“…Similarly, parents allocate less energy to egg heating when incubation costs are experimentally relieved (Bryan & Bryant 1999;Cresswell et al 2004;Pe´rez et al 2008;Ardia et al 2009; D'Alba, Monaghan & Nager 2009). In line with this, variation in the amount of energy required for incubation has been shown to affect a variety of parental and neonatal fitness components, such as adult survival (Visser & Lessells 2001;de Heij, van den Hout & Tinbergen 2006), future fecundity (Hanssen et al 2005), chick rearing capacity (Heaney & Monaghan 1996;Reid, Monaghan & Ruxton 2000a,b;de Heij, van den Hout & Tinbergen 2006), hatching success (Moreno et al 1991;Siikama¨ki 1995;Reid, Monaghan & Ruxton 2000a,b;, fledging success (Reid, Monaghan & Ruxton 2000a,b;Ilmonen, Taarna & Hasselquist 2002), fledgling mass (Cichon 2000), nestling growth rate (Pe´rez et al 2008;Nilsson, Stjernman & Nilsson 2008) and incubation duration (Coleman & Whittall 1988;Moreno & Carlson 1989;Smith 1989;Siikama¨ki 1995;Wiebe & Martin 2000;Engstrand, Ward & Bryant 2002;Dobbs, Styrsky & Thompson 2006).…”