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Birds receiving extra carotenoids keep singing during the sickness phase induced by inflammation

Casagrande, Stefania, Pinxten, Rianne, Zaid, Erika, Eens, Marcel
Behavioral ecology and sociobiology 2015 v.69 no.6 pp. 1029-1037
Sturnus vulgaris, advertising, bacterial infections, birds, carotenoids, cell-mediated immunity, diet, immune response, inflammation, life history, lipopolysaccharides, males
Life history theory predicts that individuals have to trade-off resources between diverse energy-demanding activities, such as mounting an immune response and performing advertisement behaviour. The availability of immunomodulatory micronutrients can affect this trade-off. Carotenoids can upregulate both the humoral and cell-mediated immune response, but little is known about their effect on behavioural traits during the sickness phase induced by a common inflammation. To investigate whether dietary carotenoids can mitigate the severity of the sickness syndrome and promote fitness-related traits, we studied how the song rate of captive male European starlings (Sturnus vulgaris, Linnaeus 1758) receiving dietary carotenoids and coping with a challenge (lipopolysaccharide, LPS) mimicking a bacterial infection varied during the sickness phase and the subsequent recovery phase. We found that birds not provisioned with carotenoids and injected with LPS sang less than control birds during the sickness phase, but not during the recovery phase. Conversely, birds provided access to a carotenoid-enriched diet never decreased their song rate. Our results show that immune-challenged birds have to trade-off between mounting an immune response and advertising only when their access to dietary carotenoids is limited. No differences in song rate were observed between treatments during the recovery phase. Our study is the first to investigate the role of dietary carotenoids on a behavioural syndrome-like sickness and to show that providing a carotenoid-rich diet can alleviate the social costs associated with the occurrence of an inflammation.