This file gives data for the 227 out of 240 planned ‘Supertests’ of 20min (after excluding 13 tests cancelled because two females died). This is the data for Figure1, Table 2 and Table S4. Here ‘high’ and ‘low’ always refer to traits of the high- and low-fecundity females, respectively, and ‘difference’ always refers to ‘high’ minus ‘low’. Given are the individual IDs, age in days, beak colour (‘BC’), body mass, and responsiveness. ‘Maletest’ refers to a male’s first vs. second choice test, ‘male_choosing_motivation’ is the sum of seconds the male is actively paying attention (theoretical max = 1,200 sec), ‘PrefHighFec’ is then the relative time with the high-fecundity female and ‘correct’ is 1 when ‘PrefHighFec’>0.5. Cases of missing data are explained in ‘comment’.