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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]ebd.csic.es: Álvarez et al (2020) Breeding consequences for a songbird nesting in Argentine ant' invaded land. Biol Invasions https://doi.org/10.1007/s10530-020-02297-3


https://link.springer.com/article/10.1007/s10530-020-02297-3
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Feeding habits and trophic position of three marine predators in the Mediterranean Sea

Feeding habits and trophic position of three marine predators in the Mediterranean Sea

Understanding how marine predators interact is a scientific challenge. In marine ecosystems, segregation in feeding habits has been largely described as a common mechanism to allow the coexistence of several competing marine predators. However, little is known about the feeding ecology of most species of chondrichthyans, which play a pivotal role in the structure of marine food webs worldwide. In this study, the trophic ecology of 3 relatively abundant chondrichthyans coexisting in the Mediterranean Sea is examined: the blackmouth catshark Galeus melastomus, the velvet belly lanternshark Etmopterus spinax and the rabbit fish Chimaera monstrosa. To examine their trophic ecology and interspecific differences in food habits, the analysis of stomach content and stable isotopes was combined. Results highlighted a trophic segregation between C. monstrosa and the other 2 species. G. melastomus showed a diet composed mainly of cephalopods, while E. spinax preyed mainly on shrimps and C. monstrosa on crabs. Interspecific differences in the trophic niche were likely due to different feeding capabilities and body size. Each species showed different isotopic niche space and trophic level. Specifically, C. monstrosa showed a higher trophic level than E. spinax and G. melastomus. The high trophic levels of the 3 species highlighted their important role as predators in the marine food web. Results illustrate the utility of using complementary approaches that provide information about the feeding behaviour at short (stomach content) and long-term scales (stable isotopes), which could allow more efficient monitoring of marine food-web changes in the study area.informacion[at]ebd.csic.es  Albo-Puigserver et al (21015) Feeding ecology and trophic position of three sympatric demersal chondrichthyans in the northwestern Mediterranean Mar Ecol Prog Ser 524: 255–268 doi: 10.3354/meps11188