Age and performance at fledging are a cause and consequence of juvenile mortality between life stages

• DOI: 10.1126/sciadv.aar1988
• Publication Date: 2018-06-20T18:15:32Z
• Authors: Thomas E. Martin; Bret Tobalske; Margaret M. Riordan; Samuel B. Case; Kenneth P. Dial
• Keywords: Fledge; Songbird; Paternal care

Should they stay or should leave? The age at which young transition between life stages, such as living in a nest versus leaving it, differs among species and the reasons why are unclear. We show that offspring of songbird leave younger have less developed wings cause poorer flight performance greater mortality after fledging. Experimentally delayed fledging verified older better provide benefits reduced juvenile mortality. Young differentially constrained can enjoy these fitness because differences opposing predation costs while nest. This tension outside influences traits creates an unrecognized conflict parents determines optimal to fledge.