Fledging in altricial birds: Parental manipulation or sibling competition?

Research output: Contribution to journalArticle


In altricial birds, the period of parental investment covers three distinctly separated phases: Incubation, feeding of nestlings, and feeding of fledglings in the family group. The transition between the latter two phases occurs when the brood fledges and leaves the nest. To investigate which party, parents or offspring, initiates nest leaving, different-aged broods were swopped between nestboxes in two passerine bird species, the marsh tit, Parus palustris, and the pied flycatcher, Ficedula hypoleuca. Parents did not try to manipulate nestlings into nest leaving; fledging was thus independent of the level of parental investment. Instead, fledging occurred when one of the nestlings, which had reached a certain threshold size, left the nest in order to approach the parents and obtain additional feedings at the expense of its siblings. It is suggested that the fledging time of altricial birds is determined by energetic considerations and by sibling competition. Since fledging also represents the juvenile's transition from an inactive to an active party in the parent-offspring interaction, it is also to be considered as an escalation of the parent-offspring conflict.


External organisations
  • Lund University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Behavioral Sciences Biology
Original languageEnglish
Pages (from-to)379-386
JournalAnimal Behaviour
Issue number2
Publication statusPublished - 1993 Jan 1
Publication categoryResearch