvae and adults in southern Spain and used a molecular approach to amplify and sequence a fragment of the cytochrome c oxidase subunit 1 gene (barcoding region) of the mosquitoes. The blast comparison of the mosquito sequences isolated from Spain with those deposited in public databases provided a ≥ 99% similarity with sequences for two Aedes mosquitoes, Ae. vittatus and Ae. cogilli, while similarities with other Aedes species were ≤ 94%. Aedes cogilli is only present in India and there are no records of this species from Europe. Due to the low genetic differences between Ae. vittatus and Ae. cogilli, the barcoding region should not be used as the only method for identifying Ae. vittatus, especially in areas where both of these Aedes species are present. This type of analysis should thus be combined with morphological identification using available keys and/or the characterization of other molecular markers. In addition, further entomological surveys should be conducted in order to identify the fine-scale distribution of this mosquito species in Europe.