Why do female Blue Tits (Parus careuleus) bring fresh plants to their nests?

Effect of Old Nest Material on Nest Site Selection and Breeding Parameters in Secondary Hole Nesters — a Review

“…It is possible that bringing "green" material to the nest, observed in many species, occurs to control ectoparasites and other pathogens (e.g. Clark 1991, Bańbura et al 1995, Lafuma et al 2001, Gwinner & Berger 2005. It should also be remembered that the negative effect of ectoparasites may be compensated by adult birds, for example, by increasing parental expenditures (e.g.…”

Horizontal Transmission and Reproductive Rates of Hen Fleas in Great Tit Nests

“…Starling nests provisioned with such green material had lower mite loads at the end of the breeding attempts than nests where this material had been removed (Clark & Mason 1985. Although blue tits, Parus caeruleus (L.), are known to bring green nesting material into their nests (Cowie & Hinsley 1988;Banbura et al 1995) no such behaviour has been described for great tits (Perrins 1979;Gosler 1993). In this study, the difference in nest mass between infested and parasite-free nests appeared to be due to more of the same nest material being brought into the nest (i.e.…”

Green Plant Material in Avian Nests

“…Such function of GM may be supported by diurnal timing of green plant deposition in the nest (Cowie and Hinsley, 1988). Blue Tit females only carry GM to the nest in the evening (Banbura et al, 1995), which may suggest that they time the most intensive emissions of volatiles for the evening and night, when many nestdwelling parasites, e.g. mites and blow fly larvae, become more active (Bennett and Whitworth, 1991;Clayton and Walther, 1997).…”