“…Their inclusion is noteworthy because they constitute only a small fraction of the plants available as nesting materials within the wider environment, and yet they are highly sought after because they contain a high abundance of volatile secondary metabolites that reduce the abundance of a range of nest-dwelling parasites (Belandrin et al, 1985;Dubiec et al, 2013). Accordingly, there is evidence that birds mitigate the effects of parasites by choosing nest sites containing few parasites (Mappes et al, 1994;Rendell and Verbeek, 1996;Mazgajski, 2007;Suárez-Rodríguez et al, 2013) and by incorporating aromatic plant materials into their nests to reduce either the abundance or virulence of parasites (Wimberger, 1984;Clark and Mason, 1985, 1988Clark, 1991;Shutler and Campbell, 2007). Both blue tits and great tits incorporate aromatic plants into their nests (Cowie and Hinsley, 1988;Bańbura et al, 1995) and detailed studies of Corsican blue tits have shown that nest-building females incorporate between one and five aromatic herb species into their nests (Lambrechts and dos Santos, 2000;Lafuma et al, 2001;Petit et al, 2002;Lambrechts et al, 2008;Mennerat et al, 2008).…”