[1] Newcastle Univ, Ctr Behav & Evolut, Newcastle Upon Tyne, Tyne & Wear, England
[2] Newcastle Univ, Biosci Inst, Newcastle Upon Tyne, Tyne & Wear, England
[3] Univ Calif Davis, Dept Anim Sci, Davis, CA USA
[4] Univ Bern, Ctr Proper Housing Poultry & Rabbits ZTHZ, Zollikofen, Switzerland
[5] Newcastle Univ, Sch Nat & Environm Sci, Newcastle Upon Tyne, Tyne & Wear, England
[6] SRUC, Dept Agr Hort & Engn Sci, Edinburgh, Midlothian, Scotland