Schematic representation of the olfactometric device used.

<p>A focal female was introduced into the central chamber and exposed to scent-carrying air flowing in (solid arrows) from the choice chambers. Odour donor nestlings were hidden from the focal female's view behind a dense plastic mesh (fine cross hatching). A choice was scored when the female entered one of the choice chambers after opening the doors (dotted arrows).</p

Number of females choosing their own or a foreign nestling scent.

<p>Number of female spotless starlings that chose the side of the chamber containing the scent of their own nestling or the scent of a foreign nestling (p = 1.00), when a) nestlings were 5–6 day old and have the uropygial gland closed or b) when nestlings were 12–14 day old and have the uropygial gland open.</p