A note on fear reaction of three different genetic strains of laying hens to a simulated hawk attack in the hen run of a free-range systemEstherZeltnerauthorHelenHirtauthorHens well adapted to free-range systems should react quickly to avoid an attack by a predator but should also be able to return to the hen run soon after to ensure good use of the outside area. Poultry Breeding and genetics2008Elsevier B.V.Journal paper