Olfactory Assessment of Competitors to the Nest Site: An Experiment on a Passerine Species

Abstract

Since most avian species have been considered anosmic or microsmatic, olfaction and associated behavioural patterns have hardly been investigated. Most importantly, empirical data on avian olfaction is not equally distributed among species. Initial investigations focused on species with relatively big olfactory bulbs because they were thought to have better olfactory capabilities. Hence, in this study we tested the ability of house sparrows (Passer domesticus) to use chemical cues as parameters to estimate nest features. House sparrows are a commonly used model species, but their olfactory capabilities have not been studied so far. We offered two different odours to males and females, namely the scent of mouse urine (Mus musculus domesticus), representing a possible competitor and a threat to eggs and hatchlings, and the odour of hay, representing a familiar and innocuous odour. The experiment was performed at the sunset to simulate a first inspection to new possible roosting or nesting sites. Interestingly, males but not females preferred to spend significantly more time in front of the hay odour, than in front of the scent of mouse urine. Our results strengthen the hypothesis that oscines can not only perceive odours but also use olfaction to assess the environment and estimate nest site quality.

House sparrows’ (Passer domesticus) behaviour in a novel environment is modulated by social context and familiarity in a sex-specific manner

“…Pine trees had the same size, shape and height (1.5 m) while branches came from trees near the research institute. All aviaries were provided with food (a mixture of millet, canary seeds, wheat, sunflower seeds, protein-based mash, plus apple slices and millet sprays hanging from the branches) and water poured in a dish on the ground [ 58 , 59 ]. All the study subjects were housed together in 5 housing aviaries and all individuals not belonging to the age-class of the study subjects were removed from the 5 housing aviaries 50 days before the start of the experiment, leaving 19.2 ± 1.8 sparrows in each aviary (range: 15–25 sparrows).…”

Wild great and blue tits do not avoid chemical cues of predators when selecting cavities for roosting

“…exposed to fox scent did [ 30 ]. Moreover, male house sparrows ( Passer domesticus ) avoided the scent of a potential predator or competitor ( Mus musculus domesticus ) when inspecting nest-boxes for roosting [ 31 ]. However, in other cases, the presence of predator scent did not affect nesting preferences ( Sialia sialis [ 32 ]) or parental behaviour ( Troglodytes aedon [ 33 ]); or nesting was not avoided ( Puffinus pacificus [ 34 ]).…”

MHC‐mediated sexual selection on birdsong: Generic polymorphism, particular alleles and acoustic signals

“…Proximate mechanisms functioning in MHC‐mediated mate choice typically include odour signals in many animals, as MHC molecules can be bound to volatile chemicals that are excreted via the skin, urine or faeces thus can contribute to body odours (Carroll, Penn, & Potts, ; Milinski, Croy, Hummel, & Boehm, ; Milinski et al., ; Olsson et al., ; Penn, ). In birds, chemical signalling is still poorly recognized, but the secretion of the uropygial gland or feather microflora have recently been implicated as a potential source of scent cue for MHC signalling (Leclaire et al., ; Slade et al., ; Strandh et al., ), while olfactory perception has also been described at least in some species (Fracasso, Tuliozi, Hoi, & Griggio, ; Griggio, Fracasso, Mahr, & Hoi, ). In animals that only partially rely on olfactory cues, condition‐dependent visual or behavioural traits can signal genetic resistance, because only males with high immunocompetence (as determined by their MHC genotype) can bear the costs of elaborated sexual displays (Folstad & Karter, ; Hamilton & Zuk, ).…”

“…In birds, chemical signalling is still poorly recognized, but the secretion of the uropygial gland or feather microflora have recently been implicated as a potential source of scent cue for MHC signalling (Leclaire et al, 2014;Slade et al, 2016;Strandh et al, 2012), while olfactory perception has also been described at least in some species (Fracasso, Tuliozi, Hoi, & Griggio, 2018;Griggio, Fracasso, Mahr, & Hoi, 2016). In animals that only partially rely on olfactory cues, condition-dependent visual or behavioural traits can signal genetic resistance, because only males with high immunocompetence (as determined by their MHC genotype) can bear the costs of elaborated sexual displays (Folstad & Karter, 1992;Hamilton & Zuk, 1982).…”