## Bonferroni corrections were applied to take account of the eight

As in our previous work (Edgar et al., 2011), we found a pronounced set of behavioural and physiological changes in hens when their chicks were subjected to an air puff. Hens had an increased BAF312 rate (pretreatment period mean = 275 ± 14 bpm; treatment period mean = 337 ± 14 bpm; Wilks's lambda = 2.64, F1,11 = 30.625, P < 0.001, partial eta2 = 0.736), time spent standing alert (pretreatment period median = 19.9%, interquartile range, IQR = 82.6; treatment period median = 78.7%, IQR = 48.8; Wilks's lambda = 0.598, F1,11 = 7.392, P = 0.020, partial eta2 = 0.402) and time spent vocalizing (pretreatment period median = 1.2%, IQR = 7; treatment period median = 5.5%, IQR = 38.6; Wilks's lambda = 0.591, F1,11 = 7.622, P = 0.019, partial eta2 = 0.409) and a decreased eye temperature (pretreatment period mean = 33.8 ± 0.4 °C; treatment period mean = 32.4 ± 0.3 °C; Wilks's lambda = 0.360, F1,11 = 19.573, P = 0.001, partial eta2 = 0.640) when observing the Group 1 chicks receiving an air puff. There were no other significant behavioural or comb temperature changes.