Olfactory Communication via Microbiota: What Is Known in Birds?

Abstract

Animal bodies harbour a complex and diverse community of microorganisms and accumulating evidence has revealed that microbes can influence the hosts’ behaviour, for example by altering body odours. Microbial communities produce odorant molecules as metabolic by-products and thereby modulate the biochemical signalling profiles of their animal hosts. As the diversity and the relative abundance of microbial species are influenced by several factors including host-specific factors, environmental factors and social interactions, there are substantial individual variations in the composition of microbial communities. In turn, the variations in microbial communities would consequently affect social and communicative behaviour by influencing recognition cues of the hosts. Therefore, microbiota studies have a great potential to expand our understanding of recognition of conspecifics, group members and kin. In this review, we aim to summarize existing knowledge of the factors influencing the microbial communities and the effect of microbiota on olfactory cue production and social and communicative behaviour. We concentrate on avian taxa, yet we also include recent research performed on non-avian species when necessary.

Experimental evidence that symbiotic bacteria produce chemical cues in a songbird

“…The finding that bacteria associated with avian preen glands are capable of producing primary components of avian chemical cues and signals raises questions about the relationships between birds and their bacteria, and how these bacterially generated cues could honestly reflect host traits (Archie and Theis, 2011;Carthey et al, 2018;Maraci et al, 2018). Group members and social partners in general share microbes through social interactions and physical contact (Archie and Tung, 2015;Ross et al, 2017).…”

Some important overlooked aspects of odors in avian nesting ecology

“…A first general strategy birds might use for limiting detection of nest odors is to reduce their production, which originate from adults, eggs, nestlings, and nesting material (Hagelin 2007, Karlsson et al 2010, Amo et al 2012, Webster et al 2015, Golüke et al 2016). Each of these will in turn be influenced by avian genes, diet, habitat, and microbiomes (Maraci et al 2018). Crypsis of bird odors might be achieved by lowering metabolism while at nests (Conover 2007) and removing sources of odors such as via removal of fecal sacs (Thomson 1935, Wible 1960, Gill 1995.…”

Family matters: Skin microbiome reflects the social group and spatial proximity in wild zebra finches

“…The nest environment, as well as the social environment, influences the bacterial community on the skin of various bird species (reviewed in [20]) and can therefore be considered to be drivers for diversity in the skin microbiomes of different families.…”