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Optimal annual routines of non-migratory birds: the effects of state

Final Activity Report Summary - ANNUAL ROUTINES (Optimal annual routines of non-migratory birds: the effects of state)

The bird organisms’ internal state, e.g. health, immune function, energetic reserves and feather quality, can significantly influence their behavioural decisions and life history strategies. In order to achieve a better understanding of the evolution and ecology of life history and behaviour it is important to put great emphasis on the study of internal state and its interaction with behaviour and life history.

In this study we empirically investigated the factors affecting feather quality and health status in birds and theoretically examined the effects of energetic reserves on immune defence and the effects of food availability on population processes in migratory birds. We showed that during ontogenic development the young birds adaptively allocated feather deformities to feathers that would be soon replaced in the subsequent moult. We also pointed out that moult might be more demanding for birds in terms of health status than it was previously thought. By developing simple models of immune response we found that animals with higher reserves should invest more in their immune system and that, owing a two line defence, i.e. constitutive immunity and immune response, was much more efficient, both in terms of energy and survival expectation. We found a surprisingly large effect of food deprivation during the migratory journey on the population dynamics of migratory birds. Furthermore, our state-dependent optimal annual routine model showed that internal state variables, like energetic reserves, might be efficiently used to predict population processes.