An Easy Method to Test Odour Recognition in Songbird Hatchlings

Abstract

We describe an easy method to test odour detection and recognition in 1‐d‐old zebra finch hatchlings (Taeniopygia guttata). Day‐old chicks beg in a stereotypical posture, which can be induced by directing gentle puffs of air from a plastic wash bottle near the face. We used this method to experimentally test whether begging duration of chicks was indicative of nest odour recognition. We manipulated the olfactory environment of 12 nests throughout incubation and hatching with either an artificial odour (orange oil) or with a neutral control (tap water). We then presented these two stimulus odours to 25 day‐old chicks and measured the duration of the first begging bout exhibited for each odour. Zebra finches hatched in a nest environment enriched with orange oil scent begged significantly longer when exposed to orange oil odour, compared to control hatchlings. Our simple testing procedure can be used to efficiently quantify odour recognition and/or preference in altricial songbirds at a very early developmental stage.

Begging blue tit nestlings discriminate between the odour of familiar and unfamiliar conspecifics

“…However, it should be noted that in a previous study on zebra finches, 1-day old chicks begged longer towards a familiar, albeit artificial, odour stimulus (i.e. orange oil) compared with a non-familiar stimulus (Caspers et al 2015b).…”

“…We developed the odour discrimination test procedure by combining a begging test protocol previously applied to wild blue tits (Lucass et al 2016) and an olfactory test protocol based on individual begging responses previously applied to zebra finches in the laboratory (Caspers et al 2015b). Directly after being placed individually in the test chamber, each nestling was stimulated to beg and fed with a maximum of three defrosted fly larvae (purchased at the local pet shop and normally used as fishing bait), depending on the nestlings appetite, in order to 'equalise' the nestlings' hunger level at the start of the odour test trials (for details on the feeding protocol see Supporting Information, Data S1).…”

“…During each test, we gently opened the test chamber, removed the cloth, and once the nestling was motionless again, we started the odour discrimination test procedure (method adapted from Caspers et al 2015b). To provide an odour stimulus and induce the nestling's begging behaviour, we directed soft puffs of air from the wash bottle containing the odour sample, within 2 cm of the nestling's head.…”

“…Very recently, a study on captive zebra finches ( Taeniopygia guttata ) has demonstrated that begging duration in response to different odour stimuli can be used to investigate odour discrimination in 1‐day old nestlings (Caspers et al . ). Previously, it has also been reported that 1‐day old domestic chicks ( Gallus gallus domesticus ) differ in their behavioural responses to different artificial odour stimuli (Porter et al .…”

“…The present study aims to investigate whether olfactory cues from nest-mates have the potential to influence the begging behaviour of competing nestlings by testing the begging response of blue tit nestlings to an olfactory stimulus originating from familiar vs. unfamiliar conspecifics. Very recently, a study on captive zebra finches (Taeniopygia guttata) has demonstrated that begging duration in response to different odour stimuli can be used to investigate odour discrimination in 1-day old nestlings (Caspers et al 2015b). Previously, it has also been reported that 1-day old domestic chicks (Gallus gallus domesticus) differ in their behavioural responses to different artificial odour stimuli (Porter et al 1999).…”