Rats and mice show changes in behaviour when they see close relatives in distress. It seems that chickens might also display signs of empathy — an ability to share another's emotional state. If farm animals empathize more widely with their fellows, farmers may need to take extra measures to limit stress to animals during handling, transportation and slaughter.

Credit: J. BURTON/NATURE PICTURE LIBRARY

Joanne Edgar at the University of Bristol, UK, and her co-workers placed individual hens and their chicks in boxes, separating hen and chicks with a clear plastic sheet, and puffed the chicks with bursts of air. In response, the mothers' behaviour and physiology changed, with greater clucking and an increased heart beat.

Proc. R. Soc. B doi:10.1098/rspb.2010.2701 (2011)