[Experimental studies on the significance of mouth markings in zebra finch nestlings].

Wild-coloured Zebra Finch nestlings with fully developed mouth markings were compared with white mutants, which lack the markings, with respect to the ability of these markings to release the feeding response of both wild-coloured and white parents. In more than 80 nestlings, the wild-coloured ones proved to have a higher survival rate, to grow faster, to be given more food, and to have piority to the first feedings in the day. Within the colour groups greater relative age was as advantageous as mouth markings were between groups.