The roles of temperature, nest predators and information parasites for geographical variation in egg covering behaviour of tits (Paridae)

Aim: Nest building is widespread among animals. Nests may provide receptacles for eggs, developing offspring and the parents, and protect them from adverse environmental conditions. Nests may also indicate the quality of the territory and its owner and can be considered as an extended phenotype of its builder(s). Nests may, thus, function as a sexual and social signal. Here, we examined ecological and abiotic factors—temperature, nest predation and interspecific information utilization—shaping geographical variation in a specific nest structure—hair and feather cover of eggs— and its function as an extended phenotype before incubation in great (Parus major) and blue tits (Cyanistes caeruleus) across Europe. We also tested whether egg covering is associated with reproductive success of great tits. Location: Fourteen different study sites and 28 populations across Europe. Taxon: Parus major, Cyanistes caeruleus. Methods: We recorded clutch coverage estimates and collected egg cov...