Abstract: Parent-offspring conflict is thought to have resulted in competitive signaling systems in some species.  Such systems have evolved because they enable parents to judge offspring need or quality and allocate resources in a manner that contributes to their overall fitness.  The color of the begging gape of nestling passerine birds is one mechanism of solicitation that may have been selected as a competitive signal.  We examined whether the begging gape of three day-old junco nestlings (Junco hyemalis) is a competitive signal of hunger by testing whether food-deprived nestlings had brighter gapes than their satiated siblings and whether parents preferentially-fed nestlings with experimentally reddened gapes.  We found that mouth color changed significantly over the 1 hour experimental period but was not affected by hunger level.  Parents in the field portion of the study did not respond to reddened nestling mouths with preferential feeding.  These results suggest that mouth color does not signal nestling hunger in the dark-eyed junco.  However, they show that mouth color varied with some component of experimental treatment, perhaps stress or body temperature.  Parents may detect and behaviorally respond to this change.  We conclude this paper with suggestions for future research.