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Argentine ants harm nestlings of the blue tit

The consequences of ant invasions on ecosystems may only become apparent after long periods. In addition, predicting how sensitive native fauna will respond is only possible if the underlying proximate mechanisms of their impact are identified. The attraction of the native and invasive ant community to artificial bird nests was studied, together with reproduction of a wild native songbird over five consecutive breeding seasons in relation to the presence of an invasive ant species. Biometric, reproductive and individual blood parameters of great tits Parus major breeding in invaded as compared to uninvaded sites by Argentine ants Linepithema humile were analysed. Great tits bred preferably in uninvaded territories by the Argentine ant. Moreover, Argentine ants were more abundant at nests in invaded sites, than any native ant species were at uninvaded sites. Further, Argentine ants recruited at the artificial nests more intensively and responded to a larger variety of nest (intact eggs, cracked eggs, faeces, and cracked eggs plus faeces) contents than native species. Although breeding success and adult condition did not vary in relation to invasion status, offspring quality was negatively affected by the presence of Argentine ants. Nestlings reared in invaded sites were lighter, with lower wing/tarsus length ratio and had a reduced nutritional condition and altered oxidative stress balance as measured from several blood parameters. The interspersed distribution and small distance between invaded versus uninvaded territories suggest that ant presence affects nestling condition through direct interference at the nest. These results highlight the importance of evaluating the proximate effects like physiological parameters of the native fauna, when studying invasive ant-native bird interactions. informacion[at] Álvarez et al (2020) Breeding consequences for a songbird nesting in Argentine ant' invaded land. Biol Invasions
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European Honey-buzzards use tools to attract ants for anting

European Honey-buzzards use tools to attract ants for anting

Examples of tool-use behaviours by animals outside foraging contexts are scarce and almos exclusively limited to primates. This work documents a case of tool use in the European Honey-buzzard (Pernis apivorus), a forest raptor that uses green twigs cut from maple trees (Acer monspessulanum) as a tool to attract ants. Every morning, Honey Buzzards collectec fresh maple twigs, spread them on the ground, and stretch their wings full-length. Based on postural similarities to other bird species known to grab ants and rub them into their feathers (i.e. anting behavior), it is hypothesized that through this behavior, this bird may attract ants to remove parasites. This study experimentally demonstrates that buzzards are selective in their choice of tools, as maple twigs are not only the easiest to break, but also attracted the largest number of ants compared to most plant species in the community. These results indicate that some birds can be classified as having high cognitive abilities, which allow them to perform complex behaviours. informacion[at] Camacho & Potti (2018) Non-foraging tool use in European Honey-buzzards: An experimental test. PLoS ONE 13(11): e0206843.