Aromatic plants in nests of the blue tit Cyanistes caeruleus protect chicks from bacteria

Abstract

Several bird species add fresh fragments of plants which are rich in volatile secondary compounds to their nests. It has been suggested, although never tested, that birds use fresh plants to limit the growth of nest microorganisms. On Corsica, blue tits (Cyanistes caeruleus) incorporate fresh fragments of aromatic plants into their nests. These plants do not reduce infestation by nest ectoparasites, but have been shown to improve growth and condition of chicks at fledging. To understand the mechanisms underlying such benefits, we experimentally tested the effects of these plants on the bacteria living on blue tits. Aromatic plants significantly affected the structure of bacterial communities, in particular reducing bacterial richness on nestlings. In addition, in this population where there is a strong association between bacterial density and infestation by blood-sucking Protocalliphora blow fly larvae, these plants reduced bacterial density on the most infested chicks. Aromatic plants had no significant effect on the bacteria living on adult blue tits. This study provides the first evidence that fresh plants brought to the nests by adult birds limit bacterial richness and density on their chicks.

Differences in Culturable Microbial Communities in Bird Nestboxes According to Orientation and Influences on Offspring Quality in Great Tits (Parus major)

“…and Enterobacter spp. These genera have been previously associated with birds or their nesting 348 environments [3,40,42], and were three of the four genera of bacteria most often associated with house wren (Troglodytes aedon) nests [60]. In our study, the main Pseudomonas species were P. fluorescens, P. putida and P. veronii, which have been recorded before in nesting material of great tits (Parus major) [20].…”

Use of anthropogenic material affects bird nest arthropod community structure: influence of urbanisation, and consequences for ectoparasites and fledging success

“…Aromatic plants may offer an anti-ectoparasite or even anti-bacterial function in nests (Mennerat et al 2009a;Tomás et al 2012;Ruiz-Castellano et al 2016). Fewer native aromatic plants may be available at higher levels of urbanisation even though the overall plant diversity can be higher due to the planting of exotic plant species in gardens and other areas (McKinney 2008).…”

“…Nest composition may influence ectoparasite load by affecting larval mortality and growth through effects on nest humidity (Heeb et al 2000) or through the attraction/repellence effects of the materials themselves (Remeš and Krist 2005;Mennerat et al 2009a;Tomás et al 2012). As nest construction and host defence behaviour may differ significantly between species utilising similar nest sites in a local area, ectoparasite loads may also differ (Moreno et al 2009).…”

Causes and Consequences of Intraspecific Variation in Nesting Behaviors: Insights from Blue Tits and Great Tits

“…There is variation in the amount of aromatic plant material incorporated into the nests of blue tits, however, and that variation is determined not by the availability of aromatic plant material within territories or by the breeding experience of nest-building females but by female identity as individual females showed preferences for aromatic plant materials that were repeatable both within and across years (Mennerat et al, 2009a). Meanwhile, the inclusion of aromatic plants within nests significantly affects the structure of bacterial communities as the experimental addition of aromatic plant materials reduced the level of bacterial richness on nestling but not adult blue tits (Mennerat et al, 2009c). This appears to benefit the nestlings as the experimental addition of aromatic plants to blue tit nests resulted in faster growth of nestlings in experimental nests than in control broods where mosses, which are a benign plant species, were added to nests (Mennerat et al, 2009b).…”