Fig 2. Family means of clutch volume in relation to the mean body mass for avian families (families follow Dickinson 2003), grey lines denoting confidence intervals (standard error) and dotted lines defining 95% confidence intervals.

Megapodes (denoted by a square) represent the only outlier with a clutch volume more than 10 standard deviations greater than the value predicted by body mass. The clutch volume of Kiwis (Apterygidae; denoted by a triangle) is not significantly greater than the value predicted by body mass.