Blue Tit Research
Blue and great tits are common birds throughout Europe and are fascinating in terms of their ecology. In 2011, I joined a research project that had been studying these birds since the mid-seventies under the initiative of Jacques Blondel and Philippe Perret, from the CNRS of Montpellier.
We study populations of blue tits (Cyanistes caeruleus) in Corsica, and in the north of Montpellier, that live in two very contrasted habitats, composed mainly of the holm oak (Quercus ilex) or of the downy oak (Quercus pubescens). The former keeps its thorny, leathery leaves permanently, while the latter loses more tender leaves each fall and renews them entirely in the spring. This difference creates two types of forests, with downy oak forests offering a much greater plant biomass each spring for caterpillars, the main food used by blue tits to feed their chicks. This causes marked differences, both from a genetic and phenotypic point of view, between populations sometimes a few kilometers apart. In downy oak habitats, blue tits produce more eggs and nest earlier in the season, but survive less long than their neighbours living in holm oak habitats. Downy oak populations are also denser, with tougher competition and more abundant predators. These contrasting habitats make blue tits a great system in which to look at the Pace-Of-Life Syndrome. Since 2011, we have been measuring exploration, aggressiveness and impulsivity of hundreds of blue tits. We have shown that downy oak tits were more aggressive and superficial in their exploration than their holm oak conspecifics. These behavioural differences between populations have a genetic basis, and result in different survival probabilities. We have also started a study of the differences in the diversity and composition of the microbiota of these birds in relation to their habitat and their individual characteristics.
More recently, I also joined a project led by Anne Charmantier on the effects of urbanization on populations of great tits in the greater Montpellier region.
Collaborators : Anne Charmantier, Christophe de Franchesci, Claire Doutrelant, Arnaud Grégoire, Steven Kembel, Céline Teplitsky.
Students : Chase Carreau (MSc), Hélène Dion-Phenix (PhD), Mathias Gagnon-Barbin (MSc), Megan Thompson (PhD).
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Long term study
For more than 45 years, individual tits have been monitored throughout their lives. This research represents an exceptional wealth of information for studying the effect of environmental changes on wildlife and biodiversity.
Exploration
We have adapted the novel-environment test to the particularities of blue tits. We measure inter-individual differences in exploration that we link to variation in colouration, morphology and life-history traits in populations.
Population differences
Our blue tit populations occupy two habitats, dominated by deciduous white oak (on right above), or evergreen holm oak (on left above). The holm oak renews only the edge of its leaf crown each year, so there are fewer caterpillars for the birds.