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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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Environmental and anthropogenic drivers of brown bear damage

Environmental and anthropogenic drivers of brown bear damage

In Europe every year about 12,000 sheep and goats and 2,000 beehives are claimed lost due to brown bear damage and compensated to farmers. Just a few countries account for the majority of these losses. This study highlights that these differences are related to management and land-use practices, and not to bear abundance. A wolf preying on sheep or a bear raiding an apiary often imply economic and emotional losses to farmers and often lead to negative attitudes towards the wildlife causing the damage. This has triggered that in the past humans did everything to exterminate these species, which then were extirpated in many countries and regions. Nowadays things have changed: wolves, bears and other predator species are protected by law and cannot be legally persecuted any longer. To support protection, many countries provide economic compensation to offset these losses through environmental agencies or other organizations. This study shows that the number of compensations for bear damage greatly differ among European regions. For instance, in Norway approximately 900 claims are compensated every year, while in Estonia only 30. These differences are larger if we take into account that in Estonia there are 4 times more bears than in Norway, or, in other words, that the number of compensations per bear is 150 times higher in Norway than in Estonia. Why those differences? The study reveals that we have to look into what humans do. How the claims are compensated, which management practices, like supplementary feeding of bears, are used or the amount of agricultural land in the area, all influence the final number of claims. However, the abundance of bears has no influence. A practice commonly used is to reduce the number of bears by establishing culling quotas. This study finds that things are not so simple and that the regions where bears are hunted or that have less number of bears are not necessarily the ones with less claims. The way of compensating damage differs across countries and this is reflected in the number of compensations. An example of good practice is Sweden. There, the government subsidizes preventive measures, such as dogs and electric fences, to protect livestock and apiaries. If damage is claimed by a farmer, then a damage inspector has to verify that it was caused by a bear and compensations are only paid if preventive measures were used. On the other extreme, in Norway up to 95% of compensation payments for livestock losses are not verified to be made by bears and correspond to free ranging and unprotected sheep. It is interesting that these differences between neighbouring countries are not rare across Europe. The same bears are blamed for numerous damages on one side of the border, and for just a few on the other. informacion[at]ebd.csic.es: Bautista et al (2016) Patterns and correlates of claims for brown bear damage on a continental scale. J Appl Ecol doi:10.1111/1365-2664.12708


http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12708/full